Southern African Large Telescope

Trip Start Jul 19, 2012
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Flag of South Africa  , Western Cape,
Thursday, January 10, 2013

There are about 18 observatories at the South African Astronomical Observatories, 2 of them are English scopes and we also share the newest and largest one SALT. SALT has 91 mirrors all joined to make one big mirror and 13 meters up from the mirrors is the tracker and primary focus and the light information is read by a computer and is sent to the floor below to be analysed by the astronomers. All the 91 mirrors are hexagonal shaped, one meter across and they need to clean them every day because they get layers of dust so the images would come out wrong. They use compressed carbon dioxide to clean the mirrors that looks like snow and picks up the dirt and rolls onto the floor.

A place like Betelgeuse, a star in Orion is so far away that even though we can see the light it may no longer be there. It is 640 light years from earth and a light year is how far light travels in a year.
Light travels 300,000 km per second so in a year it goes

300,000 x 60 x 60 x 24 x 365 = 9,460,800,000,000 km

Ford Prefect and Zaphod Beeblebrox from The Hitchhikers Guide to the Galaxy come from a planet somewhere in the vicinity of Betelgeuse.
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