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Earth-Like Planet Discovered Orbiting Nearby Star
Wednesday, April 25, 2007
WASHINGTON - For the first time astronomers have discovered a planet
outside our solar system that is potentially habitable, with Earth-like
temperatures, a find researchers described Tuesday as a big step in the
search for "life in the universe."
The planet is just the right size, might have water in liquid form, and in
galactic terms is relatively nearby at 120 trillion miles away. But the star
it closely orbits, known as a "red dwarf," is much smaller, dimmer and
cooler than our sun.
There's still a lot that is unknown about the new planet, which could be
deemed inhospitable to life once more is known about it. And it's worth
noting that scientists' requirements for habitability count Mars in that
category: a size relatively similar to Earth's with temperatures that would
permit liquid water. However, this is the first outside our solar system
that meets those standards.
"It's a significant step on the way to finding possible life in the
universe," said University of Geneva astronomer Michel Mayor, one of 11
European scientists on the team that found the planet. "It's a nice
discovery. We still have a lot of questions."
The results of the discovery have not been published but have been submitted
to the journal Astronomy and Astrophysics.
Alan Boss, who works at the Carnegie Institution of Washington where a U.S.
team of astronomers competed in the hunt for an Earth-like planet, called it
"a major milestone in this business."
The planet was discovered by the European Southern Observatory's telescope
in La Silla, Chile, which has a special instrument that splits light to find
wobbles in different wave lengths. Those wobbles can reveal the existence of
other worlds.
What they revealed is a planet circling the red dwarf star, Gliese 581. Red
dwarfs are low-energy, tiny stars that give off dim red light and last
longer than stars like our sun. Until a few years ago, astronomers didn't
consider these stars as possible hosts of planets that might sustain life.
The discovery of the new planet, named 581 c, is sure to fuel studies of
planets circling similar dim stars. About 80 percent of the stars near Earth
are red dwarfs.
The new planet is about five times heavier than Earth. Its discoverers
aren't certain if it is rocky like Earth or if its a frozen ice ball with
liquid water on the surface. If it is rocky like Earth, which is what the
prevailing theory proposes, it has a diameter about 1 1/2 times bigger than
our planet. If it is an iceball, as Mayor suggests, it would be even bigger.
Based on theory, 581 c should have an atmosphere, but what's in that
atmosphere is still a mystery and if it's too thick that could make the
planet's surface temperature too hot, Mayor said.
However, the research team believes the average temperature to be somewhere
between 32 and 104 degrees and that set off celebrations among astronomers.
Until now, all 220 planets astronomers have found outside our solar system
have had the "Goldilocks problem." They've been too hot, too cold or just
plain too big and gaseous, like uninhabitable Jupiter.
The new planet seems just right - or at least that's what scientists think.
"This could be very important," said NASA astrobiology expert Chris McKay,
who was not part of the discovery team. "It doesn't mean there is life, but
it means it's an Earth-like planet in terms of potential habitability."
Eventually astronomers will rack up discoveries of dozens, maybe even
hundreds of planets considered habitable, the astronomers said. But this
one - simply called "c" by its discoverers when they talk among themselves -
will go down in cosmic history as No. 1.
Besides having the right temperature, the new planet is probably full of
liquid water, hypothesizes Stephane Udry, the discovery team's lead author
and another Geneva astronomer. But that is based on theory about how planets
form, not on any evidence, he said.
"Liquid water is critical to life as we know it," co-author Xavier Delfosse
of Grenoble University in France, said in a statement. "Because of its
temperature and relative proximity, this planet will most probably be a very
important target of the future space missions dedicated to the search for
extraterrestrial life. On the treasure map of the Universe, one would be
tempted to mark this planet with an X."
Other astronomers cautioned it's too early to tell whether there is water.
"You need more work to say it's got water or it doesn't have water," said
retired NASA astronomer Steve Maran, press officer for the American
Astronomical Society. "You wouldn't send a crew there assuming that when you
get there, they'll have enough water to get back."
