Expert: Ed - 1/18/2009

Question
what caused the sun to be tilted at 7.25 degrees?

Answer
Joe, when the primordial nebula coalesced into our solar system, some of the whorls and eddies of rotation had slight irregularities, perhaps due to relatively minor imbalances of mass within the early structures which eventually became our sun and planets.  They continue to this day, and the sun's slight obliquity is one of these irregularities.

The planets are not all exactly on the ecliptic, as you might have noticed.  They're pretty close, but it isn't an exact match.  It's just because the early solar system was an incredibly violent, chaotic place, with lots of irregularities keeping things out of whack.  We're just lucky things managed to get as stable as they are, otherwise life would never have had a chance to do as well as it has on our planet.

Keep Looking Up,
-Ed