Science News

System of Earth-sized planets spotted

Fri, 30th Jan 2015

Chris Smith

A clutch of Earth-sized planets discovered around a star 100 light years from Earth means the odds of extraterrestrial life existing have just increased dramatically. Ancient solar system

Using the Kepler space telescope, Birmingham scientist Tiago Campante and his colleagues were able to see tiny dips in the intensity of the light coming from the star Kepler 444. These corresponded to 4 planets, the smallest about the size of Mercury and the largest about the size of Venus, passing at various points in front of Kepler 444 and partially blocking out the light from the star.

The discovery is ground-breaking on two levels. It shows that tiny planets of Earth-size can be detected, according to Campante, "with a precision of within a few tens of miles." More importantly it re-writes the astronomy books because the parent star, Kepler 444, is more than 11 billion years old.

Previously scientists had thought that rocky planets like the Earth couldn't exist this long ago because, so soon after the Universe had formed (a couple of billion years previously) there would have been too few raw materials, like heavy metals such as iron, to seed them.

This is because heavy elements, like iron, are made inside massive stars and then dispersed across the Universe when the star explodes in a supernova at the end of its life.

However, the existence of these newly-discovered rocky worlds shows that Earth-scale planets can and did form this early in the evolution of the Universe, which also means that the odds of an Earth-like planet existing, with liquid water and other correct chemistries needed for life, are significantly higher than previously thought.

At the moment the Birmingham team, who have published their findings in the Astrophysical Journal, don't know the compositions - or what is in the atmospheres, if any, of the planets they have found, but these sorts of studies are on-going by groups internationally.

"It will be an interesting and important next step," says Campante.


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Just because we are now aware of a planet that might be suitable for alien life, the probability that there is alien life has not changed.  Whether we are aware of it or not does not affect the chance of it existing!  The planet exists whether we know about it or not..... 2dogmom, Fri, 6th Feb 2015

I want to know is there any other planet's creatures know the existence of human
diethyl, Fri, 6th Feb 2015

Actually that isn't strictly true, because, as I point out in the piece, these planets are extremely ancient (11 billion years); previously, scientists had thought that rocky planets could not exist this far back in time. The great age of these worlds indicates that the elapsed time during which life could have evolved on other planets across the Universe is therefore far larger than we had anticipated. This means that previous figures for the likelihood of the existence of extraterrestrial life are likely to be an under-estimate. chris, Thu, 19th Feb 2015

What I meant was the the probability of those planets existing has not changed, just OUR perception of whether they existed or not has changed.  OUR CALCULATION of the probability of life existing may be changed, but the actual probability has not.  Either life exists on other planets or it doesn't.  Nothing that we learn or do will change that.  2dogmom, Wed, 11th Mar 2015

Agreed. I don't think that extraterrestrial life is anything like Schrödinger's cat--our knowledge about it has no bearing on the actual truth. chiralSPO, Thu, 12th Mar 2015

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