Earthlike Exoplanet Found
In this, one of the few, if not the only Michael Jackson-free blog on these Internets, I give you a story about the discovery of what is thus far the most Earthlike exoplanet, in terms of mass, orbiting one of our closest stellar neighbors, a red dwarf called Gliese 876. The following excerpt from Sky and Telescope gives more details:
June 13, 2005 After three years of maintaining secrecy while collecting more and more evidence, a team of astronomers today announced finding an entirely new type of planet orbiting a dim star 15 light-years away. The object is the lightest known extrasolar planet orbiting a normal star, with a mass between 6 and 9 Earths and most likely 7½ Earth masses. At a National Science Foundation press conference this afternoon, Geoffrey W. Marcy (University of California, Berkeley), R. Paul Butler (Carnegie Institution of Washington), and four colleagues called their find the most Earthlike world yet discovered outside our solar system.
While that is technically true, the planet is truly weird by any Earthly standard. The new world orbits the red-dwarf star Gliese 876 at a distance of only 2 million miles (3.2 million kilometers, or 0.021 astronomical unit) with an orbital period — a "year" — that is only 46 hours long. It's so close to its little star that the star must appear in its sky as a fireball 12° across — some 24 times as wide as the Sun in Earth's sky, or about the size of a tennis ball held at arm's length.
As a result, the planet's temperature should be some 200° to 400° Celsius (400° to 750° Fahrenheit), well above the boiling point of water at Earth's atmospheric pressure but perhaps below the boiling point of water if the world has a thick enough atmosphere, barring a strong greenhouse effect. Whether it has an atmosphere at all is unknown. It could consist of bare rock, rock swathed in an atmosphere as thick as Earth's or Venus's, or it could be a Uranus analog, a hot "ice giant" in which a massive atmosphere rich in cosmic volatiles (water, methane, ammonia) comprises a fair fraction of the objects' entire bulk. If the world is rocky it would be a little less than twice Earth's diameter in size, and its strong surface gravity would probably keep its topography relatively flat.
Full story: http://skyandtelescope.com/news/article_1530_1.asp
Of course, given the information described in the excerpt, this planet is almost certainly uninhabitable, but the point that planets smaller than the gas giants that have been found, some of which are five to ten times more massive than Jupiter, the largest planet in our solar system, exist and are right in our own back yard, in a manner of speaking.
I don't want to get too political here because this is a HUGE story. It is much bigger than any celebrity trial, sporting event or any of the other fifteen disposable headlines the major networks pass off as "news". This story really IS news. It is news because it is something that is completely unexpected and unseen in our time. The only way this story could be bigger is if we could somehow detect the presence of life on this world. Maybe then we would start to see reporters re-discover the skills they lost when they decided to become purveyors of fluff or mouthpieces of the Bush administration. Maybe. But then again maybe not because when Paris Hilton does her Latest Stupid Thing of the Week, these idiots will trip all over themselves once again to see who can be the first to type it up.
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