Is our world unique? Is it the only one in existence, or are there others – perhaps many others – out there? Do other beings – maybe even intelligent ones – call these worlds their home, and live out their lives completely unbeknownst to us?
It was only in 1995 that we first discovered evidence that other stars had planets, as ours does. Now we have detected many thousands of other worlds, and evidence suggests that a majority of sun-like stars possess them. Most of these stellar systems bear little resemblance to ours. The easiest planets to detect are massive worlds located close to their stars, so "hot Jupiters" dominate the current list of exoplanets. As our surveys continue, however, we are discovering more and more Neptunes and even super-Earths, in orbits farther and farther from their suns.
In the first full day of the annual meeting of the Division of Planetary Sciences of the American Astronomical Society, I listened to scientific sessions on icy worlds and on an exoplanet in a four-star system.
Do planets circle our closest stellar neighbors, the system loved by science fiction: Alpha Centauri? We don’t know. But, Debra Fischer, Julien Spronck, and their colleagues at Yale University, in part with Planetary Society support, are trying to find out.
Someone on Twitter pointed me to a paper recently posted to ArXiv titled "Evidence for 9 planets in the HD 10180 system." If the (tentative) conclusion holds up, HD 10180 will be the first exoplanetary system known to have more planets than our own.
A large team of researchers has announced in a Nature article the discovery of not one, but two, Earth-sized planets orbiting a star named Kepler-20. This article separates the observational facts from the quite-likely-to-be-true inferences from the downstream speculations.
Some parallels exist between Odysseus' journey and the discoveries of exoplanets. What initially started out as a well-planned trip from Troy back to Ithaca, turned into a series of rather unfortunate events, with episodes of fighting Cyclops and having your crew turned into swine.