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OSB archive

E-ELT: Big eye opener

Pete Wilton

Today Oxford's Isobel Hook will be telling attendees at the JENAM astronomy meeting all about the European Extremely Large Telescope [E-ELT].

Sometimes scientists are guilty of hyperbole in the naming of instruments but in this case 'extremely' is entirely justified as, with a mirror 42m in diameter, the E-ELT would be four times bigger than the biggest optical telescopes in use today [the Southern African Large Telescope, for instance, has a 10m mirror].

Why is mirror size important? Because for optical astronomers the size of your mirror determines the sharpness of your image - roughly speaking a mirror four times the size gives four times the sharpness - making it possible to see much smaller objects.

This is especially important in the search for exoplanets, planetary bodies orbiting other stars. Massive instruments such as E-ELT would offer the first realistic chance of directly imaging 'normal' [ie non-massive, non-luminous] planets like the Earth.

The E-ELT would also enable us to do some very cool galactic navel-gazing, staring into the heart of our own Milky Way to see whether it harbours a supermassive black hole as part of an Active Galactic Nucleus [AGN].

Isobel Hook, of Oxford's Department of Physics, is leading the science case for E-ELT and tells me that the aim is to create a flexible instrument that could perform a wide variety of experiments.

The wide range of science such a telescope could do is a powerful incentive to overcome the many technical and logistical challenges in building a telescope quite this big.

In fact the E-ELT is only possible because of advances in the field of adaptive optics, making it possible to combine the light from hundreds of smaller mirrors into a single image (rather like an insect's compound eye).

Let's hope E-ELT is successful so we can see what we can see...