Double your Moon pleasure

Double your Moon pleasure

Double your Moon pleasure

Bad Astronomy
The entire universe in blog form
March 29 2007 7:33 PM

Double your Moon pleasure

This seems appropriate to post now, since I'm on the East coast giving my Moon hoax talk at New England College in New Hampshire and the St. Andrews school in Delaware.

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!  

It's been claimed that if you speed up Apollo footage of the astronauts on the Moon by two times, it looks like they are moving normally. This must mean that NASA filmed them in a studio, and simply slowed down the video by a factor of two to make it seem like lighter gravity.


Brilliant! Except for one problem: it doesn't work.

First off, slowing the film by a factor of two is wrong. The time it takes for objects to fall depends on the local gravity: in fact, on the square root of the local gravity. Since the Moon has 1/6 the gravity of Earth, things take 61/2 or about 2.45 times longer. Doubling is close, but not quite right. For those doing the math at home, remember that the distance an object falls equals 1/2 a t2 (from Newton; a = acceleration due to gravity and t = time). Solve for t. Voila.

Another problem is that this only works for things falling under gravity. The motion of the astronauts' arms, legs, etc. still look normal when viewed at normal speed. When doubled, the astronauts' movements look cartoonish. You can see this for yourself on a YouTube clip someone kindly posted:

See how silly this is? Mind you, Joe Rogan used this as support of hoaxery when we debated on Penn's show. I told him he was wrong, and he said he was right. You be the judge.

But I'm right and he's wrong.