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OBSERVING THE STARS ­ WHERE ARE
LARGE TELESCOPES BUILT?
· To see the stars more clearly, you need to go to a
place where there is no light pollution, a place
with clear skies with little dust or moisture in the
atmosphere
· Must be remote to avoid manmade pollution
· High altitude to minimise the distorting and
blurring effect of the atmosphere as much as
possible
· Must be a dry and low humidity location to
avoid the refraction of light be water particles
· Locations that observatories are situated in:
The Atacama desert in Chile, the Mauna Kea site in
Hawaii, Australia and the Canary Islands…read more

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OBSERVING WITH TELESCOPES
· To detect faint sources you need a wide
aperture as this will collect enough radiation
for us to see the object
· The bigger the aperture the more radiation
can get into the telescope and the better the
image formed
· Concave mirrors used by most astronomical
telescopes ­ easier and cheaper than making
a large lens
· Aperture size must be larger than
wavelength of the radiation detected by the
telescope ­ this reduces any effect of
diffraction which causes the image to blur…read more

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ASTRONOMERS USE LOCAL AND
REMOTE TELESCOPES
· Local telescope ­ can go to the telescope and
point it at what you want to look at
· Most telescopes are now computer controlled
· Advantages of remote controlled telescopes:
· Good for a survey ­ can be programmed to
do one
· No need to spend time or money to travel to
the telescope
· Can programme a telescope anywhere in the
world
· Without remote control, we wouldn't have…read more

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TELESCOPES IN SPACE - WHY ARE
TELESCOPES USED IN SPACE?
· The earth atmosphere ­ absorbs at least 10% of visible
light, other parts of the EM spectrum are absorbed
completely by the upper atmosphere and it also refracts
light and reduces the sharpness of images
· Way of improving this is to have the telescope outside to
the earth's atmosphere in space ­ this avoids absorption
and the refraction effects of the atmosphere as well as
being able to use parts of the EM spectrum that the
atmosphere absorbs
· Disadvantages of using telescopes in space ­ cost of
setting up, maintaining and repairing is very high and the
uncertainties of a space programme (the cost in
comparison to other costly priorities e.g. defence and
healthcare ­ the funding is never guaranteed. Also is when
one country ­ when a space programme is linked with
other countries - has cutbacks as this can have a knock
down effect on the others)…read more

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NEW TELESCOPES ­ HOW ARE THEY
PLANNED AND BUILT?
· As telescopes are very expensive to run the way to justify the
costs is to get them as used as much as possible
· To ensure this many organisations are involved in running and
building them ­ as a result many more astronomers have access
to them and can make observations
· Advantages : costs shared, economical and there is also a bigger
pool of expertise available for the organisations running the
telescope
· e.g. The Southern African Large Telescope (SALT). South
Africa, the USA, Germany, New Zealand, Poland and the UK are
involved. SALT has an 11 metre primary mirror and can detect
very faint sources, even a candle flame on the moon!
· E.g. The international Space Station ­ project led by the US with
the help of 15 other countries ­ the largest and most expensive
international science project in history
· Non ­ astronomical factors ­ cost of site, social and
environmental impact near the observatory, access to the site
and working conditions for employees…read more

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