The new planet's star system is a mere 20.5 light years away, making Gliese
581 one of the 100 closest stars to Earth. It's so dim, you can't see it
without a telescope, but it's somewhere in the constellation Libra, which is
low in the southeastern sky during the midevening in the Northern
Hemisphere.
"I expect there will be planets like Earth, but whether they have life is
another question," said renowned astrophysicist Stephen Hawking in an
interview with The Associated Press in Orlando. "We haven't been visited by
little green men yet."
Before you book your extrastellar flight to 581 c, a few caveats about how
alien that world probably is: Anyone sitting on the planet would get heavier
quickly, and birthdays would add up fast since it orbits its star every 13
days.
Gravity is 1.6 times as strong as Earth's so a 150-pound person would feel
like 240 pounds.
But oh, the view. The planet is 14 times closer to the star it orbits. Udry
figures the red dwarf star would hang in the sky at a size 20 times larger
than our moon. And it's likely, but still not known, that the planet doesn't
rotate, so one side would always be sunlit and the other dark.
Distance is another problem. "We don't know how to get to those places in a
human lifetime," Maran said.
Two teams of astronomers, one in Europe and one in the United States, have
been racing to be the first to find a planet like 581 c outside the solar
system.
The European team looked at 100 different stars using a tool called HARPS
(High Accuracy Radial Velocity for Planetary Searcher) to find this one
planet, said Xavier Bonfils of the Lisbon Observatory, one of the
co-discoverers.
Much of the effort to find Earth-like planets has focused on stars like our
sun with the challenge being to find a planet the right distance from the
star it orbits. About 90 percent of the time, the European telescope focused
its search more on sun-like stars, Udry said.
A few weeks before the European discovery earlier this month, a scientific
paper in the journal Astrobiology theorized a few days that red dwarf stars
were good candidates.
"Now we have the possibility to find many more," Bonfils said.
Earth-Like Planet Discovered Orbiting Nearby Star
Wednesday, April 25, 2007
WASHINGTON - For the first time astronomers have discovered a planet
outside our solar system that is potentially habitable, with Earth-like
temperatures, a find researchers described Tuesday as a big step in the
search for "life in the universe."
The planet is just the right size, might have water in liquid form, and in
galactic terms is relatively nearby at 120 trillion miles away. But the star
it closely orbits, known as a "red dwarf," is much smaller, dimmer and
cooler than our sun.
There's still a lot that is unknown about the new planet, which could be
deemed inhospitable to life once more is known about it. And it's worth
noting that scientists' requirements for habitability count Mars in that
category: a size relatively similar to Earth's with temperatures that would
permit liquid water. However, this is the first outside our solar system
that meets those standards.
"It's a significant step on the way to finding possible life in the
universe," said University of Geneva astronomer Michel Mayor, one of 11
European scientists on the team that found the planet. "It's a nice
discovery. We still have a lot of questions."
The results of the discovery have not been published but have been submitted
to the journal Astronomy and Astrophysics.
Alan Boss, who works at the Carnegie Institution of Washington where a U.S.
team of astronomers competed in the hunt for an Earth-like planet, called it
"a major milestone in this business."
The planet was discovered by the European Southern Observatory's telescope
in La Silla, Chile, which has a special instrument that splits light to find
wobbles in different wave lengths. Those wobbles can reveal the existence of
other worlds.
What they revealed is a planet circling the red dwarf star, Gliese 581. Red
dwarfs are low-energy, tiny stars that give off dim red light and last
longer than stars like our sun. Until a few years ago, astronomers didn't
consider these stars as possible hosts of planets that might sustain life.
The discovery of the new planet, named 581 c, is sure to fuel studies of
planets circling similar dim stars. About 80 percent of the stars near Earth
are red dwarfs.
