Jeanne Keller, Age 13, Of Nashville, Ill.., for her question:

What causes a halo of light around the moon?

Sometimes we see the face of the mom circled with a ghostly halo. There may be two rings of the pale light, one way outside the other. The circles may be incomplete, and there are times when the lunar halo is not a circle at all. The same kind of heavenly halos sometimes appear around the face of the sun.

Seen through a telescope, there is always a fuzzy halo around the golden face of the planet venus. From outer space, the earth, too, wears a halo of light at all times. These planetary halos are caused by sunlight dancing through the cloudy atmospheres of Earth and Venus. But the moon has no atmosphere. What's more, the lunar halo seems to be far, far above the surface of the moon near

Actually, a lunar halo is no where/the moon at all. It is no farther away from us than the top of the clouds. It is, in fact, caused by certain thin clouds which float perhaps five or six miles above the earth. These clouds are usually made from finest ice crystals. They may be dense enough to cast a milky glow over the sky, or they may be so thin that we do not see them at all.

However, these special clouds are always there between us and the moon when a Lunar halo appears. The icy crystals may be hexagonal fragments of plates and needles. It may take 50 or more of them to measure an inch. They are made of clear ice which glitters like glass, and as they drift and lazily turn through the upper air, they catch and refract the moonbeams like tiny prisms.

The lunar halo is caused by the bending or refraction of moonbeams as they filter down to us through the high flying clouds of ice crystals. As a rule, the halo takes the form of a circle about 40 times wider than the face of the moon. The light is most often ghostly white, but sometimes a lunar halo is tinged with rosy red on the inner side of the circle, fading to primrose yellow on the outer rim.

The drifting ice crystals sometimes bend the moonbeams at tricky angles, and the lunar halo becomes a geometric figure with sharp spikes and angles. Sometimes they do double duty and draw two circles around the face of the moon. The outer halo may be twice as wide as the smaller inside halo.

Halos of various types also occur around the sun, and. These, too, are formed by the same gauzy clouds of high flying ice crystals. They often occur on days when the sky is partly hidden behind a milky veil which hides the dazzling glow of the sun. The solar halo, of course, is caused by the refraction of sunbeams from the floating ice crystals.