From StarDate Online-- great site.
How fast is Earth moving through space?
To begin with, Earth is rotating on its axis at the familiar rate of one revolution per day. For those of us living at Earth's midlatitudes -- including the United States, Europe, and Japan -- the rate is almost a thousand miles an hour. The rate is higher at the equator and lower at the poles. In addition to this daily rotation, Earth orbits the Sun at an average speed of 67,000 mph, or 18.5 miles a second.
Perhaps that seems a bit sluggish -- after all, Mars Pathfinder journeyed to Mars at nearly 75,000 miles per hour. Buckle your seat belts, friends. The Sun, Earth, and the entire solar system also are in motion, orbiting the center of the Milky Way at a blazing 140 miles a second. Even at this great speed, though, our planetary neighborhood still takes about 200 million years to make one complete orbit -- a testament to the vast size of our home galaxy.
Dizzy yet? Well hold on. The Milky Way itself is moving through the vastness of intergalactic space. Our galaxy belongs to a cluster of nearby galaxies, the Local Group, and together we are easing toward the center of our cluster at a leisurely 25 miles a second.
If all this isn't enough to make you feel you deserve an intergalactic speeding ticket, consider that we, along with our cousins in the Local Group, are hurtling at a truly astonishing 375 miles a second toward the Virgo Cluster, an enormous collection of galaxies some 45 million light-years away.