
European Extremely Large Telescope given go-ahead - Trey-Jackson
http://www.bbc.co.uk/news/science-environment-18396853
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jere
>Its sensitivity and resolution should make it possible to image directly
rocky planets beyond our Solar System.

This is unprecedented, right? I have been wondering for a while if such a
thing is or will be possible. I assumed the distances were simply too great.

I see now that it is possible to directly image gas giants, but not to my
knowledge small rocky planets.

<http://en.wikipedia.org/wiki/Direct_imaging#Direct_imaging>

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excuse-me
Pretty much yes.

Best wayto image rocky planets is in the mid-IR where they are brighter and
their parent star is less bright.

Mid-IR detectors weren't very good 30years ago when todays large telescopes
were planed and the mid IR telescopes that have been built were based around
poor detectors from 30years earlier and so are small.

Of course what you claim a telescope is for and what is the fashionable topic
once it's running can be different. That's the nice thing about telescopes
compared to say an LHC - decades after they open they are finding new unusual
things with new instruments.

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Gring
Wow. How many photons that bounce of the planet, travel a few lightyears and
get caught in this 40m mirror are we talking about here? 1 million per night?
Are we close to the limits of detection or what else is possible?

~~~
splat
A million photons would be overkill for a solid detection. A standard CCD
saturates at about 65,000 counts (or about that many photons, assuming the
efficiency is high). A source that is detected well enough to do interesting
measurements usually has a ~1000 - 20,000 photons per pixel. Spread out over
~15 pixels, a good detection could require as few as ~15,000 photons.

In this particular application it would be more difficult since you not only
have to detect the source on its own, you have to block out the glare from the
parent star. Usually the main problem in this sort of work is making sure that
the source you are detecting is actually a real thing and is not just an
artifact from the way you block out the light from the parent star.

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sjwright
How will this compare to the Square Kilometer Array?

<http://en.wikipedia.org/wiki/Square_Kilometre_Array>

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Tuna-Fish
SKA is a radio telescope, E-ELT will work with visible light, and as such,
they would be usable for very different targets.

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cromwellian
I wish the Terrestrial Planet Mapper and Terrestrial Planet Imager had been
funded. It was proposing to fly an armada of nulling interferometers in space
using optical interferometry capable of imaging planets around other stars at
25x25 pixel resolution.

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ktizo
I love these kind of naming conventions. I wonder what the next one in the
series will be called and if FLT has been used yet.

~~~
mburns
<https://en.wikipedia.org/wiki/Overwhelmingly_Large_Telescope>

