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Thursday, 23 February 2017
Discovery of new planets is a lottery win for astronomers looking for alien life
Known as TRAPPIST-1, the star itself is small, and shines with a feeble
red light. The planets are bunched together to take advantage of this
light and heat.
Photograph: NASA/PA
The seven potential habitable planets around a single star are a lottery win for astronomers looking for life beyond Earth
Seven potentially habitable planets found around a single star – this
latest exoplanet discovery is just mind blowing. As a fellow journalist
just said to me, “It’s like Battlestar Galactica come true!” She was
referring to the science fiction series’ twelve human colonies that were
supposedly on planets circling the same star.
Each one of the worlds announced today is roughly the size and mass
of the Earth. Incredibly, they all orbit the same star and each one sits
in the habitable zone of that star.
The habitable zone is the region around a star in which a planet
could be kept warm enough to allow liquid water to exist on its surface.
Known as Trappist-1, the star itself is small, and shines with a
feeble red light. The planets are bunched together to take advantage of
this light and heat. The nearest orbits in just 1.51 days, while the
furthest takes 12.35 days. I’m willing to bet that we are going to hear a lot about this planetary system in the years and decade to come.
At the most fantastical end of the possibilities, each of the seven
planets could host life. Even at the more mundane end of the
speculations, the collection presents scientists with an precedented
laboratory in which to study planetary habitability. There is so much to
learn.
We still do not know definitely why the Earth is a living planet,
while Venus and Mars are not. We have our ideas – perhaps Venus is too
close to the sun, and Mars is too far away and too small – but these
ideas need testing.
The “seven sisters” of the Trappist-1 system provide us with the
perfect test ground. The planets will serve as examples to be studied
for their similarities and differences. And their discovery could not
come at a better time.
Next year, the James Webb Space Telescope
(JWST), will launch into space. It will be the largest space telescope
yet. At just 39 light years away, TRAPPIST-1 and its seven planets will
be visible, and JWST will allow astronomers to analyse these worlds’
atmospheres. The key constituent they will be looking for is water
vapour.
As far as we know, water is an absolute pre-requisite for life. It
was the failure to find water vapour in the atmosphere of Mars at the
turn of the twentieth century that put paid to dreams that the Red Planet was inhabited by a canal-building civilisation.
The
first exoplanet around a sun-like star was discovered in 1995. It was a
giant planet similar to Jupiter in our own Solar System. Since then,
astronomers have been detecting smaller and smaller worlds. Now the
discovery of Earth-sized bodies is almost routine. In August 2016, an Earth-sized world was discovered around the nearest star to the sun.
Ultimately, the study of exoplanets is the study of how planets
“work” in order to place our own world into context. By seeing the
variety of states in which an Earth-sized planet can end up, we will
better be able to understand climate change, planetary evolution, and
maybe what makes Earth habitable in the first place.
The coming decade will belong to the study of exoplanets. A variety
of space missions and ground-based telescopes will finally move the
field on from simply discovering that these planets exist to taking
readings of their atmospheres to assess them for habitability.
In so doing, we stand to learn a lot about exoplanets, a lot about
Earth, and a lot about our place in the universe. Exciting times. Stuart Clark is the author of The Search for Earth’s Twin (Quercus).
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