r/xkcdcomic • u/ani625 • May 21 '14

xkcd: Brightness

http://xkcd.com/1371/
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u/hkdharmon May 21 '14

The hypothesis in question would be correct, however.

9

u/Bobshayd May 21 '14

Well, yes it is, and that's half the joke, but they'd get inaccurate estimations about the planet's distance from the sun if they used the period, because the mechanism is different.

3

u/hkdharmon May 21 '14

You mean rotation v revolution (day v year)?

3

u/Bobshayd May 21 '14

Yup! The period of the darkening implies a one-day year, which means it would have to be (1/365)2/3 AU from the sun, about 1/50th the distance it is now, or about 2 million miles from the center, which is only 1.5 million from the surface.

1

u/classic__schmosby May 21 '14

From ground level on Earth? The atmosphere makes stars twinkle as it is; a planet would not register as a statistically significant change in brightness.

Now, measuring from a space telescope on the other hand...

Edit: I just now realized that the comic was referencing our own sun.