Hubble see’s first “sunset” on a distant planet
Not much pick up this week for what is, all in all, rather an interesting astronomy story. An international team using the Hubble Space Telescope examined a distant star around which a big planet already has been known to lie in an eclipsing orbit. It goes right across the star’s face. With exquisite care the astronomers were able to isolate the backlit spectrum of the planet’s atmosphere. If you were close enough to see it, it would be a hazy red outline of the planet where star light skims on past — exactly what makes a sunset’s atmospheric colors on Earth (or, for that matter, a sunrise.)
Robert S. Boyd at McClatchey’s Washington Bureau has it, and properly says that Hubble caught “what looks like a sunset.” The spectrum includes hints of iron, silicate, and aluminum oxide. The hed itself flatly calls it a sunset.
It also came out from Space.com’s Dave Mosher and also with the sunset angle.
Okay, just raising a hand with a skeptical question here (and if I get a reply from a planet-hunter with an answer I’ll let you know), but is that really a sunset? Intuition suggests that this planet, very close to its star, might be in tidal lock. If so it holds one face to the star the way the Moon keeps one side toward Earth. If a sun just sits there from its planet’s vantage, said sun neither sets nor rises. Hmmm. Just wondering.
UPDATE: Über-exoplanet-finder Geoff Marcy reports back that, indeed, such planets including this one are in tidal lock. Thus, it is correct, if a tad pedantic, that they have no sunset or sunrises.
Grist for the Mill: NASA-ESA-Hubble Press Release says sunset, too. An angle in the release worth a note: as the planet transited, variations in the star’s overall brightness hint that it crossed over some big sunspots.
Pic: artist’s impression, hi res
-CP
This entry was posted on Friday, December 14th, 2007 at 3:44 pm and is filed under Science Stories. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
