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A planet (from Greek πλανήτης, alternative form of πλάνης "wanderer") is a celestial body that is or was orbiting a star or stellar remnant and is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals. The term planet is ancient, with ties to history, science, mythology, and religion. The planets were originally seen by many early cultures as divine, or as emissaries of the gods. As scientific knowledge advanced, human perception of the planets changed, incorporating a number of disparate objects. In 2006, the International Astronomical Union officially adopted a resolution defining planets within the Solar System. This definition has been both praised and criticized, and remains disputed by some scientists. The planets were thought by Ptolemy to orbit the Earth in deferent and epicycle motions. Though the idea that the planets orbited the Sun had been suggested many times, it was not until the 17th century that this view was supported by evidence from the first telescopic astronomical observations, performed by Galileo Galilei. By careful analysis of the observation data, Johannes Kepler found the planets' orbits to be not circular, but elliptical. As observational tools improved, astronomers saw that, like Earth, the planets rotated around tilted axes, and some share such features as ice-caps and seasons. Since the dawn of the Space Age, close observation by probes has found that Earth and the other planets share characteristics such as volcanism, hurricanes, tectonics, and even hydrology. Since 1992, through the discovery of hundreds of planets around other stars, called extrasolar planets, scientists are beginning to understand that planets throughout the Milky Way Galaxy share characteristics in common with our own. As of January 2010, there are 423 known extrasolar planets, ranging from the size of gas giants to that of terrestrial planets. Planets are generally divided into two main types: large, low-density gas giants, and smaller, rocky terrestrials. Under IAU definitions, there are eight planets in the Solar System. In order of increasing distance from the Sun, they are the four terrestrials, Mercury, Venus, Earth, and Mars, then the four gas giants, Jupiter, Saturn, Uranus, and Neptune. Apart from the planets, the Solar System also contains at least five dwarf planets and hundreds of thousands of small solar system bodies. With the exception of Mercury and Venus, all planets are orbited by one or more natural satellites. From Wikipedia under the
GNU Free Documentation License Is it common to find planets orbiting around red dwarf stars to have habitable life? Q. I am not talking about other yellow stars like the sun. Just red ones. I heard the planet can be tide locked. The dark side is so cold it condenses gases. The daylight side is so hot it boils water. Is it always true that planets orbiting red dwarfs are tide locked? Asked by caltam84 - Mon Dec 24 19:47:04 2007 - - 11 Answers - 0 Comments A. No one has enough information to answer this question. My guess: Unlikely Answered by Cappo359 - Mon Dec 24 19:55:04 2007 What makes the planets to rotate around themselves while revolving around the sun? Q. Also why doesn't sun attract the planets, at least the inner ones like Mercury inside it that is,what keeps Mercury from clashing with sun? Asked by Santosh - Thu Nov 26 12:25:21 2009 - - 5 Answers - 0 Comments A. The important concept to remember here is angular momentum which is conserved! The sun was formed from a rotating cloud of gas and dust (proto-solar system). When the center of this cloud was big enough and the pressure high enough to start fusion, the star "turns on" creating the sun and thus the solar system. Everything else revolving around it maintains the same rotation if the geometry of the body is unchanged. If a planet had the ability of getting bigger or smaller (which could technically be possible with gas giants like Jupiter and Saturn, but we will never see such a scenario), the bigger the planet gets the slower would rotate and vice versa... angular momentum is conserved! Other things that would affect a rotation of a… [cont.] Answered by AstroGator - Thu Nov 26 15:01:22 2009 How does discovering new planets relate to government?
Q. Each week in my government class I have to write a summary on an article that relates to government. This week I wrote one on astronomers discovering four planets outside of our solar system. How does this relate to local, state, or federal government? Asked by Ash - Sun Nov 16 21:09:35 2008 - - 4 Answers - 0 Comments A. 1. If the astronomers or the search efforts were funded with tax dollars, then you have a government issue. 2. If any new government actions or programs are based on this new information, then you have a government issue. 3. If the parties funded in either of the above situations are in your state or locality, then it's a state and/or local issue for you. 4. If the "feds" throw a few million or more at any project, then that money goes to hire people, buy things, and build stuff. When they buy stuff, the money goes to whomever makes or sells that stuff. When they build stuff, someone gets paid for building stuff, and so on. Every time the money changes hands, somebody gets taxed and the whole cycle starts over. A little business goes a… [cont.] Answered by Mediocrates - Sun Nov 16 21:15:15 2008 From Yahoo Answer Search: "Planets"
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 news.google.com New York Times A great void extending infinitely in all directions, sparsely dotted by stars, planets and other heavenly bodies, booby-trapped by black holes and traversed ... and more » news.google.com Hot Hardware As the new year kicks off, LG is introducing the planet's first "portable, battery-operated mobile DTV in the United States," which is designed to receive ... and more » news.google.com Washington Post "We're finding new extra-solar planets every week," she said. "We now know microbes can live in extreme environments on Earth thought to be impossible for ... and more » From Google News Search: "Planets"  blirk.net 1200px x 1920px | 393.20kB [source page] cosmos 24 Keywords graphics planets stars cosmos  zappa.brainiac.com 449px x 481px | 114.60kB [source page] Battle of the Planets  vegoose.com 576px x 720px | 171.20kB [source page] Digable Planets 10 3 > 17 Jul 2007 18 49 185k Digable Planets 10 3 > 17 Jul 2007 18 49 174k Digable Planets 10 3 > 17 Jul 2007 18 49 171k Digable Planets 10 3 > 17 Jul 2007 18 48 168k From Yahoo Image Search: "Planets"  tonic.com David Bois ue, 05 Jan 2010 22:08:00 GM With the Kepler Mission's discovery of five . planets. , 2010 is continuing last year's brisk pace of discovering new...  utexas.edu Rebecca Johnson Mon, 04 Jan 2010 20:29:40 GM Kepler mission astronomers, including co-investigator Bill Cochran of The University of Texas at Austin, announced today the spaceborne telescope has found.  aajtv.com unknown ue, 05 Jan 2010 05:29:00 GM Washington : Nasa's Kepler space telescope has discovered five new . planets. beyond the solar system, the US space agency said Monday, just 10 months after Kepler launched into space to find Earth-like . planets. . ... From Google Blog Search: "Planets" |
Extrasolar Planets
Record Breaker: A Planet from the Early Universe
Arizona Search for Planets (ASP)