Discoveries on Extrasolar Planets
On April 21, 1994, astronomer Alexander Wolszczan discovered the first extrasolar planets, or planets located outside the solar system. Since that time, scientists have discovered at least 529 of these planets, which are also called exoplanets and have started to discover the gases that comprise their atmospheres.
On a very hot, Jupiter-like planet orbiting a star 65 light years away, scientists have discovered methane—the only molecule besides water ever to be discerned on an extrasolar planet.
A single spectral absorption band in the near infrared, recorded by NASA’s Hubble Space Telescope, indicates a modest 50 parts per million of methane in the atmosphere of the planet HD 189733b. Hubble data also confirm a previous discovery of water vapor there. In a testament to its sensitivity, Hubble’s near-IR camera measured the planetary atmosphere’s faint absorption of starlight as the planet passed in front of a star (Nature 2008, 452, 329).
“It is amazing we can detect molecules at all in the atmosphere,” Sara Seager, a Carnegie Institution of Washington astronomer unaffiliated with the research team, said at a press conference announcing the results. “This is a big breakthrough,” she said, noting that the astronomy community is “cautiously optimistic that the methane detection is robust.”
Although organisms may produce methane in abundance, astronomers stress that life as we know it could never exist on this planet, which closely orbits its star and has an atmospheric temperature that likely hovers around 1,000 K.
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Excerpted with permission, Chemical & Engineering News
Copyright © 2008 American Chemical Society