Which gas in the atmosphere can be turned into fertilizer by some microbes?

Fertilizer use responsible for increase in nitrous oxide in atmosphere | Berkeley News Fertilizer use responsible for increase in nitrous oxide in atmosphere By Robert Sanders , Media relations | April 2, 2012 Robert Sanders University of California, Berkeley, chemists have found a smoking gun proving that increased fertilizer use over the past 50 years is responsible for a dramatic rise in atmospheric nitrous oxide, which is a major greenhouse gas contributing to global climate change. The Cape Grim Baseline Air Pollution Station in Tasmania, where air samples have been collected since 1978. These samples show a long-term trend in isotopic composition that confirms that nitrogen-based fertilizer is largely responsible for the 20 percent increase in atmospheric nitrous oxide since the Industrial Revolution. Photo courtesy of CSIRO. Climate scientists have assumed that the cause of the increased nitrous oxide was nitrogen-based fertilizer, which stimulates microbes in the soil to convert nitrogen to nitrous oxide at a faster rate than normal. The new study, reported in the April issue of the journal Nature Geoscience, uses nitrogen isotope data to identify the unmistakable fingerprint of fertilizer use in archived air samples from Antarctica and Tasmania. “Our study is the first to show empirically from the data at hand alone that the nitrogen isotope ratio in the atmosphere and how it has changed over time is a fingerprint of fertilizer use,” said study leader Kristie Boering, a UC Berkeley professor of chemistry and of earth and planetary science. “We are not vilifying fertilizer. We can’t just stop using fertilizer,” she added. “But we hope this study will contribute to changes in fertilizer use and agricultural practices that will help to mitigate the release of nitrous oxide into the atmosphere.” Since the year 1750, nitrous oxide levels have risen 20 percent – from below 270 parts per billion (ppb) to more than 320 ppb. After carbon dioxide and methane, nitrous oxide (N2O) is the most potent greenhouse gas, trapping heat and contributing to global warming. It also destroys stratospheric ozone, which protects the planet from harmful ultraviolet rays. Not surprisingly, a steep ramp-up in atmospheric nitrous oxide coincided with the green revolution that increased dramatically in the 1960s, when inexpensive, synthetic fertilizer and other developments boosted food production worldwide, feeding a burgeoning global population. Tracking the origin of nitrous oxide in the atmosphere, however, is difficult because a molecule from a fertilized field looks identical to one from a natural forest or the ocean if you only measure total concentration. But a quirk of microbial metabolism affects the isotope ratio of the nitrogen the N2O microbes give off, producing a telltale fingerprint that can be detected with sensitive techniques. Archived air from Cape Grim Boering and her colleagues, including former UC Berkeley graduate students Sunyoung Park and Phillip Croteau, obtained air samples from Antarctic ice, called firn air, dating from 1940 to 2005, and from an atmospheric monitoring station at Cape Grim, Tasmania, which has archived air back to 1978. Law Dome, Antarctica. Air trapped in the consolidated snow from this region provides historical air samples going back to 1940. Analysis of N2O levels in the Cape Grim air samples revealed a seasonal cycle, which has been known before. But isotopic measurements by a very sensitive isotope ratio mass spectrometer also displayed a seasonal cycle, which had not been observed before. At Cape Grim, the isotopes show that the seasonal cycle is due both to the circulation of air returning from the stratosphere, where N2O is destroyed after an average lifetime of 120 years, and to seasonal changes in the ocean, most likely upwelling that releases more N2O at some times of year than at others. “The fact that the isotopic composition of N2O shows a coherent signal in space and time is exciting, because now you have a way to differentiate agricultural N2O from natural ocean N2O from Amazon f


Which layer of the Earth is believed to be formed of molten iron and nickel?

Layers of the Earth Layers of the Earth   The earth is made up of layers (crust, mantle, outer core, and inner core).   Each one has a unique make-up to it. Crust  This is the outer layer of the Earth about 10 miles or so thick. Mostly made up of rock and loose material.  The crust found underneath continents is 3 times thicker than the crust underneath the oceans. Mantle The next layer beneath the crust is called the mantle.  It extends to a depth of approximately 1,800 miles and is made of a thick solid rocky substance that represents about 85% of the total weight and mass of the Earth. The first 50 miles of the mantle are believed to consist of very hard rigid rock. The next 150 miles or so is believed to be super-heated solid rock. Below that for the next several hundred miles, the Earth mantle is once again made up of very solid and sturdy rock materials. Outer Core Traveling deeper within the Earth, we next would encounter the Earth’s outer core, which extends to a depth of around 3000 miles beneath the surface. It is believed that this outer core is made up of super-heated liquid molten lava. This lava is believed to be mostly iron, and nickel. Inner Core Finally, we would reach the Earth’s inner core. The inner core extends another 900 miles inward towards the center of the Earth. It is believed that this inner core is a solid ball of mostly iron, and nickel. The mantle is made of much denser, thicker material, because of this the plates "float" on it like oil floats on water.  Many geologists believe that the mantle "flows" because of convection currents. Convection Currents These currents are caused by the very hot material rising, cooling, and sinking over and over again.  The next time you heat anything like soup or pudding in a pan you can watch the convection currents move in the liquid. When the convection currents flow in the mantle they also move the crust. The crust gets a free ride with these currents. A conveyor belt in a factory moves boxes like the convection currents in the mantle moves the plates of the Earth. Magma The first question this raises is: what exactly is this "material from the inside"? On our planet, it's magma, fluid molten rock. This material is partially liquid, partially solid and partially gaseous. Radiation


What is the collective noun for rhinoceri?

What Is a Group of Snakes Called? What Is a Group of Snakes Called? Tweet A group of snakes is generally called a bed, den, pit or nest, but a group of rattlesnakes is referred to as a rhumba or rumba. It's not entirely clear why it is called a rhumba, but the word comes from a Cuban Spanish term, rumba, which originally meant "party" or "carousel." Terms such as "bed" or "rhumba" are known as collective nouns when they refer to groups of animals. More collective nouns for animal groups: A group of monkeys is often called a tribe or troop, but it can also be called a shrewdness of monkeys. Groups of baboons specifically can be called a flange or congress of baboons, and groups of chimpanzees can be called a harem of chimpanzees. Perhaps appropriately, a group of cockroaches is called an intrusion of cockroaches. A group of rats is often called a pack, but it also can be called a mischief. Crows also have particularly negative collective nouns, including an unkindness of crows, as well as a congress, a conspiracy, a parliament and a murder of crows. Doves have a more positive group of names, including a cote of doves and a piteousness of doves. A group of ants can be called a bike of ants, and a group of bees can be called a grist of bees. Groups of alligators or crocodiles are called congregations, and groups of Komodo dragons are called banks. Both a group of hippopotami and a group of rhinoceri can be called a crash. A group of hippopotami also can be called a bloat. Follow wiseGEEK:


What type of rock is formed by the rapid cooling of molten lava?

How is obsidian formed? | Reference.com How is obsidian formed? A: Quick Answer Obsidian is formed by rapidly cooling molten rock or lava. Obsidian is also called volcanic glass, and it is considered a mineraloid. Full Answer Examples of the rapid cooling that forms obsidian are lava oozing into a body of water, or lava splashing against something and bouncing into the air. Most obsidian is black; however, it can also be found in other colors. Scientists believe the colors come from other elements mixing in with the molten rock just before the rapid cooling occurs. Most obsidian found is from volcanic eruptions that occurred within the past few million years. That is because older obsidian has most likely shattered into dust over time, as stated by geology.com.


What name is given to the rock formations used as a source of water?

USGS Water Science Glossary of Terms A | B | C | D | E | F | G | H | I | K | L | M | N | O | P | R | S | T | U | V | W | X | Y A acequia--acequias are gravity-driven waterways, similar in concept to a flume. Most are simple ditches with dirt banks, but they can be lined with concrete. They were important forms of irrigation in the development of agriculture in the American Southwest. The proliferation of cotton, pecans and green chile as major agricultural staples owe their progress to the acequia system. acid--a substance that has a pH of less than 7, which is neutral. Specifically, an acid has more free hydrogen ions (H+) than hydroxyl ions (OH-). acre-foot (acre-ft)--the volume of water required to cover 1 acre of land (43,560 square feet) to a depth of 1 foot. Equal to 325,851 gallons or 1,233 cubic meters. alkaline--sometimes water or soils contain an amount of alkali (strongly basic) substances sufficient to raise the pH value above 7.0 and be harmful to the growth of crops. alkalinity--the capacity of water for neutralizing an acid solution. alluvium--deposits of clay, silt, sand, gravel, or other particulate material that has been deposited by a stream or other body of running water in a streambed, on a flood plain, on a delta, or at the base of a mountain. appropriation doctrine--the system for allocating water to private individuals used in most Western states. The doctrine of Prior Appropriation was in common use throughout the arid west as early settlers and miners began to develop the land. The prior appropriation doctrine is based on the concept of "First in Time, First in Right." The first person to take a quantity of water and put it to Beneficial Use has a higher priority of right than a subsequent user. Under drought conditions, higher priority users are satisfied before junior users receive water. Appropriative rights can be lost through nonuse; they can also be sold or transferred apart from the land. Contrasts with Riparian Water Rights. aquaculture--farming of plants and animals that live in water, such as fish, shellfish, and algae. aqueduct--a pipe, conduit, or channel designed to transport water from a remote source, usually by gravity. aquifer--a geologic formation(s) that is water bearing. A geological formation or structure that stores and/or transmits water, such as to wells and springs. Use of the term is usually restricted to those water-bearing formations capable of yielding water in sufficient quantity to constitute a usable supply for people's uses. aquifer (confined)--soil or rock below the land surface that is saturated with water. There are layers of impermeable material both above and below it and it is under pressure so that when the aquifer is penetrated by a well, the water will rise above the top of the aquifer. aquifer (unconfined)--an aquifer whose upper water surface (water table) is at atmospheric pressure, and thus is able to rise and fall. artesian water--groundwater that is under pressure when tapped by a well and is able to rise above the level at which it is first encountered. It may or may not flow out at ground level. The pressure in such an aquifer commonly is called artesian pressure, and the formation containing artesian water is an artesian aquifer or confined aquifer. See flowing well artificial recharge--an process where water is put back into groundwater storage from surface-water supplies such as irrigation, or induced infiltration from streams or wells. B base flow--sustained flow of a stream in the absence of direct runoff. It includes natural and human-induced streamflows. Natural base flow is sustained largely by groundwater discharges. base--a substance that has a pH of more than 7, which is neutral. A base has less free hydrogen ions (H+) than hydroxyl ions (OH-). bedrock--the solid rock beneath the soil and superficial rock. A general term for solid rock that lies beneath soil, loose sediments, or other unconsolidated material. C capillary action--the means by which liquid moves through the porous spaces in a solid, such as soil, plant roots, and the cap


How long does it take for the Earth to spin once on its axis?

