keck-interferometer

Do a HUMONGOUS telescope crossword!

Do a HUMONGOUS telescope crossword!

A humongous telescope, that is,
not a humongous crossword!

Crossword Instructions:

Put the mouse on a numbered square to see the clue. Click if you want to enter the word. For some squares, you may see both an Across Clue and a Down Clue. If you want to enter the word that goes across, hit the letter "a" first. If you want to enter the word that goes down, hit the letter "d" first. If you change your mind about entering a word, hit the ESCape key. You will earn points for every correct word. If you start a new puzzle before finishing the one you're working on, you will lose 40 points.

Boy and solar system poster

Just fill in the missing words to solve the crossword puzzle.

Keck Telescope dome

This is a picture of one of the Keck Telescopes, with its domed roof open. See the little, tiny person standing in the opening?



Making the Biggest Telescopes Even Bigger

The Keck kids

The two giant Keck Telescopes sit high atop an extinct volcano (called Mauna Kea) on the "Big Island" of Hawaii. Telescopes (except for radio telescopes) do better if they are as high up as possible. That way, they have less air to look through to see the stars.

Each of the telescopes uses a curved mirror to gather light from the night sky. Each mirror is 10 meters (about 33 feet) across. That's about the width of a tennis court! The mirrors are big because the bigger (and more perfect) the mirror, the better the image the telescope makes.

The Keck Telescopes are the largest optical instruments in the world!

Even better, the two mirrors can be used together to look at the same object in the sky. The images must be combined very precisely. But that combined image is MUCH better than one telescope alone could get. The image is almost as good as if it were made with a telescope mirror as wide as the whole distance between the far edges of the two telescopes' mirrors. In the case of the Keck Telescopes, this distance is 85 meters (280 feet). That's a mirror almost the length of a football field across! Can you imagine the domed roof you'd have to build over that?

This technique of combining the images from more than one telescope is called interferometry (in-ter-fear-AH-muh-tree).

How an interferometer works

NASA is hoping to make even better use of this technology by adding four more smaller telescopes on top of Mauna Kea. These four proposed "outrigger" telescopes would each have mirrors about two meters across. They would be placed in very precise positions. Then their images would be very precisely combined with the images from the big Keck Telescopes.

The "aperture" is the light-gathering part of the telescope, like the mirror. "Synthesis" means putting together. So this new telescope would be a giant "aperture synthesis telescope." It would be known as the Keck Interferometer.

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