which is the biggest planet known to us?? Is it jupitar or diffrent. I heard there is one bigger than Jupitar.
491971
The largest "planet" by mass currently known is HD 168443 c, which orbits the star HD 168443, a sunlike star located 123.5 light years from our own solar system. HD 168443 c orbits its star at a distance of 2.87 AU (430.5 million km) and completes one orbit of its star every 1739.5 days. Its mass is known to be at least 17.1 times that of Jupiter, and is suspected to be 34 times that of Jupiter (there is, as you can see, a lot of uncertainty in the measurment). This means that technically, it's considered a small brown dwarf rather than a planet, although the distinction is somewhat academic.\n\nP.S. it's Jupiter, not Jupitar.
352109
Actually, the people who found it honestly want to have it called Xena.\n\nOn July 29, 2005, a Trans-Neptunian object called 2003 UB313 was announced, which on the basis of its magnitude and simple albedo considerations is assumed to be larger than Pluto. This caused its discoverers to call it the "10th planet" of the solar system, although there is no consensus yet on whether to call it a planet, and others consider the new discovery to be the strongest argument yet for demoting Pluto to the status of a minor planet.\n\nBut until then, it's being refered to as Planet X.
150101
The small size and weird, distant orbit makes it feel more or less like a stray double-moon. I'm not sure why it's considered a planet really - maybe it's the smaller body that rotates it, Charon, that makes us class it as a planet, maybe it's because we looked for a reason for the deviations in the planets orbits and prematurely labeled it planet. As for me, I do - mostly because Pluto is always mentioned as a planet.
17873
Unknown, of course. But the largest planet in our SOLAR SYSTEM is Jupiter.
871143
Largest known to date is the "puffy planet" HAT-P-1b orbiting the sunlike star ADS 16402 B, one of a binary pair of G0 V stars 450 light yeard away, in the constellation Lacerta. Our sun is of spectral class G2 V i.e. a little cooler than ADS 16402 B.\n\nHAT-P-1b has a radius of 1.36 x the radius of Jupiter. \n\nIt was discovered on 13 September 2006 and is 450 light years away. It has the lowest density of any known extrasolar planet. It also has the name Krais.\n\nIt was announced as follows:\n\n"Using small automated telescopes in Arizona and Hawaii, the HATNet project has detected an object transiting one member of the double star system ADS 16402 AB. This system is a pair of G0 main-sequence stars with age about 3 billion years, at a distance of ~139 parsecs and projected separation of ~1550 AU. The transit signal has a period of 4.46529 days."\n\nNote: Only the radii of transiting planets are known.
893643
Currently there are 182 known "exoplanets".  The large majority are Jupiter-sized or larger, and much closer to their Sun than the gas giants in our solar system are to our Sun.  Thus, the term "hot Jupiter" is used to describe these, big close exoplanets.\n\nWhile a variety of techniques exist to find exoplanets, the most common is looking for wobbles induced in the parent star by the planet's minor gravitational pull.  This technique means that we're biased towards finding planets which induce large wobbles in their parent star.  Large wobbles are produced by larger planets that are very close to their star...so the huge population of hot Jupiters we find is probably not representative of the true exoplanet distribution.
31095
The 10th planet was discovered last summer.\n\nJuly 29, 2005: "It's definitely bigger than Pluto." So says Dr. Mike Brown of the California Institute of Technology who announced today the discovery of a new planet in the outer solar system.\n\nThe planet, which hasn't been officially named yet, was found by Brown and colleagues using the Samuel Oschin Telescope at Palomar Observatory near San Diego. It is currently about 97 times farther from the sun than Earth, or 97 Astronomical Units (AU). For comparison, Pluto is 40 AU from the sun. \n\nThe planet's temporary name is 2003 UB313. A permanent name has been proposed by the discoverers to the International Astronomical Union, and they are awaiting the decision of this body before announcing the name.