BBC - Schools Science Clips - Earth, sun and moon Offline lesson plan Offline lesson plan Objectives Understand that it is the Earth that moves, not the Sun, and the Earth spins on its axis once every 24 hours Know that it is daytime in the part of the Earth facing the Sun and night-time in the part of the Earth away from the Sun     England: Key Stage 2, Science, Sc4 4c Wales: Key Stage 2, Physical processes 4.4 Northern Ireland: Key Stage 3, Physical processes, Earth in space, b Scotland: 5-14 Guidelines, Science, Earth in space, Level B     Copies of the Earth, Sun and Moon worksheet printed from the Science Clips website Globe, light source (e.g. overhead projector light)     Teaching activities Introduction Ask a child to act as the Sun. Explain that the Sun is at the centre of the Solar System. Ask another child to act as the Earth and show how the Earth orbits around the Sun. Then ask the 'the Earth' to spin as it orbits the Sun. Does anyone know how long it takes for the Earth to spin once on its own axis? Activitives Set up the globe and the light so they are level and the light is shining on the globe. Explain to the children that the light represents the Sun, and the globe represents the Earth. How much of the Earth is in light and how much is in shadow? In which half would it be night-time and in which half would it be daytime? Locate the UK on the globe. Turn the globe so the UK is directly opposite the light, in shadow. Is it daytime or night-time in the UK? Explain that it is precisely midnight. Rotate the globe anticlockwise and stop where the change from darkness to light occurs. What would we be experiencing in the UK now? What time would it be? Continue to rotate slowly. Stop when the UK faces the light beam directly. What time would it be now in the UK (midday)? Slowly continue to rotate. Stop where the change from light to darkness occurs. What we would be experiencing in the UK now? What time would it be? Continue to rotate slowly until the UK is facing directly away from the light again. What time is it now? How long does it take for the Earth to complete one spin? Ensure children understand that one complete turn takes 24 hours (one day). Hand out copies of the worksheet. Let children complete it independently, shading in each diagram where it is night on Earth. Plenary Review the worksheet. Discuss how it doesn't appear to us on Earth that the Earth is moving, but it appears that the Sun moves and it appears to rise and set in the sky.     Extension Fasten a matchstick to the UK on the globe with a piece of blu-tack. Ask children to make observations of the shadow as they rotate the Earth through a day.     Suggested homework Ask children to calculate, using their age, the answers to the following questions. How many times have they rotated with the Earth?


What is a very hard, naturally-occurring mineral, of which ruby and sapphire are gem quality varieties?

Ruby and Sapphire: Gems of the Mineral Corundum Home » Gemstones » Ruby and Sapphire Ruby and Sapphire Ruby and sapphire have the same chemical composition and crystal structure - they are both varieties of the mineral corundum Rubies: The most desired variety of corundum is the ruby. The red color is produced by trace amounts of chromium in the mineral. These two beautiful rubies were mined in Madagascar. The one on the left is a 7 x 5 millimeter octagon that weighs about 1.32 carats. The one on the right is an 8 x 6 millimeter oval that weighs about 1.34 carats. Although Asia has been the traditional source of gem corundum for over one thousand years, Africa is poised to become a new primary source. Ruby, Sapphire, and Fancy Sapphire Most people don't realize that ruby and sapphire are both gems of the mineral corundum . Both of these gems have the same chemical composition and the same mineral structure. Trace amounts of impurities determine if a gem corundum will be a brilliant red ruby or a beautiful blue sapphire. It is surprising that "impurities" can produce such wonderful results! Red and blue are just two of the many colors found in gem corundums. Trace amounts of other elements can produce brilliant yellow, orange, green, and purple gems. Red corundums are known as "rubies," blue corundums are known as "sapphires," and corundums of any other color are known as " fancy sapphires ." Corundum produces gems in a spectrum of colors. Related:   Corundum: Mineral Summary What Makes a Ruby? Some gem-quality corundum contains trace amounts of chromium. A very small amount of chromium gives corundum a pink color. Larger amounts of chromium increase the color saturation of the stone and produce a gem with a deeper red color.  To be considered a "ruby," a corundum should have a color between orangey red and a slightly purplish red. The most desirable color is a pure vibrant red. Very few specimens of corundum have a natural color within the range required for a ruby. Very few also have the clarity required to produce a nice faceted stone. Long ago, people who prepared gem materials for cutting discovered that heating rubies under controlled conditions can intensify their color. Heating can also cause inclusions to become less visible and improve the clarity of a gem. Most rubies in the market today have been heated to improve their color and clarity. Many of them have had other treatments to improve their appearance. These treatments are normal and expected in the gem trade, but a seller should disclose them to a buyer in advance of a sale. Montana sapphire: The most widely known sapphire locality in North America is Yogo Gulch, Montana, famous for producing deep blue sapphires of excellent quality. Creative Commons photo of a gem from Barnes Jewelry, Helena, Montana, by Montanabw. Corundum as ruby, sapphire, and fancy sapphire: Gem-quality corundum is a highly prized and valuable material. When it is bright red in color, it is called "ruby." When it is deep blue, it is called "sapphire." Gem-quality corundum of any other color is called "fancy sapphire." All of the stones in this photo were mined in Africa. What Makes a Sapphire? Trace amounts of iron and titanium can develop a blue color in corundum. Blue corundums are known as "sapphires." The name "sapphire" is used for corundums that range from light blue to dark blue in color. The blue can range from a violetish blue to a greenish blue. Stones in the middle of this range, with a rich blue color, are the most desirable. Gem-quality corundum occurs in a wide range of other colors, including pink, purple, orange, yellow, and green. These stones are known as "fancy sapphires." It is surprising that a single mineral can produce gemstones of so many different colors. When the color of a sapphire is any color other than blue, the color should be used as a preceding adjective to describe the stone. For example, pink sapphire, yellow sapphire, or green sapphire. Used alone, the word "sapphire" refers only to blue corundum. The color and clarity of blue


Corundum is a mineral oxide of which metal?

oxide mineral | Britannica.com Oxide mineral maghemite Oxide mineral, any naturally occurring inorganic compound with a structure based on close-packed oxygen atoms in which smaller, positively charged metal or other ions occur in interstices. Oxides are distinguished from other oxygen-bearing compounds such as the silicates, borates, and carbonates, which have a readily definable group containing oxygen atoms covalently bonded to an atom of another element. Oxide minerals brown to indigo blue and black; also variable adamantine to metallic adamantine white to pale green, gray, or blue waxy to vitreous reddish or yellowish brown to brownish black adamantine to metallic adamantine, usually splendent 6–7 iron black to brownish black; often with iridescent tarnish 6–6½ 5.2 (columbite) to 8.0 (tantalite) corundum red (ruby); blue (sapphire); also variable adamantine to vitreous white, grayish white, colourless; variable brilliant vitreous brilliant submetallic to greasy or vitreous 5½–6½ white; grayish, greenish, reddish white vitreous blackish brown (crystals); yellowish or reddish brown adamantine-metallic steel gray; dull to bright red metallic or submetallic to dull 5–6 ruby red to reddish brown submetallic dark steel gray to iron black submetallic colourless to grayish; also green, yellow, or black vitreous perovskite (often containing rare earths) black; grayish or brownish black; reddish brown to yellow adamantine to metallic iron black to dark steel gray submetallic to dull brown to black (pyro); pale yellow to brown (micro) vitreous or resinous light steel gray to iron black metallic reddish brown to red; variable metallic adamantine steel or iron gray to black metallic dark gray to brownish black and bluish hornlike to submetallic steel to velvet black; grayish, greenish submetallic to greasy or dull 5–6 6.5–8.5 (massive); 8.0–10.0 (crystals) name refractive indices or polished section data crystal system disseminated or in pisolitic aggregates one very good cleavage only as crystals, usually tabular subconchoidal to uneven fracture tabular crystals; platy aggregates; fibrous or foliated massive one perfect cleavage repeatedly twinned crystals; crusts and concretions one imperfect cleavage tabular or prismatic, commonly twinned, crystals one distinct cleavage prismatic crystals, often in large groups; massive one distinct cleavage pyramidal or barrel-shaped crystals; large blocks; rounded grains no cleavage; uneven to conchoidal fracture omega = 1.767–1.772 octahedral, cubic, or capillary crystals; granular or earthy massive conchoidal to uneven fracture bluish white; anomalously anisotropic and plechroic isometric rosy brown-white; strongly anisotropic; distinctly pleochroic hexagonal thin, platy crystals; scaly massive; disseminated one perfect cleavage, one less so alpha = 1.682–1.706 tabular crystals; crusts and coatings; compact earthy one perfect cleavage one perfect cleavage, one less so alpha = 2.260–2.275 tabular crystals; rosettes; columnar or fibrous massive; earthy massive; reniform masses no cleavage anisotropic; weakly pleochroic; often shows lamellar twinning hexagonal thick, tabular crystals; compact massive; grains no cleavage; conchoidal fracture n = about 2.7 grayish white; anisotropic hexagonal flattened scales; isolated rounded crystals; massive one perfect cleavage, one less so alpha = 1.94 gray-white; strongly anisotropic and pleochroic orthorhombic crusts; alteration product on massicot one cleavage prismatic crystals, often in bundles; fibrous massive one very perfect cleavage, two less so alpha = 2.25 brownish gray-white; anisotropic; weakly pleochroic monoclinic irregular, rounded grains; octahedral crystals one perfect cleavage perovskite (often containing rare earths) cubic crystals massive; crusts; stalactites; earthy masses orthorhombic columnar or fibrous massive; coatings and concretions one perfect cleavage cream-white; distinctly anisotropic; very weakly pleochroic tetragonal slender to capillary prismatic crystals; granular massive; as inclusions, often oriented one distinct clea


What is the name of the force which keeps the planets in orbit around the sun?

