Fast Facts About the GBT
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by Carolyn White
- The telescope helps us learn about stars, galaxies and other objects in
the Universe by collecting the radio waves they emit.
- Astronomers donít look through the telescope. Instead, electronic
detectors and computers take the radio waves the telescope collects and
turn them into pictures of the objects in space, or some other kind of
- The telescope is 485 feet (148 meters) tall - taller than the Statue of
Liberty and nearly as tall as the Washington Monument.
- It weighs 16 million pounds (7.3 million kilograms) - the same as 19 Boeing 747s.
- Despite its weight, the telescope can be pointed with an accuracy of one
arcsecond. Thatís equivalent to the width of a human hair seen six feet
(2 meters) away.
- The telescopeís surface is made up of 2004 metal panels and is almost 2
acres (8000 square meters) in extent - one and a half times the size of
a football field.
- To measure the positions of the panels, laser beams are shot down from the
telescopeís tall "feed arm" and reflected off small targets on the
dish surface. The panelís positions are adjusted precisely with
- To keep track of exactly where the telescope is pointing on the sky, laser
beams are sent up from the ground and reflected from targets on the
underside of the dish.
- The telescope works both night and day - the radio waves it collects
are not "drowned out" by the Sun.
- The telescope is designed to handle a great range of wavelengths, from 9
feet (3 meters) long down to 1/8th inch (3 millimeters).
- The telescope only receives signals from space, never sends them.