57670
According to Wikipedia, the official designation of this "planet" is 2003 UB313.  Its discoverers claim that it is definitely larger than Pluto, and that it has at least one moon.\n\nThe name is not actually Xena, and this is simply a codename used by the discoverers, and has not been submitted to the International Astronomical Union for consideration as a real name for the planet.\n\nIt's roughly 20 percent larger than Pluto, I guess.  They can't disclose the name that they will be proposing for the planet.\n\nThere is a re-definition of the term "planet" going on right now by the IAU, so it is possible that this will turn out not to be considered an actual planet.\n\nMore info here: http://en.wikipedia.org/wiki/2003_UB313
667527
Nice links. I would think that Pluto is still a planet. Its mean radius relative to earth's radius is approximately 0.46. So the diameter at equator might be some 3600 miles. By comparison, a satellite like Nereid, which orbits the planet Neptune, is no more than 200 miles in diameter. At its size Pluto must be a planet.\nI am not sure about Sedna. If we think about the 10-th planet, or the "X" planet, it was thought to be three times as massive as Saturn, and nearly six billion miles from the earth. It looks to me that Sedna might not be our 10-th planet. But then again, perhaps we just have to wait and see.
523525
UB-313 (also known as "Xena"). This is the only "tenth planet" that has a moon and is larger than Pluto.\n\nThere are several other "planetoids" or "plutinos" including Sedna, Quaoar, Ixion, Varuna, and Orcus.
1114535
2003 UB-313 (tentatively named "Xena") was discovered, or more specifically, confirmed, back in 8-January 2005 and was the first TNO (Trans-Neptunian Object) discovered that was larger than Pluto.  There has been ongoing debate about whether to classify it as a planet or not.  Reciprocally, there is a counter-push claiming that if 2003 UB-313 were to not be classified as a planet, then Pluto should also be removed from the IAU's "official list".\n\nAs of today, though, Pluto is still a planet, and Xena is not.\n\nNeither are 90377 Sedna and 90482 Orcus, two more candidate planetoids.  Though these two are both smaller than Pluto and Xena, they are still of roughly spherical shape and similar composition.
75743
Twertyto's answer is the best! When I was just learning about astronomy I asked the same question. Someone told me a very simple answer that just might work for you:  A planet reflects light and a star creates it. That sounds simple enough for simpler times! But now welcome to the 21st century!!!\nBrown dwarfs are kind of the "animal" that bridges these two seemingly different objects. Astronomy is having a hard (but fun) time right now trying to decide exactly what a planet is- from the very large to the very small. Is an object 75 times the size of Jupiter a planet? 79 times? 81 times? No one seems to know. Do we call them planets or officially name them Brown Dwarfs. On the other side of the issue, is Pluto a planet? They just discovered a larger than Pluto object and several almost-the-size-of-Pluto objects out past Pluto's orbit. Are all of these planets? If Pluto's not a planet, but now has been discovered to have at least 3 moons (two new one's were just discovered recently), then what do we call it? \nThis has been a surprisingly tough answer for Astronomers as well, so not only is it a great question, but you- and everyone else- might have to stick around for a while for the difinitive answer!!!
1101184
2003UB313. Although its still not officially a "planet". Neither is Pluto for that matter. From what I know UB313 is an educated assumption made because of a variance in  Pluto's orbit. In other words something is causing Pluto to "move" a certain way along its orbit. It would definately take  a large celestial object to cause this to happen but Im not sure if it has definately been determined that its a planet
753879
Astronomers say they have discovered what appears to be an entirely new kind of planet, an extra-large gas giant unlike any known world in our solar system or beyond. \n\n"This questions our understanding of how giant planets are formed and evolve," said Robert Noyes, a senior physicist at the Harvard-Smithsonian Center for Astrophysics (CfA). \n\n\nThe planet, dubbed HAT-P-1, is located some 450 light-years from Earth in the constellation Lacerta. \n\nIt is the largest planet ever discovered and boasts a radius nearly 1.4 times larger than Jupiter's. \n\nHAT-P-1 is also the least dense of all known planets. \n\n"This planet is about one quarter the density of water," said Gaspar Bakos, a Hubble fellow at CfA. \n\n"In other words, it's lighter than a giant ball of cork. Just like Saturn, it would float in a bathtub if you could find a tub big enough to hold it, but it would float almost three times higher." \n\nUnlike more familiar gas giants, including those in our solar system, HAT-P-1 does not appear to have a solid core.
1107840
Because there are still arguments whether Pluto is actually a planet, "Sedna" is larger than Pluto. But I believe the argument stems from sheer distance from the Sun, it is more of a rogue body.
118270
There are alot of objects that exist beyond Pluto. Yet, at this point none of these is really large enough to be considered a planet. Check the source link for more info.
584504
10 is my answer. A new planet call UB313 was discovered. Here are they planets in order:\nMecury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto.\n\n10 Planets said. 10 Points for the best answer