How fast are we going?

This sounds like a stupid question because unless we walk or drive a car, we’re standing still.

Right?

Wait, that’s not true in the absolute sense. Yes, when we’re standing still, we’re not moving at all relative to the Earth. But, Earth is certainly not standing still. Let me count the ways . . .

We’ll start with the Earth’s rotation, which is once every 24 hours relative to the sun and 23 hours 58 minutes and 4 seconds relative to the stars. Close enough! What one has to do is determine the angular speed. For the sake of simplicity, we’ll say that the Earth rotates 360 degrees (7.29 times 10 to -5 radians per second) every 24 hours. Multiplying this by the Earth’s equatorial radius of 6,378,137 meters gives us an equatorial speed of 465.1 meters per second. Remember that a meter is equal to 3.28 feet. So, we are traveling 1,525.5 feet per second, which is 508 yards per second or around five football fields every second. That’s faster than my car!

The Earth is roughly 93 million miles away from the sun and it takes 365 days to orbit our star. At this distance, the Earth is moving 67,000 miles per hour. Now, that’s moving!

But wait! The sun, along with the solar system, is orbiting the center of the Milky Way galaxy. The sun is around 28, 000 light years from the center and it takes about 200 million years to orbit around the galaxy’s center, which works out to roughly 230 kilometers per second. I hope there are no galactic cops out there.

But wait! The Milky Way galaxy is moving around in space. Here’s where it gets crazy. One has to define the movement of the galaxy relative to something else. If we pick on the Andromeda galaxy, the Milky Way galaxy is closing with it’s neighbor in the Local Group at 130 kilometers per second and in a few billion years we’re in for an gigantic collision that will change both galaxies forever. We’ll become a big elliptical galaxy instead of the nice spiral galaxies we are now.

For extra credit you could calculate all of the movement vectors and combine them to find a composite vector relative to the center of the galaxy. The Galactic Coordinates of Earth are based on the galactic plane of the Milky Way galaxy. The galactic latitude and longitude are referenced to this plane that runs though the galaxy. For example galactic center or zero degrees longitude is at Sagittarius. Galactic North is plus 90 degrees at Coma Berenices. You would have to use polar coordinates to add the vectors. The problem is that the final vector for you standing on the Earth would be constantly changing.

Or you could just guess. The truth is that we are not standing still. We’re kicking it at some bodacious speed. I wonder who’s driving this accident looking for a happening?

Thanks for reading.