The Earth is (Essentially) Still

Over dinner one time, I asked my daughter how fast the was earth moving.  At that moment, it certainly didn't feel to us as if the earth moved at all.  Instead of Googling the answer, we decided to apply what she had learned in math to figure out the orbiting speed of the earth.

First, we drew on a common formula to determine the circumference of a circle: C = 2πr (two times pi times radius).  The earth doesn't actually orbit in a perfect circle around the sun, but for the sake of this illustration let's assume that orbit is perfect.  Because we know the distance between the earth and the sun is approximately 93 million miles, we can plug this figure (radius) into the formula, and we get an orbiting distance of 558,000,000 miles. 

Second, we know that it takes 365 days for the earth to revolve completely around the sun, which translates to 8760 hours.  Using another formula that my daughter knew: distance = speed x time, we came up with a whopping orbiting speed of 64,000 MPH.   

We are literally hurtling in space at such a phenomenal speed, everyone of us!

(image credit)

By comparison, consider the following:

• A race car can travel 220 MPH
• A commercial airplane travels at 500 MPH
• The speed of sound is less than 800 MPH
• The turbojet Concorde flies at 1400 MPH
• An Apollo spacecraft travels at 25,000 MPH 

None of these come close to how fast we can move through space, simply by sitting at the dinner table.  By the way, Wikipedia notes that our orbiting speed is 67,000 MPH, even faster than what our rough calculation determined.

We got on this subject, I believe, because my daughter wondered why we had earthquakes, weather fronts, and wind, and I explained that in general it was because the earth was in constant motion.  There were also all sorts of pressure on and beneath the surface, and this energy contributed to natural phenomena and disasters. 

Yet, there is such stability and quiet to the earth's movement that none of us can feel a speed of 67,000 MPH.  More specifically, I think, the earth is hardwired in our mind and body as a fundamental frame of reference for motion.  It is as if we have habituated to that phenomenal speed, over generations and generations, because of that hardwiring.  I argue that what lends that unmistakable feeling of being still at the dinner table is habituation + reference.

Imagine hopping on any of the fast-moving vehicles above, and we immediately compare the ride to our frame of reference (speed zero, if you will), and we can easily feel the motion and speed.