Interferometry
An old adage says that two heads are better than one -- two people working together can produce sharper results than one person working alone. Now that may not always be true with people, but it's certainly true with telescopes. Combining the views from two or more telescopes can produce a far sharper view of the universe than is possible with one telescope alone.
This technique is called interferometry. Radio astronomers have used it for decades. They gather energy from a single astronomical object using several radio antennas. Computers then combine the signals to produce a picture of the object.
The clarity is comparable to having a single giant telescope, but at a fraction of the cost. If the dishes are spaced a couple of miles apart, then it's like having the clarity -- though not the raw light-gathering power -- of a telescope that's a couple of miles across.
Astronomers are applying this technique, called long-baseline interferometry, to optical telescopes, too. They've built test instruments in Arizona, California, and elsewhere. And they've created a giant interferometer by combining the two Keck telescopes in Hawaii. Each has a mirror that's more than 30 feet in diameter, so the Keck Interferometer can see remote, faint objects with extraordinary sharpness.
In a few years, astronomers hope to put an interferometer in space to search for planets around nearby stars -- including planets like Earth. More about SIM-Planet Quest tomorrow.
Script by Damond Benningfield, Copyright 2005
For more skywatching tips, astronomy news, and much more, read StarDate magazine.
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