July 26th, 2015
Optical telescopes (the kinds that work with light, instead of radio or other waves) keep getting bigger and bigger. There’s a good reason for that: the larger the primary mirror that collects/reflects light, the better resolution an astronomer can achieve, allowing him or her to see more objects and peer further into the universe.
Here are the largest telescopes on the planet, which have so far topped out at a 10 meter diameter for the primary mirror (called an objective). However, a 21-meter telescopic monster, the Giant Magellan Telescope, is under construction, to be placed at Las Campanas Observatory, high in the Chilean Andes. And, if it survives a number of funding and community hurdles, the Thirty Meter Telescope (artist’s depiction, above) will scan the skies from the popular Mauna Kea site on Hawaii.
Gran Telescopio Canarias. At 10 meters, this scope is one of the world’s largest. Located in the largely light-pollution free Canary Islands, the telescope has identified the first stars as the universe was created, and the asteroid 2012 DA14 as it passed within 28,000 km of the earth.
Keck I and Keck II. Also at 10 meters, these twin telescopes are atop Mauna Kea, in (and on) Hawaii. Recently, scientists at the observatory created the sharpest image ever of a planet outside of our solar system (by 130 light years), and discovered water there.
SALT. Short for South African Large Telescope, is from 9 to 11 meters across (depending on how you measure such things). Astronomers here were, by collaborating with other sites, identify two huge planets in orbit around two suns.
Hobby Eberly. This 9.2 meter telescope is on Mt. Fowlkes, Texas, and works with spectroscopy only. The telescope has found one planet in orbit around a giant star, and astronomers there are using the scope to find multi-planet solar systems.
Large Binocular Telescope. Located on Mount Graham in Arizona, the LBT has two mirrors, each with a diameter of 8.4 meters. Using a new technique called adaptive optics, which reduces blurring from the earth’s atmosphere, the LBT obtained the clearest images ever of planets 127 light years away.
Subaru. No, not the car; this 8.2 meter telescope is run by the National Astronomic Observatory of Japan, and is located on Mauna Kea, Hawaii (near the Keck telescopes). Astronomers here obtained 3D images of a quasar in action, and found evidence of “Fullerenes” (large soccer-ball like carbon molecules) in outer space.
What about Hubble? The Hubble Space Telescope is not the world’s largest by any measure. But its small 2.4 meter mirror doesn’t have to pierce through the earth’s atmosphere to get spectacular images. It’s more than 300 miles above sea level.
Sources: Astro/nineplanets.org, hubblesite.org
extremely large telescopes, types of telescopes, astronomy in hawaii