How do the planets stay in orbit around the sun? | Cool Cosmos   How do the planets stay in orbit around the sun? The Solar System was formed from a rotating cloud of gas and dust which spun around a newly forming star, our Sun, at its center. The planets all formed from this spinning disk-shaped cloud, and continued this rotating course around the Sun after they were formed. The gravity of the Sun keeps the planets in their orbits. They stay in their orbits because there is no other force in the Solar System which can stop them. Continue the conversation on


Which planet is named after the Roman god of war?

Mars is Named After... - Universe Today   Universe Today by Jerry Coffey Mars is named after the Roman god of war. Many believe that ancient peoples associated Mars with bloodshed and war because of its red color. The Romans were not the only society to associate the planet with bloodshed. The ancient Babylonians called it Nergal, after their god of fire, war, and destruction. In keeping with the planet’s association with the god Mars, its symbol is a circle with an arrow pointing outwards from its right corner. This is meant to represent Mar’s shield and spear. That information is not nearly enough to satisfy anyone’s interest in the Red Planet, so here are a few interesting facts about Mars and its environs. The largest mountain in the Solar System is on Mars. Olympus Mons is 27 km tall. It is a shield volcano that was able to erupt for million of years because Mars does not have tectonic plate movement. This allowed the same volcanic hotspot to erupt undisturbed until the giant mountain was formed. The chemical symbol for iron is the same as the astronomical symbol for Mars. This is fitting, since the planet gets its reddish appearance from the iron oxide in the dust on its surface. A year on Mars lasts 686.98 Earth days or 1.88 Earth years. There are four seasons throughout the year like here on Earth, but each season is longer than a typical Earth season. Mars is full of water. Not liquid water like we see here on Earth, but water ice under the surface and at the bottom of craters. There is even evidence that there may be ice inside of caves on the Martian surface. These deposits are safe from the solar radiation that bombards the surface, so they are able to stay in place. Mars does not have a magnetic field at this time, but spacecraft have detected residual magnetism in rocks on the surface. That would suggest an active magnetic field millions, if not billions, of years ago. Scientist believe that the core of Mars has become too solid to rotate and is no longer capable of generating a dynamo effect. A dynamo effect is essential in producing a magnetic field. These are just a few of the interesting facts beyond who Mars is named after. Pay special attention to information generated by the Mars Express spacecraft. It has turned up a great deal of interesting data on, and under, the Martian surface. In case you’re wondering, here’s how Jupiter got its name . Here’s some historical information on Mars, the god of war, and more on Ares , the Greek version of Mars. Finally, if you’d like to learn more about Mars in general, we have done several podcast episodes about the Red Planet at Astronomy Cast. Episode 52: Mars , and Episode 91: The Search for Water on Mars . Sources:


Solar System Planets: Order of the 8 (or 9) Planets Solar System Planets: Order of the 8 (or 9) Planets By Robert Roy Britt | January 22, 2016 12:35pm ET MORE The planets of the solar system as depicted by a NASA computer illustration. Orbits and sizes are not shown to scale. Credit: NASA Ever since the discovery of Pluto in 1930, kids grew up learning about the nine planets of our solar system. That all changed starting in the late 1990s, when astronomers began to argue about whether Pluto was a planet. In a highly controversial decision , the International Astronomical Union ultimately decided in 2006 to call Pluto a “dwarf planet,” reducing the list of “real planets” in our solar system to eight.  However, astronomers are now hunting for another planet in our solar system, a true ninth planet , after evidence of its existence was unveiled on Jan. 20, 2016. The so-called "Planet Nine," as scientists are calling it, is about 10 times the mass of Earth and 5,000 times the mass of Pluto. [ Solar System Pictures: A Photo Tour ] If you insist on including Pluto , then that world would come after Neptune on the list; Pluto is truly way out there, and on a wildly tilted, elliptical orbit (two of the several reasons it got demoted). Interestingly, Pluto used to be the eighth planet, actually. More on that below. Terrestrial planets The inner four worlds are called “ terrestrial planets ,” because, like Earth, their surfaces are all rocky. Pluto, too, has a solid surface (and a very frozen one) but has never been grouped with the four terrestrials. Jovian planets The four large outer worlds — Jupiter, Saturn, Uranus, and Neptune — are known as the “Jovian planets” (meaning “Jupiter-like”) because they are all huge compared to the terrestrial planets, and because they are gaseous in nature rather than having rocky surfaces (though some or all of them may have solid cores, astronomers say). According to NASA , "two of the outer planets beyond the orbit of Mars — Jupiter and Saturn — are known as gas giants; the more distant Uranus and Neptune are called ice giants." This is because, while the first two are dominated by gas, while the last two have more ice. All four contain mostly hydrogen and helium. Dwarf planets The  IAU definition of a full-fledged planet goes like this: A body that circles the sun without being some other object's satellite, is large enough to be rounded by its own gravity (but not so big that it begins to undergo nuclear fusion, like a star) and has "cleared its neighborhood" of most other orbiting bodies. Yeah, that’s a mouthful. The problem for Pluto, besides its small size and offbeat orbit, is that it shares its space with lots of other objects in the Kuiper Belt , beyond Neptune. Still, the demotion of Pluto remains controversial . The IAU planet definition puts other small, round worlds in the dwarf planet category, including the Kuiper Belt objects Eris , Haumea , and Makemake . Also now a dwarf planet is Ceres , a round object in the Asteroid Belt between Mars and Jupiter. Ceres was actually considered a planet when discovered in 1801 and then later deemed to be an asteroid. Some astronomers like to consider Ceres as a 10th planet (not to be confused with Nibiru or Planet X ), but that line of thinking opens up the possibility of there being 13 planets, with more bound to be discovered. The planets Below is a brief overview of the eight primary planets in our solar system , in order from the inner solar system outward: Mercury The closest planet to the sun, Mercury is only a bit larger than Earth's moon. Its day side is scorched by the sun and can reach 840 degrees Fahrenheit (450 Celsius), but on the night side, temperatures drop to hundreds of degrees below freezing. Mercury has virtually no atmosphere to absorb meteor impacts, so its surface is pockmarked with craters, just like the moon. Over its four-year mission, NASA's MESSENGER spacecraft has revealed views of the planet that have challenged astronomers' expectations. Discovery: Known to the ancients and visible to the naked eye Named for: M


Which two planets take less time than Earth to orbit the sun?

Planets | Scholastic Grades 3–5, 6–8, 9–12 The following questions were answered by astronomer Dr. Cathy Imhoff of the Space Telescope Science Institute. Do all the planets have seasons? What causes seasons? Earth is tilted with respect to its orbit around the sun. So when our North Pole is tilted toward the sun, we get summer in the Northern Hemisphere (winter in the south). When the South Pole is tilted toward the sun, we get winter. So if a planet is tilted with respect to its orbit around the sun, it should have seasons. Here are the numbers that I was able to find this morning (as of September 1994) Venus — 23 degrees tilt, Earth — 23.5, Mars — 24, Jupiter — 3, Saturn — 27, Uranus — 98, Neptune — 29. But you can see that most of the planets have tilts like Earth, so they must have seasons. As I noted above, we definitely see seasons on Mars. In winter its ice caps grow, in summer they shrink. Jupiter has very little tilt, so it doesn't experience noticeable seasons. But Neptune is turned all the way over on its side! It must have very strange seasons! How did the planets get their names? Five of the planets were known to people thousands of years ago. They are bright enough to be seen with the naked eye and they move with respect to the stars. The name planet comes from the Greek word for "wanderer." I'm sure that people in different lands had various names for them, but the names we use come from the ancient Greeks and Romans. They named the planets for some of their gods. Mercury was the Roman god of commerce and cunning, and also messenger to the gods. Venus was the goddess of love. Mars was the god of war. Jupiter was the chief god. Saturn was the god of agriculture. When the next planet was found by Sir William Herschel in 1781, there was quite a debate about what to name it. Finally everyone decided to stay with the Roman names from mythology. So the new planet was finally named Uranus, for the father of the Titans. The next planet was named Neptune, for the god of the seas. And Pluto was named for the god of the underworld. Most of the moons and some asteroids are also named from Roman mythology. What was the first planet discovered? Who discovered it? What kind of equipment did they use? Five planets have been known since ancient times — Mercury, Venus, Mars, Jupiter, and Saturn. The first new planet discovered was Uranus. It was discovered by the English astronomer Sir William Herschel in 1781. Herschel was one of the first modern astronomers. His patron was King George III of England (the same King George from the time of the American Revolution!). Herschel wanted to name the planet after King George, but nobody else liked that so they gave it the name Uranus. Herschel and his sister Charlotte (who was an astronomer in her own right) used several reflecting telescopes, some of the first based on a design invented by Sir Isaac Newton. The largest was over 40 feet long and had a mirror 48 inches across. It was held up with a framework of wood, and they had to have helpers move it around using ropes and pulleys. It was the largest telescope in the world until over 100 years later. Which planet was formed first and how was it formed? We think that the planets all formed pretty much at the same time. However the sun probably formed first. The leftover gas and dust remained in a disk around the sun. In this disk, stuff began to clump and form "planetesimals" (pronounced pla-ne-TE-si-mals). These are small rocky bodies, something like asteroids. They crashed into each other and eventually formed the inner planets. At the same time, planetesimals formed the cores of the outer planets Jupiter and Saturn. Because of their strong gravity, they swept up a lot of gas. Uranus and Neptune did this too, but there was less gas around because Jupiter and Saturn got it first. The asteroid belt may be left-over planetesimals that never formed a planet because Jupiter's strong gravity nearby kept it from forming. Are there any living things on any of the planets? So far we know of only one planet with life — Earth! In 1976, we


Which planet has a day which lasts eight months?

