Janet Henderson, age 12, of Lancaster, Pennsylvania, for her question:

Is Pluto really a planet?

Yes, little Pluto is a planet, paddling around near the outside edge of the solar system. Some people suggest that once upon a time Pluto was a moon that belonged to the planet Neptune. Or perhaps someday it will be captured by Neptune and become a moon again. These suggestions may prove to be true. Maybe Pluto was once a moon or maybe it will become a moon in the future.

But one thing is certain; at present little Pluto is a planet. We know this because a planet travels its own orbit around the sun. A moon swings around a parent planet and the two of them travel together around the sun. At present, Pluto is a planet because it travels a planetary orbit around the sun.