Download telescopes timeline - Institute of Astronomy

A TIMELINE OF THE LARGEST OPTICAL TELESCOPES
[to be displayed along a timeline, which moves from bold line into dashed one progress from
past telescopes to planned ones]
-
Stephanie to add pictures of telescopes for Amanda
And to create a plot of primary aperture against date.
THE NORTHUMBERLAND – 1838
For a (very) brief period of time, the Institute of Astronomy’s very own Northumberland
telescope, with an aperture of 11.6 inches (28cms) and a length of 19ft 6in, was the largest
refracting telescope in the world. Even when it was built however, there had been larger
telescopes in existence and even larger ones planned. These were reflecting telescopes; by
using a mirror rather than a lens as the collecting area, more powerful telescopes could be
built both due to the shorter focal length required and the fact that a large reflecting mirror
could be supported from underneath, unlike a large lens. So, how much larger can these
reflecting telescopes get?
THE ROSSE SIX FOOT TELESCOPE – 1845
The Rosse telescope, more often referred to as ‘the Leviathan’, was built by William Parsons,
the third Earl of Rosse, in Ireland. The primary mirror had a diameter of 1.8m, making it the
largest telescope in the world until it was dismantled in 1908. Parsons used his telescope to
observe nebulae catalogued by earlier astronomers.
THE HOOKER 100’’ TELESCOPE - 1917
The Hooker has an aperture of 2.54m (100 inches), and is located at the Mount Wilson
Observatory, California. This telescope was used by Edwin Hubble to measure the redshift
and velocity of distant galaxies, the results of which led him to conclude the Universe is
expanding.
THE HALE 200’’ TELESCOPE - 1948
The Hale 200’’ was the largest effective telescope in the world for almost 50 years, and is still
actively used for scientific research today. With a mirror of 5.1m in diameter, it is the largest
telescope at the Mount Palomar Observatory, in California.
THE KECK TELESCOPES – 1993
Keck is composed of two telescopes (I and II), both with an aperture of 10m, located near the
summit of Mauna Kea, in Hawaii. The huge aperture was made possible by the development
of the segmented mirror; rather than one 10m-diameter reflector – which would not be able
to support its own weight – the primary mirror is actually 36 smaller mirrors that move
together to act as one. The two telescopes can be used individually, but also can operate
together to act as an interferometer, giving greater resolution.
THE VERY LARGE TELESCOPE – 1998
ESO’s (European Southern Observatory) VLT is actually 4 telescopes, each with an aperture of
8.2m, and as with Keck, each of the primary mirrors is segmented. Although individually
smaller than the Keck telescopes, when used together they currently give the largest photon
collection area in the world. The VLT is located at the Paranal Observatory in the Atacama
Desert in Chile.
THE GRAN TELESCOPIO CANARIAS – 2009
The GTC, or GranTecan, saw first light in summer 2009, and is located on the island of La
Palma, in the Canary Islands. It has a segmented primary mirror of 10.4m diameter.
THE GIANT MAGELLAN TELESCOPE (~ 2018)
The Giant Magellan Telescope (GMT) is the first of the next generation of extremely large
telescopes. It will use seven 8.4m-diameter mirrors – the first of which has already been cast –
to mimic a single primary with the resolving power of a 24.5m aperture. It will be built in at
the Las Campanas Observatory, in Chile, the home of the smaller Magellan telescopes.
THE THIRTY METRE TELESCOPE (~ ESTIMATED COMPLETION 2018)
Unsurprisingly, the TMT is planned to have an aperture of 30m and originates from a design
in the 1990s for the California Extremely Large Telescope. After considering a shortlist of five
locations - three sites in Chile, one in Hawaii and one in Mexico – the site where the TMT
will be built has recently been selected as Mauna Kea, in Hawaii.
THE EUROPEAN EXTREMELY LARGE TELESCOPE (~ 2020?)
The E-ELT is the next generation of telescope planned by ESO (European Southern
Observatory), probably to be located in Chile, along with the VLT. The design for the E-ELT
currently has an aperture of 42m, making it overwhelmingly larger than any other telescope,
built or planned.