Search for Another Earth Quietly Underway
- Search for Another Earth Quietly Underway
By Robert Roy Britt
Space.com Senior Science Writer
After a five-year search that has turned up more than 40 giant, inhospitable
planets around other stars, the hunt is quietly underway to discover another
place like home. And while no scientist can say for sure that any such
planet exists, optimism is high that another Earth will be found within the
decade, possibly much sooner. Several space missions have been dreamed up to
search for Earth-like planets around other stars. Some may remain dreams,
others are closer to reality. We detail six of the more promising
It would be adiscovery of sizeable historic proportion, akin to learning
that our solar system was not the center of the universe and recharging the
growing expectation that we are not alone.
And it could galvanize and accelerate efforts to explore space to a degree
not seen since the U.S.-Sovietspace race.
The sheer volume and variety of extrasolar planets found so far fuels a
strong expectation among those involved in the search that there must be
other Earth-sized planets orbiting other stars at distances suitable for
"There are about 200 billion stars in our galaxy," said Paul Butler of the
Carnegie Institution of Washington. "I would guess that Earth-like planets
Butler and a colleague, Geoffrey Marcy, pioneered the hunt for extrasolar
planets, or exoplanets. They lead teams that detect small wobbles in stars
caused by the gravitational pull of an orbiting planet. Along with their
colleagues, they have found the majority of confirmed other worlds.
But the wobble method so far spots mostly very large planets that orbit
extremely close to their host stars -- many are closer than Mercury is to
our Sun-- not a place you'd want to live. And scientists have yet to see
these planets directly.
Now, new methods and a handful of missions on the horizon are close to
bringing another Earth within our optical reach.
Earth-sized planet discovery imminent
In recent interviews, three leading planet hunters told SPACE.com that a
potentially habitable Earth-like planet might well be found within 10 years.
And extrasolar planets in the "terrestrial" range -- no more than 2.5 times
the size of Earth -- could be found within five years, possibly even during
Discovering one of these so-called "terrestrials" could well spur the
funding, decisions and brainstorming needed to support missions that would
root out truly habitable planets, scientists say.
Uplink Your Views
Will we find another Earth? How long will it take?
Hans J. Deeg, a planet hunter involved in multiple searches, says if either
of two planned missions gets off the drawing boards in a timely manner --
the ESA's Eddington mission or NASA's Kepler mission -- then a truly
Earth-sized planet should be found in about 10 years.
Meanwhile, Deeg is currently working on COROT, a European space-based
telescope due to launch in 2004.
"The COROT mission should find planets about twice Earth's diameter within
five years -- if they exist," Deeg said.