NASA FINDS EARTH-SIZE PLANET
CANDIDATES IN HABITABLE ZONE, SIX PLANET SYSTEM
From NASA
Feb. 02, 2011
Candidates require follow-up
observations to verify they are actual planets. Kepler also found
six confirmed planets orbiting a sun-like star, Kepler-11. This is the
largest group of transiting planets orbiting a single star yet
discovered outside our solar system. "In one generation we have gone from
extraterrestrial planets being a mainstay of science fiction, to the present,
where Kepler has helped turn science fiction into today's reality," said
NASA Administrator Charles Bolden. "These discoveries underscore the
importance of NASA's science missions, which consistently increase
understanding of our place in the cosmos."
The discoveries are part of
several hundred new planet candidates identified in new Kepler
mission science data, released on Tuesday, Feb. 1. The findings increase the
number of planet candidates identified by Kepler to-date to 1,235. Of these, 68
are approximately Earth-size; 288 are
super-Earth-size; 662 are Neptune-size; 165 are the size of Jupiter and 19 are
larger than Jupiter. Of the 54 new planet candidates found in the habitable
zone, five are near Earth-sized. The remaining 49 habitable zone candidates
range from super-Earth size -- up to twice the size of Earth -- to larger than
Jupiter. The findings are based on the results of observations conducted May 12
to Sept. 17, 2009, of more than 156,000 stars in Kepler's field of view, which
covers approximately 1/400 of the sky.
"The fact that we've
found so many planet candidates in such a tiny fraction of the sky suggests
there are countless planets orbiting sun-like stars in our
galaxy," said William Borucki of NASA's Ames Research Center
in Moffett Field , Calif. , the mission's science principal investigator.
"We went from zero to 68 Earth-sized planet candidates and zero to 54
candidates in the habitable zone, some of which could have moons with
liquid water." Among the stars with planetary candidates, 170 show
evidence of multiple planetary candidates. Kepler-11, located approximately
2,000 light years from Earth, is the most tightly packed planetary system yet
discovered. All six of its confirmed planets have orbits smaller than Venus,
and five of the six have orbits smaller than Mercury's. The only other star
with more than one confirmed transiting planet is Kepler-9, which has three.
The Kepler-11 findings will be published in the Feb. 3 issue of the journal
Nature.
"Kepler-11 is a
remarkable system whose architecture and dynamics provide clues about its
formation," said Jack Lissauer, a planetary scientist and Kepler science
team member at Ames .
"These six planets are mixtures of rock and gases,
possibly including water. The rocky material accounts for most
of the planets' mass, while the gas takes up most of their volume. By
measuring the sizes and masses of the five inner planets, we
determined they are among the lowest mass
confirmed planets beyond our
solar system." All of the planets orbiting Kepler-11 are larger than
Earth, with the largest ones being comparable in size to Uranus and Neptune.
The innermost planet, Kepler-11b, is ten times closer to its star than Earth is
to the sun. Moving outward, the other planets are Kepler-11c, Kepler-11d,
Kepler-11e, Kepler-11f, and the outermost planet, Kepler-11g, which is half as
far from its star as Earth is from the sun.
The planets Kepler-11d,
Kepler-11e and Kepler-11f have a significant amount of light gas, which
indicates that they formed within a few million years of the
system's formation. "The historic milestones Kepler makes with each new
discovery will determine the course of every exoplanet mission to follow,"
said Douglas Hudgins, Kepler program scientist at NASA Headquarters in Washington .
Kepler, a space telescope,
looks for planet signatures by measuring tiny decreases in the
brightness of stars caused by planets crossing in front of them. This is
known as a transit. Since transits of planets in the habitable zone of sun-like
stars occur about once a year and require three transits for verification, it
is expected to take three years to locate and verify Earth-size planets
orbiting sun-like stars.
[Slightly old news I know
but worth repeating (or bringing to your attention if you missed it). The
discovery of Earth-like planets in habitable zones in star systems very much
like our own gives great (if admittedly circumstantial) credence to the idea
that life – even intelligent life – could very possibly exist on other worlds
orbiting other stars. Those who continually dismiss even the possibility of
life elsewhere need to contend with the growing number of planetary discoveries
orbiting stars not too dissimilar to our own and in just the place they need to
be to allow liquid water to exist on their surface. If, like me, you believe
that life emerged on Earth as part of a natural process without the need for
supernatural agency you cannot but agree that if it can happen here in the
right circumstances then it can happen elsewhere too if those circumstances are
similar enough. The odd, it increasingly appears, are being stacked in favour
of finding life elsewhere in our galaxy. Now all we need to do is actually go
and find it.]
2 comments:
Those who dismiss the possibility of life elsewhere are pursuing a religious agenda and have no grasp of astronomical numbers. Make the odds against life as steep as you want; the sheer number of chances will still dictate that life elsewhere is almost a certainty.
And intelligent life? Well, there's hardly a more exciting prospect to contemplate. And the waiting and the search makes the question almost impossibly alluring.
If only we could get some *hard* evidence. I'd be so happy...... [grin]
I must definitely do the promised 'Thinking About' post on this subject.....
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