Dana Zahranchek, age 13, of Winnipeg 14, Manitoba, Canada, for her question:

Will the earth's axis shift any more?

In a general way, we can assume that the two ends of the earth's axis continue to point to more or less the same two opposite points in the heavens. However, our dizzy planet performs a variety of motions, and no celestial motion is absolutely precise. The pull of the sun and the moon create tidal imbalances and slight shifts in the axis. A strange motion called precession is caused mainly by the orbiting moon's path above and below the bulging equator. The sun and moon also cause a very tiny axis variation called nutation..

In the precession motion, the North Pole end of the axis describes a small, slow, circular motion. This is continuous and each circle takes 26,000 years. During this period, the North Pole points around a select circle of North Pole Stars. In the motion of nutation, the axis makes a nod of about one 400th part of a degree. This is related to repeated variations in the moon's orbit and each mini nod takes 18.6 years.