WASHINGTON:
European astronomers say that just outside our solar system they’ve
found a planet that’s the closest you can get to Earth in location and
size.
It is the type of planet they’ve been searching
for across the Milky Way galaxy and they found it circling a star right
next door — 25 trillion miles (40 trillion kilometres) away. But the
Earth-like planet is so hot its surface may be like molten lava. Life
cannot survive the 2,200 degree heat of the planet, so close to its star
that it circles it every few days.
The astronomers who
found it say it’s likely there are other planets circling the same star,
a little farther away where it may be cool enough for water and life.
And those planets might fit the not-too-hot, not-too-cold description
sometimes call the Goldilocks Zone.
That means that in the star system Alpha Centauri B, a just-right planet could be closer than astronomers had once imagined.
It’s
so close that from some southern places on Earth, you can see Alpha
Centauri B in the night sky without a telescope. But it’s still so far
that a trip there using current technology would take tens of thousands
of years.
But the wow factor of finding such a planet so
close has some astronomers already talking about how to speed up a 25
trillion-mile (40 trillion-kilometre) rocket trip there. Scientists have
already started pressuring NASA and the European Space Agency to come
up with missions to send something out that way to get a look at least.
The
research was released online Tuesday in the journal Nature. There has
been a European-U.S. competition to find the nearest and most Earthlike
exoplanets — planets outside our solar system. So far scientists have
found 842 of them, but think they number in the billions.
While
the newly discovered planet circles Alpha Centauri B, it’s part of a
system of three stars: Alpha Centauri A, B and the slightly more distant
Proxima Centauri. Systems with two or more stars are more common than
single stars like our sun, astronomers say.
This planet
has the smallest mass — a measurement of weight that doesn’t include
gravity — that has been found outside our solar system so far. With a
mass of about 1.1 times the size of Earth, it is strikingly similar in
size.
Stephane Udry of the Geneva Observatory, who heads
the European planet-hunting team, said this means "there’s a very good
prospect of detecting a planet in the habitable zone that is very close
to us."
And one of the European team’s main competitors,
Geoff Marcy of the University of California Berkeley, gushed even more
about the scientific significance.
"This is an historic
discovery," he wrote in an email. "There could well be an Earth-size
planet in that Goldilocks sweet spot, not too cold and not too hot,
making Alpha Centauri a compelling target to search for intelligent
life."
Harvard planet-hunter David Charbonneau and others used the same word to describe the discovery: "Wow."
Charbonneau
said when it comes to looking for interesting exoplanets "the single
most important consideration is the distance from us to the star" and
this one is as close as you can get. He said astronomers usually impress
the public by talking about how far away things are, but this is not,
at least in cosmic terms.
Alpha Centauri was the first
place the private Search for Extra Terrestrial Intelligence program
looked in its decade-long hunt for radio signals that signify alien
intelligent life. Nothing was found, but that doesn’t mean nothing is
there, said SETI Institute astronomer Seth Shostak.
The
European team spent four years using the European Southern Observatory
in Chile to look for planets at Alpha Centauri B and its sister stars
Alpha Centauri A and Proxima Centauri. They used a technique that finds
other worlds by looking for subtle changes in a star’s speed as it races
through the galaxy.
Part of the problem is that the star
is so close and so bright — though not as bright as the sun — that it
made it harder to look for planets, said study lead author Xavier
Dumusque of the Geneva Observatory.
One astronomer who
wasn’t part of the research team, wondered in a companion article in
Nature if the team had enough evidence to back such an extraordinary
claim. But other astronomers said they had no doubt and Udry said the
team calculated that there was only a 1-in-1,000 chance that they were
wrong about the planet and that something else was causing the signal
they saw.
Finding such a planet close by required a
significant stroke of good luck, said University of California Santa
Cruz astronomer Greg Laughlin.
Dumusque described what it
might be like on this odd and still unnamed hot planet. Its closest star
is so near that it would always hang huge in the sky. And whichever
side of the planet faced the star would be broiling hot, with the other
side icy cold.
Because of the mass of the planet, it’s
likely a rocky surface like Earth, Dumusque said. But the rocks would be
"more like lava, like a lava planet."
"If there are any inhabitants there, they’re made of asbestos," joked Shostak.
Source from The News International
A new analysis of observations from NASA's Hubble Space Telescope found that the bright nearby star Fomalhaut does indeed host a huge exoplanet, which scientists dubbed a "zombie" world in an aptly Halloween-themed video on the alien planet. This conclusion contradicts other recent studies, which determined that the so-called planet — known as Fomalhaut b — is actually just a giant dust cloud.