How Long Is A Day On The Other Planets Of The Solar System? - Universe Today   Universe Today How Long Is A Day On The Other Planets Of The Solar System? Article Updated: 24 Jan , 2016 by Matt Williams Here on Earth, we tend to take time for granted, never suspected that the increments with which we measure it are actually quite relative. The ways in which we measure our days and years, for example, are actually the result of our planet’s distance from the Sun, the time it takes to orbit, and the time it takes to rotate on its axis. The same is true for the other planets in our Solar System. While we Earthlings count on a day being about 24 hours from sunup to sunup, the length of a single day on another planet is quite different. In some cases, they are very short, while in others, they can last longer than years – sometimes considerably! Let’s go over how time works on other planets and see just how long their days can be, shall we? A Day On Mercury: Mercury is the closest planet to our Sun, ranging from 46,001,200 km at perihelion (closest to the Sun) to 69,816,900 km at aphelion (farthest). Since it takes 58.646 Earth days for Mercury to rotate once on its axis – aka. its sidereal rotation period – this means that it takes just over 58 Earth days for Mercury to experience a single day. However, this is not to say that Mercury experiences two sunrises in just over 58 days. Due to its proximity to the Sun and rapid speed with which it circles it, it takes the equivalent of 175.97 Earth days for the Sun to reappear in the same place in the sky. Hence, while the planet rotates once every 58 Earth days, it is roughly 176 days from one sunrise to the next on Mercury. Images of Mercury’s northern polar region, provided by MESSENGER. Credit: NASA/JPL What’s more, it only takes Mercury 87.969 Earth days to complete a single orbit of the Sun (aka. its orbital period). This means a year on Mercury is the equivalent of about 88 Earth days, which in turn means that a single Mercurian (or Hermian) year lasts just half as long as a Mercurian day. What’s more, Mercury’s northern polar regions are constantly in the shade. This is due to it’s axis being tilted at a mere 0.034° (compared to Earth’s 23.4°), which means that it does not experience extreme seasonal variations where days and nights can last for months depending on the season. On the poles of Mercury, it is always dark and shady. So you could say the poles are in a constant state of twilight. A Day On Venus: Also known as “Earth’s Twin”, Venus is the second closest planet to our Sun – ranging from 107,477,000 km at perihelion to 108,939,000 km at aphelion. Unfortunately, Venus is also the slowest moving planet, a fact which is made evident by looking at its poles. Whereas every other planet in the Solar System has experienced flattening at their poles due to the speed of their spin, Venus has experienced no such flattening. Venus has a rotational velocity of just 6.5 km/h (4.0 mph) – compared to Earth’s rational velocity of 1,670 km/h (1,040 mph) – which leads to a sidereal rotation period of 243.025 days. Technically, it is -243.025 days, since Venus’ rotation is retrograde. This means that Venus. rotates in the direction opposite to its orbital path around the Sun. The planet Venus, as imagined by the Magellan 10 mission. Credit: NASA/JPL So if you were above Venus’ north pole and watched it circle around the Sun, you would see it is moving clockwise, whereas its rotation is counter-clockwise. Nevertheless, this still means that Venus takes over 243 Earth days to rotate once on its axis, which means that many, many days pass between one sunrise and the next. This may seem odd, until you consider that a single Venusian (or Cytherean) year works out to 224.701 Earth days. Yes, Venus takes a little more than 224 days to complete a single orbital period, but over 243 days to experience a single day and night cycle. So basically, a single Venusian day is longer than a Venusian year! Good thing Venus has other things in common With Earth, because it is sure isn’t its diurnal cy


What is the term for a natural satellite?

What does Natural satellite mean? This page provides all possible meanings and translations of the word Natural satellite Freebase(4.60 / 5 votes)Rate this definition: Natural satellite A natural satellite, or moon, is a celestial body that orbits another body, e.g. a planet, which is called its primary. There are 173 known natural satellites orbiting planets in the Solar System, as well as at least eight orbiting IAU-listed dwarf planets. As of January 2012, over 200 minor-planet moons have been discovered. There are 76 known objects in the asteroid belt with satellites, four Jupiter trojans, 39 near-Earth objects, and 14 Mars-crossers. There are also 84 known natural satellites of trans-Neptunian objects. Some 150 additional small bodies have been observed within rings of Saturn, but only a few were tracked long enough to establish orbits. Planets around other stars are likely to have satellites as well, though numerous candidates have been detected to date, none have yet been confirmed. Of the inner planets, Mercury and Venus have no natural satellites; Earth has one large natural satellite, known as the Moon; and Mars has two tiny natural satellites, Phobos and Deimos. The large gas giants have extensive systems of natural satellites, including half a dozen comparable in size to Earth's Moon: the four Galilean moons, Saturn's Titan, and Neptune's Triton. Saturn has an additional six mid-sized natural satellites massive enough to have achieved hydrostatic equilibrium, and Uranus has five. It has been suggested that some satellites may potentially harbour life, though there is currently no direct evidence of life. Numerology The numerical value of Natural satellite in Chaldean Numerology is: 6 Pythagorean Numerology


First man in space - Apr 12, 1961 - HISTORY.com First man in space Publisher A+E Networks On April 12, 1961, aboard the spacecraft Vostok 1, Soviet cosmonaut Yuri Alekseyevich Gagarin becomes the first human being to travel into space. During the flight, the 27-year-old test pilot and industrial technician also became the first man to orbit the planet, a feat accomplished by his space capsule in 89 minutes. Vostok 1 orbited Earth at a maximum altitude of 187 miles and was guided entirely by an automatic control system. The only statement attributed to Gagarin during his one hour and 48 minutes in space was, “Flight is proceeding normally; I am well.” After his historic feat was announced, the attractive and unassuming Gagarin became an instant worldwide celebrity. He was awarded the Order of Lenin and given the title of Hero of the Soviet Union. Monuments were raised to him across the Soviet Union and streets renamed in his honor. The triumph of the Soviet space program in putting the first man into space was a great blow to the United States, which had scheduled its first space flight for May 1961. Moreover, Gagarin had orbited Earth, a feat that eluded the U.S. space program until February 1962, when astronaut John Glenn made three orbits in Friendship 7. By that time, the Soviet Union had already made another leap ahead in the “space race” with the August 1961 flight of cosmonaut Gherman Titov in Vostok 2. Titov made 17 orbits and spent more than 25 hours in space. To Soviet propagandists, the Soviet conquest of space was evidence of the supremacy of communism over capitalism. However, to those who worked on the Vostok program and earlier on Sputnik (which launched the first satellite into space in 1957), the successes were attributable chiefly to the brilliance of one man: Sergei Pavlovich Korolev. Because of his controversial past, Chief Designer Korolev was unknown in the West and to all but insiders in the USSR until his death in 1966. Born in the Ukraine in 1906, Korolev was part of a scientific team that launched the first Soviet liquid-fueled rocket in 1933. In 1938, his military sponsor fell prey to Soviet leader Joseph Stalin’s purges, and Korolev and his colleagues were also put on trial. Convicted of treason and sabotage, Korolev was sentenced to 10 years in a labor camp. The Soviet authorities came to fear German rocket advances, however, and after only a year Korolev was put in charge of a prison design bureau and ordered to continue his rocketry work. In 1945, Korolev was sent to Germany to learn about the V-2 rocket, which had been used to devastating effect by the Nazis against the British. The Americans had captured the rocket’s designer, Wernher von Braun, who later became head of the U.S. space program, but the Soviets acquired a fair amount of V-2 resources, including rockets, launch facilities, blueprints, and a few German V-2 technicians. By employing this technology and his own considerable engineering talents, by 1954 Korolev had built a rocket that could carry a five-ton nuclear warhead and in 1957 launched the first intercontinental ballistic missile. That year, Korolev’s plan to launch a satellite into space was approved, and on October 4, 1957, Sputnik 1 was fired into Earth’s orbit. It was the first Soviet victory of the space race, and Korolev, still technically a prisoner, was officially rehabilitated. The Soviet space program under Korolev would go on to numerous space firsts in the late 1950s and early ’60s: first animal in orbit, first large scientific satellite, first man, first woman, first three men, first space walk, first spacecraft to impact the moon, first to orbit the moon, first to impact Venus, and first craft to soft-land on the moon. Throughout this time, Korolev remained anonymous, known only as the “Chief Designer.” His dream of sending cosmonauts to the moon eventually ended in failure, primarily because the Soviet lunar program received just one-tenth the funding allocated to America’s successful Apollo lunar landing program. Korolev died in 1966. Upon his death, his i


Which was the first space probe to leave the solar system?

Space Today Online - Voyager spacecraft are leaving the Solar System NASA's Voyager probes carry messages for extraterrestrial civilizations: greetings from humans and whales, some of Earth's greatest music, brainwaves of a woman in love. Click to enlarge NASA artist concept of Voyager 1 and 2 NASA's Voyager 1 spacecraft is the most distant human-made object in the universe. Its twin, Voyager 2, has traveled to more planets than any other in history. The spacecraft twins, Voyager 1 and Voyager 2, were launched by NASA during the summer of 1977 from Cape Canaveral, Florida. Barring any fatal equipment failures, the Voyager twins are likely to survive and relay data from beyond the outer planets for many decades into the 21st century. Today, in a dark, cold, vacant neighborhood at the very edge of our Solar System, NASA's Voyager 1 deep space probe holds the record as the Earth explorer that has traveled farthest from home. Voyager 1 When Voyager I was launched in 1977 to study and photograph the giant outer planets of the Solar System, the robot ship was expected to survive just four years. However, like the battery advertising icon, the Energizer Bunny, the little spacecraft kept on going. For 25 years, the Pioneer 10 spacecraft led the way outbound, pressing the frontiers of exploration, but in 1998 the baton was passed from Pioneer 10 to Voyager 1, according to NASA's Jet Propulsion Laboratory (JPL), Pasadena, California. Voyagers Timeline SOURCES: NASA JPL , STO On Feb. 17, 1998, the Voyager 1 spacecraft cruised beyond the Pioneer 10 spacecraft and become the most distant human-created object in space. At that time, it was 6.5 billion miles from Earth. Pioneer 10 and Voyager 1 are headed in almost opposite directions away from the Sun. The twins, Voyager 1 and 2, opened new vistas for the human race by expanding our knowledge of Jupiter and Saturn. Voyager 2 then extended our great planetary adventure when it flew by Uranus and Neptune, becoming the only spacecraft ever to visit these worlds. (None has ever visited Pluto.) Voyager 1, now the most distant human-made object in the Universe, and Voyager 2, close on its heels, continue their ground-breaking journey with their current mission to study the region in space where the Sun's influence ends and the dark recesses of interstellar space begin. Voyager 1 is almost 70 times farther from the Sun than the Earth. Out there, the Sun is only 1/5,000th as bright as here on Earth. It is extremely cold, and there is little solar energy to keep the probe warm and to provide electrical power. The probe can continue to operate at such great distances from the Sun because it has radioisotope thermal electric generators (RTGs) that create electricity. The fact that the spacecraft is still returning data is a remarkable technical achievement. Voyager flight path. Voyager 1 was launched from Cape Canaveral on Sept. 5, 1977. It flew by Jupiter on March 5, 1979, and then Saturn on Nov. 12, 1980. Because its trajectory was designed to fly close to Saturn's large moon Titan, Voyager 1's path was bent northward by Saturn's gravity. That sent the spacecraft out of the Solar System's ecliptic plane -- the plane in which all the planets, except Pluto, orbit the Sun. On Feb. 17, 1998, Voyager 1 was departing the Solar System at a speed of 39,000 miles per hour. At the same time, Voyager 2 was 5.1 billion miles from Earth and was departing the Solar System at a speed of 35,000 miles per hour. Voyager 2 is heading in the opposite direction of Voyager I and traveling at a slightly slower speed. Pioneer 10 had been launched earlier, on March 2, 1972. Its official mission ended on March 31, 1997. However, NASA's Ames Research Center, Moffett Field, CA, intermittently receives science data from Pioneer as part of a training program for flight controllers. Low power. Voyager 1 was so far from Earth in 1998 that it took 9 hours 36 minutes for a radio signal traveling at the speed of light to reach Earth. Voyager's signal, produced by a 20 watt radio transmitter, is so faint that the amount of


What is almost halfway through its 10-billion-year life, will expand to become a red giant and then shrink to become a white dwarf?

