Alpha Centauri B: New Planet

"Earth-Size Planet Closest to Our Solar System: By The Numbers"
Tariq Malik, SPACE.com (October 17, 2012)

"An alien planet discovered around a star in the Alpha Centauri system, the nearest to our own sun, has astronomers buzzing, and not just because it's the closest exoplanet to Earth ever seen.

"The newfound extrasolar planet Alpha Centauri Bb, it turns out, is not only the nearest alien world to Earth, it's also extremely Earthlike in size and mass. The planet is much too hot and too close to its parent star to support life, but its existence suggests the tantalizing possibility that there may be more planets waiting to be found in our neighboring star system.

"Here's a look at the numbers behind the newfound alien planet Alpha Centauri Bb:...

"3.6 million: The distance, in miles, at which the planet orbits its parent star Alpha Centauri B. This is much closer to the star than Mercury is to our sun. Earth is 93 million miles (150 million km) from the sun...."

Astronomers have found hundreds of exoplanets: planets orbiting other stars. What makes Alpha Centauri Bb stand out is it's mass, very nearly the same as Earth; and that it's very close.

"Close," that is, compared to most stars. Alpha Centauri A, B, and C are the nearest (known) stars: only four and a quarter light years away.

That's almost in Earth's back yard, compared to the size of our galaxy. Even Gliese 581, 20 light years away, is a close neighbor on a galactic scale.


(from Department of Physics, University of Oregon, used w/o permission)

On this scale, each pixel is well over 100 light years across. Sun and Gliese 581 are in the same pixel.

Too Hot for Life?

Alpha Centuari Bb "is much too hot and too close to its parent star to support life" is accurate, as far as it goes. The statement assumes that "life" is limited to "life as we know it," the sort of nucleic acid/protein (O) in water variety here on Earth. Maybe that's the only kind anywhere.

Then again, maybe "life" doesn't need to be the nucleic acid/protein in water mix that's comfortable on Earth. Life using fluorosilicone in fluorosilicone instead of our organic mix might be right at home on a nearly red-hot world.

Or maybe critters made of lipid in hydrogen live in the borderlands of our own planetary system. (Drifting at the Edge of Time and Space (April 12, 2010)

Alpha Centauri Bb: Really?

Some announcements of exoplanets are disputed, and occasionally turn out to be a misinterpretation of noise in the data. This time, it looks like Alpha Centauri Bb is very real: but time will tell.

• Exoplanets
  • "GJ 667Cc: Heavier than Earth, Maybe About as Warm"
    (February 6, 2012)
  • "Exoplanets: Over 700 Found to Date; Latest Batch of 18 are Jupiter-Size"
    (December 5, 2011)
  • "Gliese 581d: Rocky, Close (sort of), and Liquid Water (could be, maybe)"
    (May 18, 2011)
  • "GJ 1214b: Water in the Atmosphere; Close; and No Vacation Destination"
    (February 23, 2011)
  • "Gliese 581g, Alien Angst, and the Lemming"
    (October 4, 2010)
• Space aliens
  • "Alien Life will Most Likely be - Alien"
    Drifting at the Edge of Time and Space (April 12, 2010)
  • "Nuclear Weapons, Space Aliens, Conspiracy Theories, and Getting a Grip"
    (September 24, 2010)
  • "Gliese 581g, Space Aliens, and the Canals of Mars"
    (October 12, 2010)
  • "Space Aliens, the News, and Those Catholics"
    (November 11, 2009)
  • "Timing is Everything"
    Drifting at the Edge of Time and Space (October 7, 2009)