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Have you ever wandered

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why some telescopes
are launched into space

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while others are built
on remote mountain tops?

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What is actually
the best for astronomy?

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Here we provide a ringside view

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of the fight for the elusive
photons from deep space.

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Is it a battle of the telescope giants?

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This is the Hubblecast.

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News and images from the
NASA / ESA Hubble Space Telescope.

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Travelling through time and space
with our host, Dr. J

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EPISODE 6: A battle of Giants.
Telescopes in space and on the ground.
a.k.a. Dr. Joe Liske.

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Welcome to the Hubblecast.

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When I was a kid, I often
used to stare at the night sky

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and wander
what it was all about.

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Back then, I usually
only used my eyes

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or at most
a pair of binoculars.

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But astronomers
have telescopes

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that are much more powerful
than the naked eye,

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and which can be used
to uncover

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the faintest and most distant
objects in the Universe.

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In today's Hubblecast
we will take a small detour

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from our usual flow of amazing
discoveries and images

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from the NASA / ESA
Hubble Space Telescope

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and look at the most fundamental
tool used by astronomers:

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the telescope.

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It all began nearly 400 years ago

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when Galileo Galilei
for the first time

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looked at the Universe
through a small telescope.

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This momentous occasion
will actually be celebrated in 2009

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which has been declared
the International Year of Astronomy.

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Today we have telescope
of many different sizes and shapes.

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Some are on the ground,

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like ESO's Very Large Telescope

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located in the remote
2,600 meter high mountain

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in the Atacama Desert in Chile.

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It's seen here

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in one of the most sophisticated
computer models ever made.

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Some telescopes are in space,

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like the Hubble Space Telescope

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in orbit around Earth almost
600 kilometres further up.

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So how does a telescope work?

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Well, common to
almost all telescopes,

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regardless of size or purpose,
is that that have a mirror,

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some instruments and
a few supporting systems.

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The main function of the mirror
is to collect as much light as possible

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from distant stars and galaxies.

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It is not to magnify anything
as many people think.

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Then, there are a number
of secondary mirrors

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that send the light
to the instruments.

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There are two main
types of instruments.

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First, there are cameras,

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which essentially do what
any normal digital camera does,

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they take images.

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And then, there are the spectrographs

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that spread the incoming light into
its constituent colours, like a rainbow,

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which can tell a lot about
the physics of distant objects.

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Ingenious engineers and imaginative
astronomers around the world

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compete in a scientific battle of
how to unveil the secrets of the Universe.

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So who is winning?

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Are the ground-based
telescopes better

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because they are larger
and collect more light

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from faint stars and galaxies?

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Or are the space-based
telescopes winning the race

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as they can make sharper images
above the clouds

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and the disturbing atmosphere?

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On that count, ground-based
astronomy is fast catching up.

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Advanced techniques
such as adaptive optics

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have been developed to correct

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for the atmospheric
blurring and twinkling.

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On the other hand,

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the atmosphere blocks
certain wavelengths of light.

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Only space telescopes,
like Hubble,

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that fly above the atmosphere

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can access the ultraviolet and
infrared parts of the spectrum

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which are invisible
from the ground.

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Ground-based telescopes
on the other hand

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can observe larger portions
of the sky in one go,

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and also usually have more
specialized instruments

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that are easier to change when
new techniques are developed.

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It would of course make for a much
more exciting Hubblecast episode

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if we could show you
a bloody battle

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between furious ground-based and
space-based astronomers.

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But in reality
there is no battle

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between ground-based
and space-based telescopes.

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Observing teams often use
combinations of different telescopes

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on the ground and in space

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to solve the riddles
of the Universe.

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So the bottom line is:
it's not a competition.

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It's the synergy
and complementarity

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between the different
kinds of telescopes that matter,

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whether they are small or large,

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in the Southern
or Northern hemisphere,

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on the ground or in space.

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What matters is that
they are all working

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towards a common cause:

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discovering the secrets
of the world around us.

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This is Dr. J
signing off for the Hubblecast,

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which, by the way,
from today onwards

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will be available in High-Definition
from spacetelescope.org.

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Hubblecast is produced
by ESA / Hubble

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at the European
Southern Observatory in Germany.

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The Hubble mission is a project
of international cooperation

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between NASA and
the European Space Agency.

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Thanks to: