Exoplanet could be smallest ever found: Experts
Scientists say they've identified a sun-like star with as many as
seven different planets - including one that might be the smallest ever
found outside the solar system. If confirmed, the planetary system
around HD 10180, a star more than 100 light years distant, would be the
richest ever discovered. One astronomer says it's part of a growing body
of evidence that the universe is full of planets - and that several
could be similar to our own.
"The really nice thing about finding systems like this is that it
shows that there are many more out there," said Alan Boss, of the
Washington-based Carnegie Institution for Science, who wasn't involved
with the find. "Mother Nature really had fun-making planets."
Although most of the planets identified are large - about 13 to 25
times the mass of our home - those behind the discovery, announced
Tuesday at an international conference in France, say they're nearly
certain they've identified one only 1.4 times the size of Earth.
Planets found outside the solar system are called "exoplanets" and
this would be the smallest one ever spotted.
Scientists have been successfully hunting exoplanets for about 15
years, and they've now catalogued some 450. But most finds have been
limited to one or two or three planets per star, usually gargantuan
balls of gas similar to Jupiter or Saturn.
But at up to seven planets, the new discovery nearly matches our own
solar system, which counts eight.
Christophe Lovis of Geneva University, one of the scientists behind
the find, said the first five were most comparable to Neptune.
"They are made essentially of rocks and ice. They have a solid core.
But on top of that is a layer of gas, of hydrogen and helium most
likely," he said. "They are probably not habitable." The sixth is
possibly a Saturn-like planet, while the seventh, the smallest, would be
so close to its star that its "year" would take just over a day.
Lovis and his team haven't been able to observe the planets directly,
which is typical. Few planets can be seen against the blazing light
given off by their much more massive parent stars.
The European Southern Observatory compares the challenge to "spotting
a dim candle in front of a raging forest fire."
So the scientists used the observatory's 3.6 meter (11.8 foot)
telescope at La Silla, Chile, to study the star itself.
AP
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