The new planet is about five times heavier than Earth. Its discoverers
aren't certain if it is rocky like Earth or if its a frozen ice ball with
liquid water on the surface. If it is rocky like Earth, which is what the
prevailing theory proposes, it has a diameter about 1 1/2 times bigger than
our planet. If it is an iceball, as Mayor suggests, it would be even bigger.
Based on theory, 581 c should have an atmosphere, but what's in that
atmosphere is still a mystery and if it's too thick that could make the
planet's surface temperature too hot, Mayor said.
However, the research team believes the average temperature to be somewhere
between 32 and 104 degrees and that set off celebrations among astronomers.
Until now, all 220 planets astronomers have found outside our solar system
have had the "Goldilocks problem." They've been too hot, too cold or just
plain too big and gaseous, like uninhabitable Jupiter.
The new planet seems just right - or at least that's what scientists think.
"This could be very important," said NASA astrobiology expert Chris McKay,
who was not part of the discovery team. "It doesn't mean there is life, but
it means it's an Earth-like planet in terms of potential habitability."
Eventually astronomers will rack up discoveries of dozens, maybe even
hundreds of planets considered habitable, the astronomers said. But this
one - simply called "c" by its discoverers when they talk among themselves -
will go down in cosmic history as No. 1.
Besides having the right temperature, the new planet is probably full of
liquid water, hypothesizes Stephane Udry, the discovery team's lead author
and another Geneva astronomer. But that is based on theory about how planets
form, not on any evidence, he said.
"Liquid water is critical to life as we know it," co-author Xavier Delfosse
of Grenoble University in France, said in a statement. "Because of its
temperature and relative proximity, this planet will most probably be a very
important target of the future space missions dedicated to the search for
extraterrestrial life. On the treasure map of the Universe, one would be
tempted to mark this planet with an X."
Other astronomers cautioned it's too early to tell whether there is water.
"You need more work to say it's got water or it doesn't have water," said
retired NASA astronomer Steve Maran, press officer for the American
Astronomical Society. "You wouldn't send a crew there assuming that when you
get there, they'll have enough water to get back."
The new planet's star system is a mere 20.5 light years away, making Gliese
581 one of the 100 closest stars to Earth. It's so dim, you can't see it
without a telescope, but it's somewhere in the constellation Libra, which is
low in the southeastern sky during the midevening in the Northern
Hemisphere.
"I expect there will be planets like Earth, but whether they have life is
another question," said renowned astrophysicist Stephen Hawking in an
interview with The Associated Press in Orlando. "We haven't been visited by
little green men yet."
Before you book your extrastellar flight to 581 c, a few caveats about how
alien that world probably is: Anyone sitting on the planet would get heavier
quickly, and birthdays would add up fast since it orbits its star every 13
days.
Gravity is 1.6 times as strong as Earth's so a 150-pound person would feel
like 240 pounds.
But oh, the view. The planet is 14 times closer to the star it orbits. Udry
figures the red dwarf star would hang in the sky at a size 20 times larger
than our moon. And it's likely, but still not known, that the planet doesn't
rotate, so one side would always be sunlit and the other dark.
Distance is another problem. "We don't know how to get to those places in a
human lifetime," Maran said.
Two teams of astronomers, one in Europe and one in the United States, have
been racing to be the first to find a planet like 581 c outside the solar
system.
The European team looked at 100 different stars using a tool called HARPS
(High Accuracy Radial Velocity for Planetary Searcher) to find this one
planet, said Xavier Bonfils of the Lisbon Observatory, one of the
co-discoverers.
Much of the effort to find Earth-like planets has focused on stars like our
sun with the challenge being to find a planet the right distance from the
star it orbits. About 90 percent of the time, the European telescope focused
its search more on sun-like stars, Udry said.
A few weeks before the European discovery earlier this month, a scientific
paper in the journal Astrobiology theorized a few days that red dwarf stars
were good candidates.
"Now we have the possibility to find many more," Bonfils said.