The best bang since the big one

The best bang since the big one

The best bang since the big one

Bad Astronomy
The entire universe in blog form
June 9 2007 9:25 AM

The best bang since the big one

The obvious line is, "Did the Earth move for you"?

The correct answer is, "Yes. A lot."

Phil Plait Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  

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My old friend and evil twin Richard Wiseman came up with a funny idea: if you were to add up all the motions of the Earth over a given period of time, how far would it have moved?

Lessee: it spins at 1000 mph at the Equator (don't forget to compensate for latitude), it orbits the Sun at 18 miles per second, the Sun orbits the Galactic center at about 200 mps, and the Galaxy is moving toward th Andromeda Galaxy while simultaneously falling into a massive cluster of galaxies called The Great Attractor. Oh -- the Universe is expanding, with the visible edge receding from us (or equally, we are receding from it) at the speed of light.

So if you take some given amount of time, you can calculate how far you moved during that time.

Still, that's a bit dry. How to make this exciting to the average person?

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Why, create a website that calculates how far you traveled during sex, of course!

So he did: Behold EarthMove.info, where you can enter your city and the length of time it took you to, ah, well, trip the sheets fantastic. It will spit back at you the distance traveled during that time.

This is a pretty funny idea. Richard actually approached me about it months ago, but somewhere down the line I think I dropped the ball (a bit of calculus interruptus, I'm afraid), so he went to Scotland's Astronomer Royal John Brown, who I suppose knows a thing or two about galactic motions.

There are some caveats: the velocities are not treated as vectors, so this is an upper limit to how far you moved; if, for example, the Earth is spinning in the opposite direction of the motion of its travel around the Sun (that is, you were getting some afternoon delight) then the distance traveled is slightly less.

Also, if you think about it, the biggest source or motion here is the expansion of the Universe. That's the speed of light, and all the other velocities are small compared to that, so it dominates. Your latitude hardly matters at all.

Some people will probably be offended buy this, but it's really just a fun way to get people to think about astronomy and science, so of course I stand behind it.

Tip o' the... well, something... to Teek.