MANY SCIENTISTS think that we do not have the entire universe to ourselves. It is likely, they believe, that life could have emerged, evolved, and flourished on at least some of the billions of exoplanets thought to dwell in the Milky Way alone--just as it did on our own planet. The profound question of whether or not we are alone in the universe is one that may be answered by scientific observations soon.
A panel of scientists and their affiliated institutions addressed this question at a July public panel discussion held at NASA Headquarters in Washington, D.C. The researchers outlined NASA's new road map to hunt for life elsewhere in the universe--an ongoing quest that involves a number of telescopes being used today, or else scheduled to be put into use before long.
"Sometime in the near future, people will be able to point to a star and say, 'That star has a planet like Earth.' Astronomers think it is very likely that every single star in our Milky Way galaxy has at least one planet," says Sara Seager, professor of planetary science and physics at the Massachusetts Institute of Technology.
NASA's triumphant hunt for planetary systems around stars beyond the sun began with ground-based observatories before moving to space-based technologies such as the Hubble, Spitzer, and Kepler space telescopes. The telescopes used today can gaze at a large number of stars and determine if they have one of more orbiting planets. Of even greater importance, today's telescopes can evaluate whether or not the planets are situated at the right distance from their parent stars to have liquid water--an important ingredient that enables life as we know it to evolve.
Indeed, the holy grail of planet-hunting astronomers is the discovery of an exoplanet circling a star beyond our sun that is small, rocky, and covered with churning, frothing oceans of liquid water, like our own lovely "little blue dot" lost in the vastness of space. Where liquid water exists, there is the possibility--though not the promise--for life to exist as well. We do not know as yet whether planets like Earth and beings similar to us are, in fact, common or rare throughout the universe--although many scientists now suspect that life is quite abundant.
Exoplanets are the distant offspring of a star beyond our sun, a brown dwarf, or a stellar corpse. Brown dwarfs are "failed stars," relatively lightweight substellar objects that commonly are thought to be born like stars--within a dense...