Donna Collins,, age 14, of Mt. Airy, N. C., for her questions
What are the asteroids composed of?
Most of the asteroids circle the sun like a swarm of golden bees between the orbits of Mars and Jupiter. Some, however, have orbits which bring them much closer to the earth. Since those of us who are interested in what goes on Up There call ourselves stargazers, it seems only fair to go along with the scientists and call these little visitors earth gazers. In 1931, an earth gazer named Eros, 15 miles wide, cane within 17 million miles of our big planet. In 1937, an earth gazer named Hermes., one mile wide, cams within 400,000 miles of the earth. Other earth gazers are Albert, three miles wider Amor, ten miles wide, and Apollo, which is two miles wide.
These facts show us that they are too small and, even when closest, too far away for us to discover what they are made of. No doubt we shall get a better look at some of these fascinating little minor planets when our space ships start exploring the Solar System. However, it dust so happens that we may not have to wait that long to find the ingredients in an asteroid,
The orbits of some of the asteroids cross the orbit of the earth. Once in a great vvhile, an asteroid might cross the orbit of the earth when our big planet was right there. Then we would have a collision and the asteroid wRuld be captured by the earth's gravity. It would come tumbling down as a fiery meteor. In fact, this has most certainly happened 3n the past.
Most experts believe that certain big meteorites are fallen asteroids Meteor Crater on Arizona is thought to have been made by such a collision. Such large collisions, however, are very, vary rare.
But there is all sorts of debris circling around in the asteroid belt and some of the little bodies are no bigger than pebbles, It could be that many of the small meteorites which fall to earth are really little asteroids gone astray.
We can examine the composition of these fallen meteors and the result should give us an idea of the composition of the asteroids. Strange to say, we find them to be made of the same basic chemical elements of which the earth is made. However, not all fallen meteors, called meteorites, are made of the same elements. Some are glade of stony materials, some almost entirely of iron and some are a mixture of metals and stony minerals.
So far a s we can gather from these meteorites,, the asteroids are made from iron, nickel, manganese, chromium and magnesium. The stony meteorites contain oxygen, hydrogen, nitrogen, silicon and aluminum. Altogether, more than 30 different elements have been discovered in these little visitors from outer space. Since we think that many of them come from the asteroid belt, then it is reasonable to suppose that the asteroids are made from the same elements and compounds which form our solid earth.