Stephen Lowe, age 12, of Vancouver, B.C., Can., for his question:

WILL NEPTUNE EVER HIT PLUTO?

Neptune and Pluto, as we know, are the two outer planets of our sprawling solar system. Most of the time, little Pluto pedals around the outside edge. But its orbit is quite oval and part of it swings inside the orbit of Neptune. It takes 248 earth years to complete its orbit and its distance from the sun varies from 2,766 million miles to 4,567 million miles.

In 1969, Pluto reached the part of its orbit which is about 3 million miles closer to the sun than Neptune. Until the year 2009, Neptune, and not Pluto, will mark the outer edge of the solar system. But astronomers assure us there is no danger of a collision between the two planets. For one thing, Pluto's orbit is tilted at a steep angle. What's more, even if Pluto did happen to come too close, the gravity of Neptune would capture it and send it around as an orbiting moon.