Planets Found Circling Other Stars: 429 So Far

"Out There: A Strange Zoo of Other Worlds"
Space.com (February 14, 2010)

"More than 400 worlds have been found beyond the reach of our sun, and the tally is rising rapidly. From super-Earths to giants dwarfing Jupiter, our galaxy is a zoo of different kinds of planets.

"Hot Jupiters

"The first discovery of an extrasolar planet around a sun-like star was 51 Pegasi B, an exoplanet roughly 50 light-years away, unofficially named Bellerophon after the tamer of the mythical Pegasus.

"Like many alien worlds found after it, 51 Pegasi B was a 'hot Jupiter,' a gas giant as close or closer to its star than Mercury is to our sun, unlike 'cold Jupiters' that orbit farther away such as Saturn or, naturally, Jupiter.

"Of the 429 exoplanets discovered to date, 89 have been hot Jupiters, likely because their large size and proximity to their stars makes them easier to spot by current techniques.

"Pulsar planets...."

Those aren't pulsars that are planets, but planets orbiting pulsars. They're pretty close to the 'there ain't no such animal' variety of observed phenomena.

Then there are

• Super-Earths
• Hot Neptunes
• Water worlds
• Chthonian planets
• Free-floating planets

Quoted in another blog:

"Not only is the universe stranger than we imagine, it is stranger than we can imagine."
Sir Arthur Eddington English astronomer (1882 - 1944)
(Drifting at the Edge of Time and Space (November 1, 2009)

The Space.com article is a pretty good overview of the sorts of planets we've found to date outside the Solar system: and ends with this:

"...An obvious hope is to find a Goldilocks planet just right for life — a planet at the right distance from its star to not roast or freeze and just the right size to retain an atmosphere but not so large as to become a gas giant. 'We're on a quest with a very high probability of success of finding a planet that's habitable or even inhabited with primitive life around other stars,' Beichman said. 'As we're progressing on that path, every time we round the bend along the way, we're finding fantastic new vistas.' "

Or not-so-primitive life.

The "Goldilocks Planet" May Not Be Like Earth

An intriguing possibility is that Earth isn't a "Goldilocks planet." What we've discovered about Mars and Venus suggest that our Earth may be about as small as a planet can be, and still have conditions that allow life. (December 5, 2009) We'll know more, when we've done a more thorough survey of this part of the Milky Way galaxy.

Related posts:

• "Second Smallest Exoplanet Found: HD 156668b (Caution! Geeky Content!)"
  (January 10, 2010)
• "Well, That's Interesting: The Evolution of Galaxies"
  Drifting at the Edge of Time and Space (February 8, 2010)
• "Probable Super-Earths Found: One Nearby"
  (December 14, 2009)
• "Earth May Not Be a 'Class M' Planet"
  (December 5, 2009)
• "Gliese 581: Lightest Known Expoplanet (Caution! Geeky Content!)"
  (April 21, 2009)

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Related posts, at

• "A Serious Search for Other Worlds, Life, and - Maybe - Extra-Terrestrial Intelligence"