All the planets have an inclination of equator to orbit. As you probably know, the planets orbit around the sun in more or less the same plane. Except for Pluto, it is believed they were all formed at about the same time from a huge cloud of dust and gas about 5 billion years ago.

Because they all formed from the same cloud, it makes sense that they would all spin the same way and with no inclination of the equator to orbit. Something must have forced the planets to tilt.

It is likely that one or more large collisions with other bodies in the solar system made the planets tilt. We know that all of the planets have had numerous collisions because of the craters that we can see on them. Every time something hits a planet, it will tilt it a little bit. If it hits near the top or the bottom of the planet it will have a larger tilting affect.

Here is a table showing what the inclinations of equator to orbit are, in degrees, for some of the planets.

Notice that poor old Uranus is almost lying on it's side. It must have really been hit hard.

By the way, if the Earth wasn't tilted, we wouldn't have four seasons.

Thanks for your question, the first one for 1996/97

Answer #% % filename B001.DOC page% % page 1 of% % numpages 1 % % date \@ "MMMM d, yyyy"November 7, 1996

��|Brian Oderkirk, room , Julie Breeze