World’s largest telescope will search heavens for habitable planets like Earth
The European Extremely Large Telescope will be the first optical
telescope capable of picking out the weak pinpricks of light that are
reflected from planets as they orbit stars.
Astronomers claim the huge instrument, which will house a mirror the
width of five double decker buses placed end to end, will be able to
spot rocky Earth-like planets up to 100 million million miles away.
The telltale signatures in the light coming from such planets could
also reveal whether there is water on their surfaces, which gases are
in their atmospheres, and even if they may harbour life itself.
It will be the first time planets outside our own solar system have
been seen using light from their surface. Current telescopes are not
powerful enough to detect even giant planets in this way as the light
they reflect is overwhelmed by far brighter stars.
The 1 billion euro (£700 million) E-ELT will have more mirror glass than all the other telescopes in the world put together.
It is expected to be so powerful that if astronomers were to use it
to peer at the Moon, they would be able to see the car sized lunar
rover that was left on the moon by astronauts during the Apollo
With such high resolution, scientists believe they will be able to
see Earth-like planets that orbit stars within a region known as the
habitable zone, an area far enough away from the star around which it
orbits to not be too hot to support life, but also not to far away and
As astronomers this year celebrate 400 years since Galileo first
used a telescope with a lens just an inch wide to study the heavens,
British scientists on Thursday presented the detailed scientific case
for building the new giant telescope which will be four times larger
than any other telescope yet built.
Isobel Hook, joint chair of the E-ELT science working group and an
astronomer at Oxford University, said: “The astronomy community has
been moving towards building progressively bigger telescopes to get
“The resolution of the ELT is going to allow us to see objects and
structures in the universe that we have been blind to until know.”
There are currently 344 known planets outside our own solar system
which have been detected indirectly by looking for changes in light
coming from stars as the planets pass in front of them. Almost all are
gas giants similar to Jupiter.
The E-ELT, which will gather more than 15 times more light than
telescopes currently in operation, will be able to directly see small
rocky planets as they orbit their stars.
By analysing the spectrum of the light reflected from these planets,
it should also be possible to determine whether they have water or even
vegetation on the surface.
Professor Andrew Cameron, an astronomer at University of St Andrews,
said: “If they live up to the design goal, we will be able to detect
Earth-like planets tens of light years away.
“There are lots of stars within that range, so there is real
potential for finding a terrestrial planet that could sustain life.”
Construction of the E-ELT, which is being funded by the European
Southern Observatory, an international research organisation made up of
14 European countries including Britain, is expected to start in 2010
and the telescope is due to be operational by 2018.
A decision on where the telescope will be located is to be taken at
the end of this year. Candidates include La Palma in the Canary Islands
The E-ELT will use 906 hexagonal segments – each four and a half
feet across – that will be pieced together to work together as a single
mirror housed inside a giant rotatable dome. Each segment will have to
be continually adjusted by computers to produce a single image.
In the past, optical telescopes on Earth have also been hindered by
turbulence in the atmosphere which can leave images of stars and
galaxies slightly fuzzy.
This problem led to astronomers building expensive space telescopes
like the Hubble Space Telescope which can operate outside of the
Astronomers behind the E-ELT, however, plan to use new technology that could make future space telescopes unnecessary.
They propose to use powerful lasers positioned at several points
around the giant mirror that will be fired more than 55 miles up
through the atmosphere to create a faint “artificial star”.
This artificial star can then be used to measure the level of
blurring that the atmosphere is causing and a special deformable mirror
can be adjusted to compensate.
Scientists claim this will allow them to achieve some of the
clearest images of our universe ever achieved from the surface of the
Colin Cunningham, director of the E-ELT programme in the UK, said:
“There will be more glass in this telescope than there is in all the
other telescopes currently in use around the world put together.
“The detail it will allow us to see is four times greater than we can currently get. It is very exciting.”