Billions of Earths

There could be one hundred billion Earth-like planets in our galaxy, a US conference has heard.

Dr Alan Boss of the Carnegie Institution of Science said many of these worlds could be inhabited by simple lifeforms.

He was speaking at the annual meeting of the American Association for the Advancement of Science in Chicago.

So far, telescopes have been able to detect just over 300 planets outside our Solar System.

Very few of these would be capable of supporting life, however. Most are gas giants like our Jupiter; and many orbit so close to their parent stars that any microbes would have to survive roasting temperatures.

But, based on the limited numbers of planets found so far, Dr Boss has estimated that each Sun-like star has on average one “Earth-like” planet.

This simple calculation means there would be huge numbers capable of supporting life.

“Not only are they probably habitable but they probably are also going to be inhabited,” Dr Boss told BBC News. “But I think that most likely the nearby ‘Earths’ are going to be inhabited with things which are perhaps more common to what Earth was like three or four billion years ago.” That means bacterial lifeforms.

Dr Boss estimates that Nasa’s Kepler mission, due for launch in March, should begin finding some of these Earth-like planets within the next few years.

Recent work at Edinburgh University tried to quantify how many intelligent civilisations might be out there. The research suggested there could be thousands of them.

CO2 found on exo-planet

I need to get back to some science. Fortunately, CO2 was recently detected on an exo-planet.

NASA said its Hubble Space Telescope has discovered carbon dioxide in the atmosphere of “hot Jupiter” planet HD 189733b, which orbits a nearby star 63 light-years from Earth.

The planet is itself too hot to support life — its surface is about 1,800 degrees F (1,000 degrees C).

But the astronomers said the observations are a proof-of-concept demonstration that the basic chemistry for life can be measured on planets orbiting other stars.

So the CO2 itself doesn’t mean anything particularly important, but it does lend credence to the idea that it is only a matter of time before astrobiology becomes an enormous field. How exciting would it be to finally confirm that we aren’t all alone, afterall? Granted, we may never make contact with any life we find, most obviously if it isn’t intelligent, but also simply because it may be so far away. This CO2, for example, was produced at 63 years ago. Assuming there was life that close (which would be almost as tremendous as the discovery of the life itself) – and it was intelligent – it would be 126 years before we could make two way contact; that’s 63 years for our (presumably) radiowaves to travel at the speed of light, reach the life-bearing planet, and then 63 years for a return message, provided the exo-life even gave a damn.