The sun's location in the Milky Way. The angles represent longitudes in the galactic coordinate system. Credit: PD-USGov-NASA.

From far away, at the right angle, the Milky Way resembles an uneven pancake with a bulge at the center. But it's quite a big pancake, more than 100,000 light-years in diameter and about 3,000 light-years thick through the middle. The sun is 26,000 light-years from the center (in this part of the galaxy, that's about two-thirds of the way out).

The stars in our galaxy orbit the galactic core in much the same way the planets move around the sun, except the stars also ride gently up and down like horses on a merry-go-round. The sun, moving at 250 kilometers (155 miles) per second, takes 220 million years to make one trip around the center. The sun, and hence our solar system, has made fewer than 25 such journeys since its birth.