The Largest Telescopes in the World

For some of us we've looked at getting a telescope, gone down to the street and seen telescopes going for prices between $200 all the way up to the fancy $8,000 mark. You know, the ones you look at dreaming that you could own or that your spouse would let you buy ;)

Well on a documentary entitled "Big, Bigger Biggest: Telescopes" it was mentioned that the 8m mirrors that went into the Large Binocular Telescope cost $10 million a piece and there are two of them!
While looking at telescopes like these I just wish I could afford one myself!

There are currently some very large telescopes scattered around the globe, some larger than others but not by much. Before having a look at some of the proposed telescopes to come it would be good to reflect on what we currently have to give a better appreciation of what is to come. Several of the current largest telescopes include:
Gran Telescopio Canarias
Keck
SALT

Gran Telescopio Canarias is a 10.4 meter telescope in the Canary Islands, Spain. The GTC is based on the design of the Keck telescope in that it's main mirror is made up of 36 smaller segments. It's a US$179 million telescope that began operations in 2007 although not officially opened until 2009. The GTC is at an altitude of 2,400 meters above sea level and it at this stage the largest optical telescope on Earth.

Keck is probably one of the more well known telescopes globally, although it is in fact two telescopes. Keck I and Keck II which are both 10 meter telescopes which can both work either on their own or together effectively one larger mirror. When both of these 10m mirrors work collectively they give the effective aperture of about 14m.

The Keck telescopes are located in Hawaii and have been running since 1993 and 1996 respectively at an altitude of 13,796 feet, 4,204m. Although Keck doesn't have the largest primary mirror in the world, the two of them combined does still make the largest optical telescope in the world.

Southern African Large Telescope (SALT) is the largest single mirror in the southern hemisphere and currently the third largest in the world. SALT is based on the design of Hobby Eberly Telescope but with some modifications to the design that allows it to have a larger field of view and effective collecting area. SALT is made of 91 individual 1.2m hexagonal mirrors which makes a mirror 9.8x11.1m . Unlike most telescopes SALT is designed to only move on one axis and is inclined at an angle of 37° from the horizon, designing the telescope in this way made is considerably cheaper even with the added complexity of the telescopes design. SALT is located at the South African Astronomical Observatory near Sutherland.

These are just a couple of the latest telescopes around the world at the moment but there are more to come, but that is a post for another day. For now though, just close your eyes and imagine being able to view the sky through a pair of binoculars like the Keck telescopes!

§ Colin

For additional reading:

http://astro.nineplanets.org/bigeyes.html

Image source:

https://www.sciencephoto.com/media/322000/enlarge
Credit: MAGRATH PHOTOGRAPHY/NIELSEN/SCIENCE PHOTO LIBRARY
Keck 1 and Keck 2