I was driving across Indiana and Ohio yesterday when I asked myself a nerdy question: how fast would I have to drive to keep up with the Sun so that it was always at the same point in the sky? If you've ever been curious about this as well, keep reading; I'm about to figure it out.
The Data
First, we need to know two things:
- The circumference of the Earth
- The length of time it takes the sun to cover this distance
According to NASA, the circumference of Earth is 24901.55 miles, but we'll round up just to make things easy. As for the length of time that the Sun takes to go around the Earth, that should be obvious: 24 hours. Now we can figure out how fast the Sun is moving (apparently, mind you) around the Earth.
The Math
The equation for the velocity of an object is simple:
V = X / T
where X is the distance traveled in time T. Plugging in our data, we get this:
V = 24902 / 24 V = 1038
Thus, we would have to drive around the Earth at a speed of 1038 miles per hour if we wanted to "keep up with the Sun." As a reference point, the current land speed record for a wheel-driven vehicle is a paltry 458 miles per hour.
"The Blue Marble"
The "But"
You may have noticed that I used Earth's equatorial circumference, i.e. the distance around the equator. Odds are, though, that you aren't driving on the equator. So what about finding Earth's circumference at different latitudes?
The answer involves a bit of trigonometry, but to simplify, we can find the circumference of Earth at a given latitude using this equation:
CL = C × cos(L)
where C is the "true" circumference and L is the latitude. Since Columbus, OH sits at roughly 40° North latitude, we get:
CL = 24902 × cos(40) CL = 19076
Now plug this result into our original equation:
V = 19076 / 24 V = 795
So at 40° North latitude, I only have to drive 795 miles per hour to keep up with the Sun. (This is actually almost within reach of the current land speed record set by the ThrustSSC, a "car" powered by two jet engines.)
Hopefully the g-forces wouldn't keep me from texting all my friends!
Update: I made a spreadsheet in Google Docs that you can use to find your latitudinal circumference and required speed for following the Sun!
