Earth's sibling located...600 light-years away
Space and extra-terrestrial life have always been a source of wild flights of imagination and inspiration for humanity. Now there is a fresh reason to be excited. NASA says it has discovered a planet that is similar to ours. The exoplanet – or a planet lying outside our Solar system – is about 2.4 times bigger than Earth and is spinning around a star not unlike the Sun.
It was first spotted in 2009 and became one of 54 so-called candidate planets aspiring to the title of Earth’s twin. Known as Kepler 22-b, it was discovered by the Kepler space telescope, designed to search for exoplanets as small as Earth, including those orbiting stars in a warm habitable zone where liquid water could exist on the surface of the planet. Kepler 22-b is the first that the US space agency has been able to confirm as fulfilling these criteria.
Confirmation means that astronomers have seen it crossing in front of its star three times and the planet seems to meet all the main requirements for sustaining life. There may be water, but that does not mean that anyone knows whether life actually exists there – simply that the conditions are right.
According to NASA, Kepler 22-b is in the not-too-hot and not-too-cold habitable zone spinning around its sun at a distance about 15% smaller than the distance between the Earth and the Sun. Its year is about 290 days long; however its sun gives about 25% less light, leading American scientists to suggest that the planet’s temperature may be a comfortable 22 degrees Celsius. However, its surface may prove to be rocky or gaseous as well as liquid.
Vladimir Surdin, a Senior Fellow from the Sternberg Astronomical Institute in Russia, told RT that one should be very careful when guessing at conditions on a faraway planet.
“The main thing that attracts everyone about Kepler-22b is its alleged temperature. But I wouldn’t stake my head on it. For example, initially, there were suggestions that the temperature on Venus was about 60-70 degrees Celsius and it turned out it’s more than 500!”
News of the discovery has raised secret hopes that the planet could become a backup home for inhabitants of an Earth which is deemed by many to be severely overpopulated. However, experts say it is hardly a realistic scenario.
“It’s about 600 light-years from Earth – a distance that none of the contemporary or even any foreseeable future spacecraft would be able to cover. If we were to start looking for a backup planet, it would have to be within our own Solar System,” – says Surdin.
Russian scientists say finding Kepler 22-b is an undeniably great discovery – but is of purely scientific interest.
It brings to three the total number of exoplanets that could sustain life confirmed by global astronomers.
In addition to French astronomers' confirmed finding of Gliese 581d in May, Swiss astronomers reported in August that another planet, HD 85512b, about 36 light years away, seemed to be in the habitable zone of its star.
However, those planets are "orbiting stars smaller and cooler than our Sun," NASA said in a statement, noting that Kepler-22b "is the smallest yet found to orbit in the middle of the habitable zone of a star similar to our Sun."
The Habitable Exoplanets Catalogue – a new online database for scientists and the general public– is a first attempt to categorize habitable exoplanets and exomoons. It ranks the habitability of planets according to three main criteria: surface temperature, similarity to Earth and capacity to sustain organisms at the bottom of the food chain.