|
 The planet, which is about 60 percent bigger than Earth, is
located 1,400 light years away in the constellation Cygnus. It was
discovered by astronomers using NASA’s Kepler space telescope and
circles a star that is similar in size and temperature to the sun,
but older.
“In my mind, this is the closest thing we have to another planet
like the Earth,” astronomer Jon Jenkins, with the U.S. space
agency's Ames Research Center in Moffett Field, California, told
reporters on a conference call. The planet, dubbed Kepler-452b,
orbits a star that is about 6 billion years old, compared to the 4.6
billion year age of the sun. “It’s simply awe-inspiring to consider
that this planet has spent 6 billion years in the habitable zone of
its star,” Jenkins said.
“That’s considerable time and opportunity for life to arise
somewhere on its surface or in its oceans should all the necessary
ingredients and conditions for life exist on this planet,” he said.
Kepler-452b is positioned about as far from its parent star as Earth
is from the sun, completing an orbit in 385 days, compared to
Earth’s 365-day orbit. At that distance, surface temperatures would
be suitable for liquid water, a condition believed to be critical
for life. Scientists previously have found Earth-sized planets
orbiting in stars’ so-called “habitable zones,” but those stars are
cooler and smaller than the sun, a G2 type yellow star.
NASA launched the Kepler telescope in 2009 to survey a sampling of
nearby stars in an attempt to learn if planets like Earth were
common in the galaxy.
"This is great progress in finding a planet like Earth that is
similar in size and temperature around a sun-like star,” said Kepler
scientist Jeff Coughlin, with the SETI Institute in Mountain View,
California. Based on its size, scientists believe Kepler-452b should
be rocky, like the Earth, though that theory is based on statistical
analysis and computer modeling, not direct evidence.
“With a radius 60 percent larger than the Earth, this planet has a
somewhat better than even chance of being rocky,” Jenkins said.
[to top of second column] |
If so, Kepler-452b could be about five times as massive as Earth and
have gravity that is twice as strong as what exists on Earth’s
surface. The planet also could have a thick atmosphere, cloudy skies
and active volcanoes, Jenkins said.
With the discovery of Kepler-452b, the telescope has found 1,030
confirmed planets and identified about 4,700 candidate planets. The
list of potential planets includes 11 other near-Earth twins, nine
of which circle sun-like stars.
The telescope cannot see planets directly, but measures minute
changes in light coming from target stars. Sophisticated computer
programs and follow-up observations with a ground-based telescopes
then determine if some of the light dips were caused by planets
passing in front of their parent stars, relative to Kepler’s line of
sight.
A positioning system failure ended the telescope’s prime
planet-hunting mission in 2013, but it has since been repurposed for
other astronomical observations.
Attempts to learn if Kepler-452b has an atmosphere likely will have
to wait for a new generation of more sensitive space telescopes,
said NASA’s associate administrator John Grunsfeld. The research
will be published in The Astronomical Journal.
(Reporting by Irene Klotz; Editing by David Adams and Tom Brown)
[© 2015 Thomson Reuters. All rights
reserved.]
Copyright 2015 Reuters. All rights reserved. This material may not be published,
broadcast, rewritten or redistributed.
 |
