NASA Confirms "New Earth" Exists in Habitable Zone
Pack your bags everyone, it' time to go for a Christmas holiday to
the stars. Away from iPods, away from Celebrity Reality Shows, to a
place that's a little bit roomier, a little big newer - and a little
bit Earthy.
NASA has confirmed that it's Kepler mission has
discovered its first planet in the "habitable zone", the region where
liquid water could exist on a planet's surface.
Kepler also
has discovered more than 1,000 new planet candidates, nearly doubling
its previously known count. Ten of these candidates are near-Earth-size
and orbit in the habitable zone of their host star.
The newly
confirmed planet, Kepler-22b, is the smallest yet found to orbit in the
middle of the habitable zone of a star similar to our sun. The planet
is about 2.4 times the radius of Earth although scientists are yet to
confirm as to whether the planet has a predominantly rocky, gaseous or
liquid composition.
Previous research hinted at the existence of
near-Earth-size planets in habitable zones, but clear confirmation
proved elusive. Two other small planets orbiting stars smaller and
cooler than our sun recently were confirmed on the very edges of the
habitable zone, with orbits more closely resembling those of Venus and
Mars.
"This is a major milestone on the road to finding Earth's
twin" said Douglas Hudgins, Kepler program scientist at NASA
Headquarters in Washington.
Kepler discovers planets and planet
candidates by measuring dips in the brightness of more than 150,000
stars to search for planets that cross in front, or "transit", the
stars. Kepler requires at least three transits to verify a signal as a
planet.
The Kepler science team uses ground-based telescopes and
the Spitzer Space Telescope to review observations on planet candidates
the spacecraft finds. The star field that Kepler observes
in the constellations Cygnus and Lyra can only be seen from
ground-based observatories in spring through early fall. The data from
these other observations help determine which candidates can be
validated as planets.
The Kepler team is hosting its inaugural
science conference at Ames Dec. 5-9, announcing 1,094 new planet
candidate discoveries. Since the last catalog was released in February,
the number of planet candidates identified by Kepler has increased by
89 percent and now totals 2,326. Of these, 207 are
approximately Earth-size, 680 are super Earth-size, 1,181 are
Neptune-size, 203 are Jupiter-size and 55 are larger than Jupiter.
Kepler
observed many large planets in small orbits early in its mission, which
were reflected in the February data release. Having had more time to
observe three transits of planets with longer orbital periods, the new
data suggest that planets one to four times the size of Earth may be
abundant in the galaxy.
There are 48 planet candidates in their
star's habitable zone, with the Kepler team applying a stricter
definition of what constitutes a habitable zone to account for the
warming effect of atmospheres, which would move the zone away from the
star, out to longer orbital periods.
"The tremendous growth in
the number of Earth-size candidates tells us that we're honing in on
the planets Kepler was designed to detect : those that are not only
Earth-size, but also are potentially habitable," said Natalie Batalha,
Kepler deputy science team lead at San Jose State University. "The more data we collect, the keener our eye for finding the smallest planets out at longer orbital periods."
So keep your eyes on the skies! |
