Jeffery Smith, age 11, of Parker, Ind., for his question:

How many light years across is the galaxy?

Andy's readers know by now that one light year equals almost 6 million million ordinary miles. This figure is 6 followed by l2 zeros. This immense distance, you might think, should take a spaceman to the end of the cosmos. But the cosmos, so far as we know, has no limit, and one light year is merely a small step across it.

One light year would not take us even to the nearest star, which is more than 4 light years away. The width of out star studded galaxy is estimated to be at least 80,000 light years. Some estimates suggest that it may be wider, perhaps l00,000 light years from rim to rim through the teeming center of the whirling pinwheel.