November 10, 2012
WASHINGTON (AFP) - A newly-discovered alien planet seven times bigger than Earth may be able to support life, astronomers wrote in a study appearing in the journal "Astronomy and Astrophysics."
The planet, dubbed HD 40307g, is one of only a few to be discovered in the "habitable zone": a sweet spot, neither too close or too far from its sun, where liquid water could exist.
The so-called "super-Earth" orbits its star -- HD 40307, a dwarf just slightly smaller, cooler and less bright than our Sun -- every 200 days.
It is relatively close to the solar-system neighborhood, just 42 light years away. A light year is equivalent to about 9,460 billion kilometers.
"The star HD 40307 is a perfectly quiet old dwarf star, so there is no reason why such a planet could not sustain an Earth-like climate," said astronomer Guillem Anglada-Escude of the University of Goettingen in Germany.
The next step is to use powerful telescopes to study the planet more closely.
A large number of observations will be necessary to confirm any other similarities with Earth, the astronomers said.
The study noted that the distance between the planet and its star is similar to that between the Earth and the Sun and that it is likely the planet rotates on its axis, which would create a day and night cycle like ours.
So far, some 846 planets have been found outside our solar system since 1995, using high-powered equipment, most notably the Kepler telescope, launched in March 2009 to search for Earth-like planets.
Most of the discoveries are of planets far larger than Earth.
The study can be seen online at the site arxiv.org/archive/astro-ph.
