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Big Dish

September 11, 2016

A radio telescope in a big bowl is about ready to get to work. Construction was finished in July, and scientists have spent the last couple of months checking it out.

The telescope is known as FAST. It was built in a natural bowl-shaped depression in south-central China. It’s 500 meters wide — almost a third of a mile. That makes it the second-largest single-dish radio telescope in the world.

FAST is patterned after the Arecibo Telescope in Puerto Rico, which is also built in a natural basin. The terrain makes it easier to support the telescope, which forms a wide, shallow dish. It also provides some shielding from radio interference here on Earth.

That design means the telescope can’t move to follow astronomical objects as Earth spins on its axis. Instead, a tracking system above the dish moves, allowing the telescope to keep an eye on an object for up to a few hours. That design comes with a trade-off, though — astronomers can’t use more than 300 meters of the radio dish at a time.

Astronomers already have several projects lined up for the telescope. They’ll use it to map clouds of gas that trace the spiral arms of the Milky Way galaxy, for example. They’ll also look for pulsars — the rapidly spinning corpses of dead stars. And they’ll search for radio signals from other civilizations — adding a new tool in the search for extraterrestrial intelligence.

We’ll talk about how some small telescopes are searching for other planets tomorrow.


Script by Damond Benningfield

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