How far we have come!

Because we are nearing the end of another trip around the sun, I thought it might be interesting to determine just how far we earthlings travel in a year.

Everything I say after this is approximately true but not necessarily specifically accurate because I will be dealing in generalities.

What are we, 93,000,000 miles from the sun? We will use that as the radius of the great more-or-less circle of Earth's orbit around Old Sol. Then, using either the formula 2(pi)r or (pi)d where (pi) = 3.14159 and r = 93,000,000 and d = 186,000,000 (because diameter, as we all should know, equals 2 times radius), we come up with the answer that the circumference of the great more-or-less circle that is Earth's orbit around the sun is 584,335,740 miles.

The kids in the back seat are asking, "Are we there yet?"

No, we are not.

So far we have determined our forward motion around the sun in one year. But even though our planet is moving forward through space in its orbit 1,599,824 miles every single day (which figure I obtained by dividing 584,335,740 by 365.25 —- the number of days in a year), that is not our only movement. Our home planet also spins on its axis once every day. A person standing at the equator would travel 25,000 miles a day even if he or she is standing still. Let's add that distance into our calculations. When we multiply 25,000 miles a day times 365.25 days we discover that the person standing still at the equator has travelled an additional 9,131,250 miles during a year.

The final step is to add the forward motion and the spinning motion together. Let's do that.

584,335,740 miles moving forward in our orbit plus 9,131,250 miles spinning every single day on our axis gives us -- drum roll, please —- TAH-DAH!

593,466,990 miles !!!

Here's a caveat. A person standing at the North Pole or South Pole will not travel 25,000 miles every day, just perform a piroutte, as it were. So subtract the 9,131.250 miles for him or her. People at various latitudes travel somewhere between a pirouette and 25,000 miles each day. For each degree of latitude, for each minute of each degree of latitude, the distance varies. I'll let you figure out your personal distance on your own.

Good luck.

Nobody said it was going to be easy.

Here's another caveat. In the olden days, we were all taught that the earth's diameter is about 8,000 miles and the earth's circumference is about 25,000 miles, and those are the figures I used in this post. But they are not correct. According to the website space.com, NASA's Goddard Space Flight Center says that the radius of Earth at the equator is 3,963 miles (6,378 kilometers). However, Earth is not quite a sphere. The planet's rotation causes it to bulge at the equator. Earth's polar radius is 3,950 miles (6,356 km) — a difference of 13 miles (22 km). Using those measurements, the equatorial circumference of Earth is about 24,901 miles (40,075 km). However, from pole-to-pole — the meridianal circumference — Earth is only 24,860 miles (40,008 km) around. This shape, caused by the flattening at the poles, is called an oblate spheroid.

You may wish to re-calculae the numbers on your own to get a more accurate answer.

Here is the Earth as seen from Apollo 17 in 1972:

We've come a long way, baby.