Formation of Planetary Nebulae Home The Not-so-Ordinary Life of a Typical Star Scattered like diamond chips across the Cosmos, stars look deceptively serene to earthbound observers. However, nothing could be farther from true because each one is a creature of unimaginable violence. Constant and unchanging, the nighttime stellar canopy appears essentially the same to us as it did to the ancient Greeks. But, this perception is misleading because, like people, even stars follow a cycle of birth and death. A star, like our Sun, begins its life as a vast cloud of gas and dust drifting among the apparently empty spaces between the stars. These clouds of sparse material are truly immense and often span hundreds or thousands of light years in all directions. Even though they contain fewer atoms than the best vacuum on Earth, the total amount of material in an interstellar cloud, also known as its mass, is truly astronomical. Most of the stuff in one of these clouds is hydrogen, the simplest and most abundant element in the Universe, but they also contain other, more complex, elements, too. For example, the cloud of dust and gas that formed our Sun must have included material from a previous generation star that blew itself apart. We suspect this because our Sun, and all of its planets including Earth, contain heavy elements that could only have been forged in the heart of a larger, long gone star that went supernova. Stars, like factories, create complex elements from hydrogen and release radiation as a by-product of their creation. The life cycle of a typical star like our Sun. Illustration credit: Wikipedia For billions of years interstellar clouds wander more or less aimlessly between their starry relatives until they receive a gravitational nudge, possibly from a nearby exploding star or the close passing of another galaxy. Significantly, once the cloud is pushed, events take on a life of their own and the material begins to contract inward under its own massive weight. As the dust particles and gas molecules move toward the cloud's center, they inevitably begin bumping into each other. Like rubbing your hands together, this generates heat. Stellar womb- am artist's impression of the central region inside an interstellar cloud where gravity is forging new stars. Illustration credit: M. Kornmesser/ESO Over time, these molecular collisions became more frequent. Eventually, the core of the cloud becomes so squeezed by gravity that pressures exceeded billions of atmospheres and temperatures reach over 50 million degrees. At this temperature, hydrogen nuclei collide with such speed, a thermonuclear reaction, known as fusion, is triggered. Fusion is the same process released when a hydrogen bomb is exploded. However, the amount of energy produced by a star is billions of times greater than any man-made nuclear weapon. When fusion commences, hydrogen is converted into the next heaviest element (helium) and a tremendous amount of energy is released in the form of photons. As the photons rush from the core of the cloud, they push back on the inward pressure of gravity, which is still trying to compress the cloud, until an equilibrium is achieved and the cloud's collapse ceases. Eventually the photons escape into space as visible light and other forms of invisible radiation and the star is born. Thus, a star is a balance between the unrelenting inward pull of gravity and the ongoing thermonuclear explosion pushing back from its core. Phase One- Nothing lasts forever Although, most of a star's volume is comprised of hydrogen, hydrogen can only be fused into helium at its core and all stars eventually deplete their central store of hydrogen. Thus, the balance that creates a star is only temporary. For example, although our Sun is supremely important to our existence, it is only an average star, about halfway through its 10 billion year life-cycle. Stars with less mass require less thermonuclear energy at their cores to counter balance the force of gravity, therefore they are cooler and shine for a longer period of time. Converse


Which planet orbits the Sun four times in the time it takes the Earth to go round once?

How Long it Takes for Each Planet to Orbit the Sun How Long it Takes for Each Planet to Orbit the Sun How Long it Takes for Each Planet to Orbit the Sun If one was asked the questions, οΏ½How long is a day?οΏ½ and οΏ½How long is a year?οΏ½ they would probably be very offended by such a simple question. A day is 24 hours, while a year is 365 days long, 366 during a leap year. In the basic sense, this answer would be correct, but the answer really only applies to Earth. On different planets, there are very different times of what constitutes a οΏ½day,οΏ½ which is the time it takes for a planet to complete one turn of its axis and a οΏ½year,οΏ½ which equivocates to the time it takes a planet to completely orbit around the sun. Planets that are closer to the sun do not take as long to complete their orbit and subsequently have shorter years than our planet. Alternatively, planets that are far away, such as Neptune or Saturn, take a very long time to completely orbit around the sun. Interestingly enough however, it seems to be the farther a planet is away from the sun, the faster they can complete a turn of their access. This means that although far reaching planets have longer years, their days are actually shorter than EarthοΏ½s. In terms of the four closest planets to the sun, excluding Earth, it can be seen how distance from the planet effects the time it takes for each planet to orbit the sun. Mercury, the first planet in our solar system can completely orbit around the sun in a mere 88 Earth Days, but nearly takes 60 days to complete a turn of its axis. Venus, which is the closet planet to Earth, takes 224 days to orbit around the sun. Oddly enough Venus takes longer to complete a rotation of its axis, 243 days, than it does to completely orbit the sun. Mars, one of the closest planets to Earth in size takes around 686.97 days to orbit around the earth and has a nearly identical day of 24.3 hours. The last four planets of the sun, demonstrate the immense effect of distance on the time it takes for a planet to rotate around the sun. Jupiter, the solar systemοΏ½s largest planet, takes 4,331.572 days to orbit around the sun, but the fast turning planet only takes 9.8 hours to completely rotate on its axis. Saturn takes more than double the time of Jupiter to orbit the sun with a time of 10,832.33 days, but has nearly an identical time to rotate on its axis with 10.2 hours. Uranus and Neptune are the two farthest planets from the sun and the time it takes for them to orbit around the sun reflects this. Uranus takes 30,7999.09 days to orbit around the sun, which is impressive but cannot compare to the 60,190 days it takes Neptune to complete the same task. However, Uranus and Neptune have comparable rotation times of 17.14 and 16 hours respectively. Next time youοΏ½re asked about how long a year or a day is, make sure to not fall into the boring perspective of only thinking about your planet. Giving the answer that a year on Neptune is more than 60,000 days or a day on Jupiter is less than 10 hours is a lot more interesting.


Which is the largest moon in the solar system?

Jupiter's Moon Ganymede - Universe Today   Universe Today by Matt Williams In 1610, Galileo Galilei looked up at the night sky through a telescope of his own design . Spotting Jupiter, he noted the presence of several “luminous objects” surrounding it, which he initially took for stars. In time, he would notice that these “stars” were orbiting the planet, and realized that they were in fact Jupiter’s moons – which would come to be named Io , Europa , Ganymede and Callisto . Of these, Ganymede is the largest, and boasts many fascinating characteristics. In addition to being the largest moon in the Solar System, it is also larger than even the planet Mercury. It is the only satellite in the Solar System known to possess a magnetosphere, has a thin oxygen atmosphere, and (much like its fellow-moons, Europa and Callisto) is believed to have an interior ocean. Discovery and Naming: Though Chinese astronomical records claim that astronomer Gan De may have spotted a moon of Jupiter (probably Ganymede) with the naked eye as early as 365 BCE, Galileo Galilei is credited with making the first recorded observation of Ganymede on January 7th, 1610 using his telescope. Together with Io, Europa and Callisto, he named them the “Medicean Stars” at the time – after his patron, the Grand Duke of Tuscany, Cosimo de’ Medici. Simon Marius, a German astronomer and contemporary of Galileo’s who claimed to have independently discovered Ganymede, suggested alternative names at the behest of Johannes Kepler. However, the names of Io, Europa, Ganymede and Callisto – which were all taken from classical mythology – would not come to formally be adopted until the 20th century. Illustration of Jupiter and the Galilean satellites. Credit: NASA Prior to this, the Galilean Moons were named Jupiter I through IV based on their proximity to the planet (with Ganymede designated as Jupiter III). Following the discovery of the moons of Saturn, a naming system based on that of Kepler and Marius was used for Jupiter’s moons. In Greek mythology, Ganymede was the son of King Tros (aka. Ilion), the namesake of the city of Troy (Ilium). Size, Mass and Orbit: With a mean radius of 2634.1 ± 0.3 kilometers (the equivalent of 0.413 Earths), Ganymede is the largest moon in the Solar System and is even larger than the planet Mercury. However, with a mass of 1.4819 x 10²³ kg (the equivalent of 0.025 Earths), it is only half as massive. This is due to Ganymede’s composition, which consists of water ice and silicate rock (see below). Ganymede’s orbit has a minor eccentricity of 0.0013, with an average distance (semi-major axis) of 1,070,400 km – varying from 1,069,200 km at periapsis to at 1,071,600 km apoapsis. Ganymede takes seven days and three hours to completes a single revolution. Like most known moons, Ganymede is tidally locked, with one side always facing toward the planet. Its orbit is inclined to the Jovian equator, with the eccentricity and inclination changing quasi-periodically due to solar and planetary gravitational perturbations on a timescale of centuries. These orbital variations cause the axial tilt to vary between 0 and 0.33°. Ganymede has a 4:1 orbital resonance with Io and a 2:1 resonance with Europa. Ganymede is the largest satellite in our solar system, larger than Mercury and Pluto, and three-quarters the size of Mars. Credit: NASA/JPL Essentially, this means that Io orbits Jupiter four times (and Europa twice) for every orbit made by Ganymede. The superior conjunction between Io and Europa occurs when Io is at periapsis and Europa is at apoapsis, and the superior conjunction between Europa and Ganymede occurs when Europa is at periapsis. Such a complicated resonance (a 4:2:1 resonance) is called the Laplace Resonance . Composition and Surface Features: With an average density of 1.936 g/cm3, Ganymede is most likely composed of equal parts rocky material and water ice. It is estimated that water ice constitutes 46–50% of the moon’s mass (slightly lower than that of Callisto) with the possibility of some additional volatile ices such as ammonia being


Where, theoretically, might one find objects squeezed to an infinite density?

