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What do stars Twinkle?

This is a very good question. I found the answer in a wonderful astronomy book, "NightWatch" by a Canadian astronomer, Terrence Dickinson. You may have seen him on the Discovery Channel.

You are right about stars twinkling. But the interesting puzzle is why don't planets or the Moon twinkle? That answer is because stars are tiny pinpoints of light. Even the closest one is light-years away. Planets and the Moon, on the other hand, are much closer and so you are seeing a disk not just a pin point.

The Earth's atmosphere is always moving. It's as if we were looking at the sky through a jiggling bowl of jello. The ripples in the atmosphere are not large enough to distort a large image of a planet but the tiny dot of a star is smaller than the ripples and so twinkles.

During the Month of April, you will be able to see the planet Mars quite easily. Look in the Southern sky for a bright red object. It won't be twinkling as much as a star.

Answer #% % filename A222.DOC page% % page 1 of% % numpages 1 % % date \@ "MMMM d, yyyy"March 28, 1997

Kelly McLeish, room 11, Mrs. Pottery

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