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We live in a Universe
of unimaginable scale

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and almost
incomprehensible beauty.

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How is the light from stars,
galaxies and nebulae

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fashioned into the
spectacular images

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that have so inspired us
over the years?

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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 10: Making the Universe come to life.
Behind the Hubble images
a.k.a. Dr. Joe Liske.

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Welcome to the Hubblecast.

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Do you ever look at this
beautiful Hubble images

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and wonder
how they were made?

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What exactly happens after the
faint light from distant objects

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is detected by Hubble?

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How are these cosmic photons
captured in space

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transformed into the
glorious coloured images

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down here on you wall
or your computer screen?

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On a clear night when we
look up into the heavens

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we can see the light
from thousands of stars.

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Our eyes are
fantastic detectors

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but in reality they are
actually very limited.

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They aren't sensitive enough
to peer out very far into space.

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Also, we can only see
visible light,

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but not ultraviolet or infrared
light like Hubble can.

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That's why for professional
astronomers the Hubble Space Telescope

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is such an exciting tool
to probe the Universe.

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Sitting at its vantage point
600 km. above the Earth

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Hubble is a window
on the Universe.

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The journey to make
a Hubble image

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begins when light
from a distant object

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starts on its way towards us.

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After travelling across
the vast distances of space

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it is captured by Hubble with
its 2.4 metre wide mirror.

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The light is then sent to one
of Hubble several cameras

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where the photons are turned
into an electrical charge

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by a CCD chip rather similar
to the ones in digital cameras.

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The Advanced Camera for Surveys,
for example,

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contains over 16 million
picture elements or 'pixels'.

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These act as miniature 'buckets'
to collect the light.

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The camera then reads out
how much light

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has been captured
in each bucket,

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the charge within
each of the pixels,

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and that puts an image.

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This readout is then
beamed back to the Earth

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as a series
of encoded numbers

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that are stored in archives
in the US and Europe.

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Hubble's cameras image the
Universe through different filters,

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like this one.

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These select specific
wavelengths of light

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that are characteristic
of different physical processes

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which may be going on
in different parts

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of distant galaxies and nebulae.

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Each of these filters results
in a single gray-scale image

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which is then assigned a colour.

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This colour is usually chosen
to more or less correspond

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to the actual colour of the filter,
although this is not always true.

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Anywhere between two
and six of these images

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are then combined to create
the final colour image.

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Take this view of the
colliding Antennae Galaxies.

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Hubble imaged
this merging pair

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through red, green
and blue filters

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to reveal the different components
inside the galaxies.

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For example, the red light
is coming from old stars

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and glowing hydrogen gas,
while the blue light

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is showing the violent
star formation

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triggered by
the cosmic collision.

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The red, green and blue
images are then combined

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to create the final
multi-colour image.

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One of the challenges
in making images

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is that there is a huge range
of brightness in nature

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from faint to bright objects

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and astronomical images
are so rich in information

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that our eyes and computer screens
cannot show their full content.

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Nature can be difficult to capture
in a single photograph

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and most of us have encountered
situations like the following.

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Imagine you try to take
a picture of a landscape.

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When you do so you can either
capture the bright parts of the sky

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or the darker parts of the vegetation,
but rarely both together.

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The job of the image
processing specialists

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is to compress this range
of brightnesses together

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so that we can see
all the nuances.

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Image experts use
the program FITS Liberator,

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pioneered be ESA,
ESO and NASA,

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to produce the
magnificent rich image

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which can be interpreted
by our eyes.

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Warning!

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10 x slower in reality!

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Making Hubble images
is fun & highly addictive!

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Google FITS LIBERATOR

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But is this what we
would see with our eyes

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if we could look
through Hubble?

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Well, not really.

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Look at this image
of the Cigar Galaxy.

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This is what Hubble
sees in visible light.

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Our eyes aren't actually
sensitive enough

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to be able to detect the faint
light from this distant object

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even when looking
through a telescope.

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The reason why Hubble's
instruments can do it

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is because they can gather
and add up the light

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over an extended
period of time,

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which is something
our eyes can't do.

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Furthermore, some telescopes
can 'see' wavelengths

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that we can't see
with our eyes.

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This multi-wavelength view
shows us much more

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than our eyes or anyone
telescope can see.

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Parts of this image were made with
the Chandra X-ray observatory in X-rays

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and part with the Spitzer Space
Telescope in infrared light.

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In this episode we have seen
how the images

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that have amazed and
intrigued us are created.

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You too can have a go
at making your own images,

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just Google
for 'FITS Liberator'.

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This is Dr. J
signing off for the Hubblecast.

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Once again, nature has surprised us
beyond our wildest imagination...

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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.