Non-Singular Black Holes - One Universe at a Time One Universe at a Time In Black Holes by Brian Koberlein 13 May 2014 4 Comments The basic model of a black hole can be summed up as follows: gravity wins. The root cause of all black holes—be they tiny primordial black holes, solar mass black holes, or supermassive galactic black holes—is gravity. Squeeze enough mass into a small enough volume and gravity does the rest. The problem (at least according to general relativity) is that gravity does its job too well. Once matter enters a black hole, it simply cannot resist the pull of gravity. As a result all the matter within a black hole is squeezed down to a point of zero volume and infinite density, known as a singularity. Black hole singularities have long been the bugaboo of gravitational physics. They cause several problems, not the least of which is that the laws of physics as we understand them break down near the singularity. As a result there has been a lot of research on trying to eliminate singularities from our theoretical models. One way to get around singularities is by simply ignoring them. When black holes form, they become enclosed by an event horizon. A black hole’s event horizon is a kind of cosmic roach motel. Matter and energy can fall into a black hole, but anything that crosses the event horizon is forever stuck inside. Since the singularity always resides within the event horizon, we can never observe it from the outside. The singularity remains safely hidden from view. Roger Penrose even went so far as to propose the cosmic censorship hypothesis, which argues that every singularity must be enclosed by an event horizon, which hides it from the universe. But this hypothesis has never been proven in general, and several theoretical counter-examples (known as naked singularities) have been found. It would seem then that simply hiding singularities doesn’t solve the problem. Another approach to the problem is to find a mechanism by which the singularity never forms in the first place. Most of the effort in this area has been to find patchwork solutions to Einstein’s equations for general relativity. That is, patch together a black hole solution outside the event horizon (the exterior solution) with a non-singular solution inside the event horizon (the interior solution). By mathematically sewing the two solutions together, one gets a non-singular black hole. These solutions demonstrate that non-singular black holes are theoretically possible, but they say nothing about how such a black hole might form. Recently, however, Mbonye and Kazanas have found an exact solution to Einstein’s equations which contains no central singularity . Mbonye and Kazanas arrived at their solution by assuming a black hole contains exotic matter. Exotic matter is a theoretical material which has a negative energy density instead of the usual positive energy density. This negative energy density means that exotic matter can hold its own against gravity. When ordinary matter is squeezed by gravity, its energy density goes up. This higher energy density means gravity squeezes even more strongly, which means an even higher energy density, and so on. It is this feedback loop which means that gravity wins in the end. The harder gravity squeezes, the harder it can squeeze, until all that remains is the singularity. But exotic matter works differently. When gravity squeezes on exotic matter, its energy density goes down. This means gravity can’t win no matter how hard it tries, and it is impossible to form a singularity. What Mbonye and Kazanas have shown is that exotic matter allows for the creation of non-singular black holes. Mbonye and Kazanas don’t specify what this exotic matter is, but their formulation implies one possible candidate: dark energy. We don’t know what dark energy is, but we do know two things: it cannot be regular matter, and it has a negative energy density. Mbonye and Kazanas haven’t proven that their exotic matter is dark energy, but their work points to the idea that maybe, just maybe, one of newest mysteries o


Titan, Largest Moon of Saturn, Explained (Infographic) Find out the facts about Titan's heavy atmosphere, lakes of hydrocarbons and the possibility of life. Credit: Karl Tate, SPACE.com contributor   Discovered in the year 1655, Titan is the largest of Saturn’s 62 charted moons. Titan is the only moon in the solar system with a dense atmosphere and stable bodies of liquid on its surface. The environment on Titan is deadly to human life, with a toxic atmosphere consisting mostly of nitrogen and methane. The surface temperature is minus 290 degrees F (minus 179 degrees C). Titan, 3,200 miles (5,150 kilometers) in diameter, is the second-largest moon in the solar system, one-and-a-half times the size of Earth’s moon . Titan is larger than the planet Mercury and is three-quarters the size of Mars. [ Amazing Photos of Titan ] In 2005, the Huygens lander revealed the surface of Titan is a wasteland of water ice and frozen hydrocarbons. Despite its lack of liquid water, some scientists believe Titan may support life, now or in the distant future when the sun’s heat increases. A rain of liquid ethane and methane falls to form lakes, making Titan the only planet or moon apart from Earth known to have liquid on its surface. In addition, some scientists think Titan may have large sub-surface oceans of liquid ammonia. Radar images of Titan’s north polar region show presumed lakes of liquid hydrocarbons.


Which is the largest planet in the solar system?

What is the Biggest Planet in the Solar System? - Universe Today   Universe Today What is the Biggest Planet in the Solar System? Article Updated: 23 Dec , 2015 by Matt Williams Ever since the invention of the telescope four hundred years ago, astronomers have been fascinated by the gas giant of Jupiter. Between it’s constant, swirling clouds, its many, many moons, and its Giant Red Spot, there are many things about this planet that are both delightful and fascinating. But perhaps the most impressive feature about Jupiter is its sheer size. In terms of mass, volume, and surface area, Jupiter is the biggest planet in our Solar System by a wide margin. But just what makes Jupiter so massive, and what else do we know about it? Size and Mass: Jupiter’s mass, volume, surface area and mean circumference are 1.8981 x 1027 kg, 1.43128 x 1015 km3, 6.1419 x 1010 km2, and 4.39264 x 105 km respectively. To put that in perspective, Jupiter diameter is roughly 11 times that of Earth, and 2.5 the mass of all the other planets in the Solar System combined. But, being a gas giant, Jupiter has a relatively low density – 1.326 g/cm3 – which is less than one quarter of Earth’s. This means that while Jupiter’s volume is equivalent to about 1,321 Earths, it is only 318 times as massive. The low density is one way scientists are able to determine that it is made mostly of gases, though the debate still rages on what exists at its core (see below). Composition: Jupiter is composed primarily of gaseous and liquid matter. It is the largest of the gas giants, and like them, is divided between a gaseous outer atmosphere and an interior that is made up of denser materials. It’s upper atmosphere is composed of about 88–92% hydrogen and 8–12% helium by percent volume of gas molecules, and approx. 75% hydrogen and 24% helium by mass, with the remaining one percent consisting of other elements. This cut-away illustrates a model of the interior of Jupiter, with a rocky core overlaid by a deep layer of liquid metallic hydrogen. Credit: Kelvinsong/Wikimedia Commons The atmosphere contains trace amounts of methane, water vapor, ammonia, and silicon-based compounds as well as trace amounts of benzene and other hydrocarbons. There are also traces of carbon, ethane, hydrogen sulfide, neon, oxygen, phosphine, and sulfur. Crystals of frozen ammonia have also been observed in the outermost layer of the atmosphere. The interior contains denser materials, such that the distribution is roughly 71% hydrogen, 24% helium and 5% other elements by mass. It is believed that Jupiter’s core is a dense mix of elements – a surrounding layer of liquid metallic hydrogen with some helium, and an outer layer predominantly of molecular hydrogen. The core has also been described as rocky, but this remains unknown as well. In 1997, the existence of the core was suggested by gravitational measurements, indicating a mass of from 12 to 45 times the Earth’s mass, or roughly 4%–14% of the total mass of Jupiter. The presence of a core is also supported by models of planetary formation that indicate how a rocky or icy core would have been necessary at some point in the planet’s history in order to collect its bulk of hydrogen and helium from the protosolar nebula. However, it is possible that this core has since shrunk due to convection currents of hot, liquid, metallic hydrogen mixing with the molten core. This core may even be absent now, but a detailed analysis is needed before this can be confirmed. The Juno mission , which launched in August 2011, is expected to provide some insight into these questions, and thereby make progress on the problem of the core. The temperature and pressure inside Jupiter increase steadily toward the core. At the “surface”, the pressure and temperature are believed to be 10 bars and 340 K (67 °C, 152 °F). At the “phase transition” region, where hydrogen becomes metallic, it is believed the temperature is 10,000 K (9,700 °C; 17,500 °F) and the pressure is 200 GPa. The temperature at the core boundary is estimated to be 36,000 K (35,700 °C; 64,300 °F) and th


What is the smallest planet in the solar system?

What is the Smallest Planet in the Solar System? - Universe Today   Universe Today What is the Smallest Planet in the Solar System? Article Updated: 24 Dec , 2015 by Fraser Cain The smallest planet in the Solar System is Mercury (the biggest planet is Jupiter). For the longest time, the smallest planet was considered to be Pluto, but now Pluto isn’t a planet any more, so we’re back to Mercury. Mercury measures 4879 km along its equator. Just for comparison, Earth is 12,742 km across. So Mercury is only 38% the diameter of Earth. In terms of volume, it’s even less. Mercury has only 0.05 the volume of the Earth. In other words, if the Earth was a hollow shell, you could fit 20 Mercurys inside with room to spare. Even though it’s very small, Mercury is extremely dense. It’s composed mostly of iron and rock, and so it has a density of 5.4 grams per cubic centimeter. Only Earth has a higher density, and that’s partly due to our larger size compressing down the interior. If Mercury were the same size as Earth, it would be much denser. If you could stand on the surface of Mercury, you would experience 38% of Earth’s gravity. Even thought Mars is a larger planet, you would experience more gravity on Mercury because it’s so dense. And here’s another take on the smallest planet in the Solar System , and here’s a link to NASA’s Solar System Exploration Guide . We have recorded a whole series of podcasts about the Solar System at Astronomy Cast . Check them out here.


Which is the brightest comet in the solar system?

