If another planet has life
We are saved Not lost
Nor alone
Part of something greater
But only if they come
To liberate our madness
Is our evolution assured
For if we go to them
With our terrored enquiries
They will shoot us down
Alok Jha, science correspondent -
theguardian.com, Monday 4 November 2013 20.00
Our galaxy probably contains at least two billion planets that,
like Earth, have liquid water on their surfaces and orbit around their parent
stars in the "habitable zone" for life. The nearest, according to
astronomers, could be a mere 12 light years away.
A new study, published today in the Proceedings of the National Academy
of Sciences, suggests that Earth-like planets capable of supporting life are
far more common than previously thought. Using measurements from Nasa's Kepler
space observatory, scientists led by Erik Petigura the University of
California, Berkely, estimated that 22% of our galaxy's sun-like stars had
rocky planets circling them that were within the zone that meant they got
roughly the same amount of light energy as Earth gets from the sun. There are
around 100bn stars in our galaxy, of which 10% are like the sun.
So far Kepler has studied more than 150,000 stars and identified
more than 3,000 candidate planets, but many of these are "gas
giants", similar to Jupiter, that orbit close to their parent stars. If
there is life out there, it is far more likely to have evolved on rocky planets
with liquid water on their surfaces, similar to Earth.
