The coolest exoplanets

You may not realize it from reading the news, but so many extrasolar planets are being discovered now that most aren't even reported. Sure, we all heard about Gliese 581 C, the planet 120 trillion miles from Earth which is the most "Earth-like" body yet discovered. But since then the trickle of discoveries has turned into a flood, and the news just can't keep up. So for those of you who don't bury your heads in scientific periodicals, here are some of most interesting new planets on the block:

"¢ Upsilon Andromeda b is tidally locked to its sun like Earth is to its moon, which means that one side is always facing the sun and the other away from it. As such, it has such extreme surface temperature variations that one side of it is like the deepest part of a volcano on Earth, and the other side often below freezing.

"¢ TrES-3 is about twice the size of Jupiter, 50 times closer to its sun than Earth, and zips through its full orbit in only 31 hours, giving it a 1.3-day year. It's fast, hot and out of control!

"¢ The longest orbit, on the other hand, is that of HD 154345 b, which takes 13,100 days to complete one transit around its star.

"¢ The oldest planet is 12.7 billion years, meaning it was formed just two billion years after the Big Bang. It raises the prospect of life existing in the universe far earlier than scientists had imagined.

"¢ A year on HD209458b is only 3.5 Earth-days long. The planet orbits so close to its star that its atmosphere is being blown away by gales of stellar wind. Scientists estimate the planet is losing at least 10,000 tons of material every second. Eventually, only a dead core of the shrinking planet will remain.