Age of Comets Article, Orbit Information, Solar System Facts -- National Geographic No telescope was needed to see comet Hyakutake above the Palomar Observatory in San Diego County, California, as it came within 9.3 million miles (15 million kilometers) of Earth in 1996. Photograph by Don Bartletti Written by William Newcott Republished from the pages of National Geographic magazine Whistling and moaning, a 50-mile-an-hour (80-kilometer-an-hour) wind whipped among the telescope domes atop Kitt Peak. Just a few feet below, turning gray in the dusk, slid a river of clouds that had been rising and dropping all day. And high above, comet Hale-Bopp hung suspended like a feathery fishing lure, its tail curving off a bit, as if blown to the side by the punishing wind. One by one, stars winked on in a darkening sky. In each of the telescope domes, teams of astronomers prayed that the wind would drop below 40 miles per hour (64 kilometers an hour), the point at which they'd be able to open the sliding doors and get back to work. The sky turned indigo. Then black. Viewed from the summit, 6,873 feet (2,095 meters) above Arizona's Sonoran Desert, Hale-Bopp's bright dust tail, along with a dimmer, all but transparent blue one, seemed to grow by degrees. Among the brightest comets ever seen, Hale-Bopp had been visible for months from midtown Manhattan, of all places. But here, on a moonless night in the mountains in the desert, the length of Hale-Bopp's tail became visible—a wispy, delicate veil. Along with eclipses, comets have been the most feared and admired sky spectacles of all. But while astronomers have been able to predict eclipses for thousands of years, only in the 1700s was a comet's return correctly predicted, by Edmond Halley. Some comets swing around the sun every few years. Others, like Hale-Bopp, may take thousands of years. Most can be seen only with a telescope. But every once in a while—a few times a century, perhaps—an impressive one is visible to the naked eye. And in the past two years the world has witnessed not one but two of them. Hyakutake in 1996 had one of the longest tails on record, stretching more than halfway across the sky; Hale-Bopp in 1997 had one of the most brilliant heads, nearly as bright as the star Sirius. Add the Jupiter crash of comet Shoemaker-Levy in 1994, Halley's most recent visit in 1986, vivid comet West in 1976, and the scientifically signifiant—if visually disappointing—Kohoutek in 1973-74, and you could say that we are indeed living in the age of comets. Hovering in the most fragile of gravitational balances, a fleet of dirty, lumpy snowballs numbering in the trillions is barely held in orbit by the pull of the sun. They are stored in the Oort cloud, a huge, diffuse sphere of cometary nuclei in the far reaches of the solar system. Close to the sun, yet still beyond Neptune, circle what may well be their brethren, in a great disk called the Kuiper belt. Comets are leftovers, scraps of material that didn't make it to planethood in the events creating our solar system. Once, many astronomers believe, the solar system was full of comet nuclei, chunks of ice and dust left over from the formation of the sun. Most clumped together to form planets, leaving a relative handful—averaging perhaps a few miles wide, with temperatures as low as minus 400 degrees Fahrenheit (minus 240 degrees Celsius)—as time capsules of the early solar system. They orbit in a perpetual deep freeze until some subtle gravitational nudge upsets the delicate balance. Then the great fall begins. Imperceptibly at first, a snowball drifts toward the sun and steadily accelerates. As solar radiation heats the comet, the ice within sublimates, escaping as gas from vents at the surface. Sometimes jets of sublimating ice whirl off the rotating comet nucleus like a fireworks pinwheel. Dust trapped in the ice breaks free. Pushed back by the pressure of the sun's radiation, the dust streams out behind the comet in what appears as a fiery tail. Now the comet is among the fastest things in the solar system. It whizzes past the inne


What would you find if you travelled to the centre of the solar system?

If Jupiter and Saturn are gas giants, could you fly straight through them? Audio recording of Dr. Marc reading this page. Click play to hear me read this to you! Our friends at the W.A. Gayle Planetarium in Montgomery, Alabama, are curious to know, if Jupiter and Saturn are gas giants, could you fly straight through them? We think of a gas as something very . . . well, airy. After all, air is the gas we all know and love. We breathe it and fly planes right through it with no trouble. So it makes sense to think that a gas planet must be like a big, airy cloud floating out in space. But take another look at Jupiter and Saturn—or pictures of them. Notice how round they are. You will never see a cloud on Earth so nearly spherical. Why are Jupiter and Saturn so round if they are just gas? For that matter, why are any planets round? Well, the short answer is—gravity. Gravity causes all matter to be pulled toward all other matter. Let's think about this in more detail. When the planets were first forming, the solar system was a big, swirling disk of gas and dust, with the newborn Sun at the center. Bits of dust and clouds of gas were attracted to each other because of gravity. As these bits and clouds clumped, they attracted still more matter in their neighborhood and grew larger and larger until there was no longer any stray material nearby for them to attract. The growing planets were like big solar system vacuum cleaners, sweeping up all the debris in their paths. And they became round because gravity pulls equally toward the center of large masses such as planets, so anything sticking out gets pulled back to make a ball. The bigger a planet becomes, the heavier is the material weighing down on its center. Think of how it feels to dive under water. If you are wearing a face mask, you notice that as you dive deeper, the mask presses harder and harder on your face. Also, your ears start feeling the pressure even at 2 or 3 meters (5 or 10 feet) below the surface. The pressure you feel on your body is due to the weight of the water above you. The deeper you go, the heavier the water above you and so the greater the pressure on your body. Even on Earth's surface, each square inch of your body experiences 14.7 pounds of pressure due to the weight of the atmosphere above you. If you could dive down to the center of Earth, the pressure on your body would be about 3.5 million times as great! The center of Jupiter is more than 11 times deeper than Earth's center and the pressure may be 50 million to 100 million times that on Earth's surface! The tremendous pressure at the center of planets causes the temperatures there to be surprisingly high. At their cores, Jupiter and Saturn are much hotter than the surface of the Sun! Strange things happen to matter under these extraordinary temperatures and pressures. Hydrogen, along with helium, is the main ingredient of Jupiter's and Saturn's atmospheres. Deep in their atmospheres, the hydrogen turns into a liquid. Deeper still, the liquid hydrogen turns into a metal! But what's at the very center of these planets? The material becomes stranger and stranger the deeper you go. Scientists do not understand the properties of matter under the extreme environments inside Jupiter and Saturn. Many different forces and laws of nature are at work, and the conditions inside these planets are very difficult to create in a laboratory here on Earth. But you can be sure that you wouldn't be able to fly through these bizarre materials! As we now know, the gas giants are much more than just gas.


How many planets are there in the solar system?

How Many Planets are in the Solar System? - Universe Today   Universe Today How Many Planets are in the Solar System? Article Updated: 16 Oct , 2016 I’m just going to warn you, this is a controversial topic. Some people get pretty grumpy when you ask: how many planets are in the Solar System? Is it eight, ten, or more? I promise you this, though, we’re never going back to nine planets… ever. When many of us grew up, there were nine planets in the Solar System. It was like a fixed point in our brains. As kids, memorizing this list was an early right of passage of nerd pride: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. But then in 2005, Mike Brown discovered Eris, an icy object thought to be about the same size as Pluto, out beyond its orbit. That would bring the total number of planets to ten. Right? There’s no turning back, textbooks would need to be changed. In order to settle the dispute, the International Astronomical Union met in 2006, and argued for, and against Pluto’s planethood. Some astronomers advocated widening the number of planets to twelve, including Pluto, its moon Charon, the Asteroid Ceres, and the newly discovered Eris. In the end, they changed the definition of what makes a planet, and sadly, Pluto doesn’t make the cut: Here are the new requirements of planethood status: A planet has to orbit the Sun. Okay fine, Pluto does that. A planet needs enough gravity to pull itself into a sphere. Okay, spherical. Pluto’s fine there too. A planet needs to have cleared out its orbit of other objects. Uh oh, Pluto hasn’t done that. For example, planet Earth accounts for a million times the rest of the material in its orbit, while Pluto is just a fraction of the icy objects in its realm. The final decision was to demote Pluto from planet to dwarf planet. But don’t despair, Pluto is in good company. Ceres. Image credit: NASA There’s Ceres, the first asteroid ever discovered, and the smallest of the dwarf planets. The surface of Ceres is made of ice and rock, and it might even have a liquid ocean under its surface. NASA’s Dawn mission is flying there right now to give us close up pictures for the first time. Haumea, named after the Hawaiian goddess of fertility, is about a third the mass of Pluto, and has just enough gravity to pull itself into an ellipsoid, or egg shape. Even though it’s smaller, it’s got moons of its own. Makemake. Credit: NASA Makemake, a much larger Kuiper belt object, has a diameter about two-thirds the size of Pluto. It was discovered in 2005 by Mike Brown and his team. So far, Makemake doesn’t seem to have any moons. Eris is the most massive known dwarf planet, and the one that helped turn our definition of a planet upside-down. It’s 27% more massive than Pluto and the ninth most massive body that orbits the Sun. It even has a moon: Dysnomia. Pluto. Credit: ESO And of course, Pluto. The founding member of the dwarf family. Want an easy way to remember the eight planets, in order? Just remember this mnemonic: my very excellent mother just served us noodles. For all you currently writing angry tweets to Mike Brown , hold on a sec. Changing Pluto’s categorization is an important step that really needed to happen. The more we discover about our Universe, the more we realize just how strange and wonderful it is. When Pluto was discovered 80 years ago, we never could have expected the variety of objects in the Solar System. Categorizing Pluto as a dwarf planet helps us better describe our celestial home. So, our Solar System now has eight planets, and five dwarf planets. Podcast (audio): Download (Duration: 3:35 — 3.3MB) July 18, 2008 at 8:57 PM There are 12 planets in the solar system–Mercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto, MakeMake, and Eris. It’s not the International Astronomical Union but four percent of that group that voted on excluding Pluto in a sloppy, nonsensical definition that states a dwarf planet is not a planet at all. The requirement that an object clear its orbit to be considered a planet is vague and if applied lit


Which planet is named after the Roman goddess of love?

