A reason to stay up

At the Christian Science Monitor, scientists are using tonight's eclipse to get a better idea of how light from an earthlike planet (like Earth!) would look to spectrum analysts (like us!). 
Lunar eclipse tonight: How it helps the search for extraterrestrial life
Over the past two years, two teams of astronomers have been using this effect to figure out what Earth might look like as a distant, extrasolar planet orbiting another star. By analyzing the light reflected off the moon during a lunar eclipse – light that has passed through Earth's atmosphere – they have detected gases in the atmosphere that indicate the presence of organic life on the planet.
If the teams' baby steps are any indication, the techniques they are developing may be able to detect evidence of organic life imprinted in an extrasolar planet's atmosphere – at least for rocky, Earth-mass planets orbiting stars relatively close to the sun – using large Earthbound telescopes.
"It's an exciting experiment – one of the few I've seen that I wish I'd thought of myself," says Sara Seager [well lah dee dah! -J], a physicist at the Massachusetts Institute of Technology who studies exoplanets and their atmospheres and who was not involved in either project.
"The Earth is our best laboratory; it's the only planet we know of with life," she says. "So we really want to understand what Earth would look like as an exoplanet far away."
Less seriously, I'd also like to point another possibility that served as a premise of a recent Iain Banks novel: Aliens might come to earth to see the eclipse. 

One of earth's unusual features (we think) is the relative size of and distance to our moon. It is astronomically unlikely to have a huge moon perfectly positioned so that it has the same apparent size in the two-dimensional sky. Other planets don't have moons that can create total solar eclipses, where the corona of the sun shines around the edge of the moon.

So if there were any reason for aliens to come to earth (and let's face it, they aren't interested in Dancing with the Stars) would be to see such an unusual natural wonder. 

Although this is just a lunar eclipse, it's still a sight. So look around. If you see some not-quite-right-looking folks staring at the sky, introduce yourself. You might make some new alien friends. 


  1. Which Iain Banks novel is this? A great idea!

  2. It is 2009's "Transition". Not Banks's best work, but not his worst, either.


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