Planet Venus Facts: A Hot, Hellish & Volcanic Planet Planet Venus Facts: A Hot, Hellish & Volcanic Planet By Charles Q. Choi, Space.com Contributor | November 4, 2014 09:01pm ET MORE Credit: NASA Venus, the second planet from the sun, is named for the Roman goddess of love and beauty. The planet — the only planet named after a female — may have been named for the most beautiful deity of her pantheon because it shone the brightest of the five planets known to ancient astronomers. In ancient times, Venus was often thought to be two different stars, the evening star and the morning star — that is, the ones that first appeared at sunset and sunrise. In Latin, they were respectively known as Vesper and Lucifer. In Christian times, Lucifer, or "light-bringer," became known as the name of Satan before his fall. Physical characteristics Venus and Earth are often called twins because they are similar in  size , mass, density,  composition  and gravity. However, the similarities end there. [ Photos: Venus, the Mysterious Planet Next Door ]  Venus is the hottest world in the solar system. Although Venus is not the planet closest to the sun, its dense atmosphere traps heat in a runaway version of the greenhouse effect that warms Earth. As a result,  temperatures on Venus  reach 870 degrees Fahrenheit (465 degrees Celsius), more than hot enough to melt lead. Probes that scientists have landed there have survived only a few hours  before being destroyed . Venus has a  hellish atmosphere  as well, consisting mainly of carbon dioxide with clouds of sulfuric acid, and scientists have only detected trace amounts of water in the atmosphere. The atmosphere is heavier than that of any other planet, leading to a surface pressure 90 times that of Earth. The surface of Venus is extremely dry. During its evolution, ultraviolet rays from the sun evaporated water quickly, keeping it in a  prolonged molten state . There is no liquid water on its surface today because the scorching heat created by its ozone-filled atmosphere would cause any to boil away. Roughly two-thirds of the Venusian surface is covered by flat, smooth plains that are marred by thousands of volcanoes, some which are  still active today , ranging from about 0.5 to 150 miles (0.8 to 240 kilometers) wide, with lava flows carving long, winding canals up to more than 3,000 miles (5,000 km) in length, longer than on any other planet. Six mountainous regions make up about one-third of the Venusian surface. One mountain range, called Maxwell, is about 540 miles (870 km) long and reaches up to some 7 miles (11.3 km) high, making it the highest feature on the planet. Venus also possesses a number of surface features unlike anything on Earth. For example, Venus has coronae, or crowns — ringlike structures that range from roughly 95 to 360 miles (155 to 580 km) wide. Scientists believe these formed when hot material beneath the crust rises up, warping the planet’s surface. Venus also has tesserae, or tiles — raised areas in which many ridges and valleys have formed in different directions. With conditions on Venus that could be described as infernal, the ancient name for Venus — Lucifer — seems to fit. However, this name did not carry any fiendish connotations; Lucifer means "light-bringer," and when seen from Earth, Venus is brighter than any other planet or even any star in the night sky because of its highly reflective clouds and its closeness to our planet. Venus takes 243 Earth days to rotate on its axis, by far the slowest of any of the major planets, and because of this sluggish spin, its metal core cannot generate a magnetic field similar to Earth's. Orbital characteristics If viewed from above, Venus rotates on its axis the opposite way that most planets rotate. That means on Venus, the sun would appear to rise in the west and set in the east. On Earth, the sun appears to rise in the east and set in the west. The Venusian year — the time it takes to orbit the sun — is about 225 Earth days long. Normally, that would mean that days on Venus would be longer than years. However, becau


What kind of extraterrestrial objet has been named after the 17th-century astronomer Edmond Halley?

Astronomy - 2 | Britannica.com Astronomy science that encompasses the study of all extraterrestrial objects and phenomena. Browse Subcategories: (243) Displaying 1 - 100 of 800 results 51 Pegasi fifth-magnitude star located 48 light-years away from Earth in the constellation Pegasus, the first sunlike star confirmed to possess a planet. 51 Pegasi, which has physical properties (luminosity and temperature, for example) very similar to those of... 61 Cygni first star whose distance from Earth was measured. German astronomer Friedrich Wilhelm Bessel obtained a value of 10.3 light-years in 1838; the European Space Agency satellite Hipparcos made much more accurate distance measurements than ground-based... Abūʾl-Wafāʾ a distinguished Muslim astronomer and mathematician, who made important contributions to the development of trigonometry. Abūʾl-Wafāʾ worked in a private observatory in Baghdad, where he made observations to determine, among other astronomical parameters,... accretion disk a disklike flow of gas, plasma, dust, or particles around any astronomical object in which the material orbiting in the gravitational field of the object loses energy and angular momentum as it slowly spirals inward. In astrophysics, the term accretion... Achernar brightest star in the constellation Eridanus and the ninth brightest star in the sky. Achernar (Arabic for “end of the river”) is 144 light-years from Earth. It is a binary star with a B-type star, Achernar A, as its primary and a much fainter A-type... Adams, John Couch British mathematician and astronomer, one of two people who independently discovered the planet Neptune. On July 3, 1841, Adams had entered in his journal: “Formed a design in the beginning of this week of investigating, as soon as possible after taking... Adams, Walter American astronomer who is best known for his spectroscopic studies. Using the spectroscope, he investigated sunspots and the rotation of the Sun, the velocities and distances of thousands of stars, and planetary atmospheres. Born of missionary parents... Airy, Sir George Biddell English scientist who was astronomer royal from 1835 to 1881. Airy graduated from Trinity College, Cambridge, in 1823. He became Lucasian professor of mathematics at Cambridge in 1826 and Plumian professor of astronomy and director of the Cambridge observatory... Aitken, Robert Grant American astronomer who specialized in the study of double stars, of which he discovered more than 3,000. From 1891 to 1895 Aitken was professor of mathematics and astronomy at the University of the Pacific, Stockton, Calif. In 1895 he joined the staff... Akiyama Toyohiro Japanese journalist and television reporter, the first Japanese citizen and the first journalist to travel into space. Akiyama was also the first fare-paying civilian passenger (nonprofessional astronaut) to participate in a spaceflight. Akiyama earned... Al Saud, Sultan ibn Salman the first Saudi Arabian citizen, the first Arab, the first Muslim, and the first member of a royal family to travel into space. Educated in the United States, Sultan received a degree in mass communications from the University of Denver (Colorado) and... al-Ḥanafī, ʿAlam al-Dīn Egyptian mathematician, astronomer, and engineer. He wrote a treatise on Euclid’s postulates, built water mills and fortifications on the Orontes River, and constructed the second-oldest existing Arabic celestial globe. Alcock, George Eric Deacon British schoolteacher and amateur astronomer who was ranked as one of the world’s finest amateur astronomers; his 10 major discoveries exceeded the previous record of 8 discoveries made by 18th-century English astronomer Caroline Herschel. Despite the... Alcor from Arabic “Faint One” star with apparent magnitude of 4.01. Alcor makes a visual double with the brighter star Mizar in the middle of the handle of the Big Dipper (Ursa Major). The two are 1.2 light-years apart and may be gravitationally bound to each... Aldebaran Arabic “The Follower” reddish giant star in the constellation Taurus. Aldebaran is one of the 15 brightest stars,


What was the first artificial satellite?

Sputnik NASA Main Page Multimedia Interactive Feature on 50th Anniversary of the Space Age Sputnik and The Dawn of the Space Age History changed on October 4, 1957, when the Soviet Union successfully launched     Sputnik I. The world's first artificial satellite was about the size of     a beach ball (58 cm.or 22.8 inches in diameter), weighed only 83.6 kg. or 183.9 pounds, and took about 98 minutes to orbit     the Earth on its elliptical path. That launch ushered in new political,     military, technological, and scientific developments. While the Sputnik     launch was a single event, it marked the start of the space age and the     U.S.-U.S.S.R space race.  The story begins in 1952, when the International Council of Scientific  Unions decided to establish July 1, 1957, to December 31, 1958, as the International  Geophysical Year (IGY) because the scientists knew that the cycles  of solar activity would be at a high point then. In October 1954, the council  adopted a resolution calling for artificial satellites to be launched during  the IGY to map the Earth's surface.  In July 1955, the White House announced plans to launch an Earth-orbiting satellite for the IGY and solicited proposals  from various Government research agencies to undertake development. In  September 1955, the Naval Research Laboratory's Vanguard proposal was chosen to represent the U.S. during the IGY.  The Sputnik launch changed everything. As a technical achievement, Sputnik  caught the world's attention and the American public off-guard. Its size  was more impressive than Vanguard's intended 3.5-pound payload. In addition,  the public feared that the Soviets' ability to launch satellites also translated  into the capability to launch ballistic missiles that could carry nuclear weapons from Europe to the U.S. Then the Soviets struck again; on November  3, Sputnik II was launched, carrying a much heavier payload, including  a dog named Laika.  Immediately after the Sputnik I launch in October, the U.S. Defense  Department responded to the political furor by approving funding for another  U.S. satellite project. As a simultaneous alternative to Vanguard, Wernher  von Braun and his Army Redstone Arsenal team began work on the Explorer project.  On January 31, 1958, the tide changed, when the United States successfully  launched Explorer I. This satellite carried a small scientific payload  that eventually discovered the magnetic radiation belts around the Earth,  named after principal investigator James Van Allen. The Explorer program  continued as a successful ongoing series of lightweight, scientifically  useful spacecraft.  The Sputnik launch also led directly to the creation of National  Aeronautics and Space Administration (NASA). In July 1958, Congress passed  the National  Aeronautics and Space Act (commonly called the "Space Act") , which  created NASA as of October 1, 1958 from the National Advisory Committee  for Aeronautics (NACA) and other government agencies.  Updated October 10, 2007


What is the name of the space shuttle destroyed in midair 28 Jan 1986?

Challenger Disaster Live on CNN - YouTube Challenger Disaster Live on CNN Want to watch this again later? Sign in to add this video to a playlist. Need to report the video? Sign in to report inappropriate content. Rating is available when the video has been rented. This feature is not available right now. Please try again later. Uploaded on Jul 24, 2007 January 28th, 1986 at 11:39am EDT - The Space Shuttle Challenger Explodes on its 10th flight during mission STS-51-L. The explosion occurred 73 seconds after liftoff and was actually the result of rapid deceleration and not combustion of fuel. CNN was the only national news station to broadcast the mission live, so thus what you are witnessing on this video is the only coverage of the disaster as it happened when it did. Approximately 17% of Americans witnessed the launch live, while 85% of Americans heard of the news within 1 hour of the event. According to a study, only 2 other times in history up to that point had news of an event disseminated so fast - the first being the announcement of JFK's assassination in 1963, the second being news spread among students at Kent State regarding the news of FDR's death in 1945. It has been estimated at the time that nearly 48% of 9-13 year olds witnessed the event in their classrooms, as McAuliffe was in the spotlight. The 25th Space Shuttle mission altered the history of manned space exploration and represented the first loss of an American crew during a space mission (Apollo 1 was during a training exercise). Christa McAuliffe was slated to be the first teacher in space for the Teacher in Space Program. As her maximum altitude was ~65,000ft (12.31 miles), she never made it to space. That title was given to Barbara Morgan of STS-118 aboard the shuttle Endeavour in August 2007, 22 and a half years after the Challenger Disaster. Morgan served as McAuliffe's backup during STS-51-L. As Morgan is now part of the Educator in Space Program, she will be credited as the first "educator" in space, to distinguish her from McAuliffe. Aboard Challenger during STS-51-L: Sharon Christa McAuliffe (Payload Specialist - Teacher in Space) Category