measuring the sky

frith cued me in to the Geminid meteor showers which are peaking tonight. Here, clouds rolled in and we're getting light rain showers instead. But if any of you have clear skies, you might still be able to see them.

I found this very handy page that shows how you can estimate angular distances in the sky using your hands:
A Handy Guide to Measuring the Sky

Making a fist and twisting it left and right to count how many times it takes to span half the room around me, the guide does seem to estimate it pretty well. (half way around the room = 180 degrees = about 18 fist widths).

HOWEVER. The guide also says that the full moon is 30' wide, which if I'm reading it right means that the moon would be only half a pinky finger's width wide, when holding your hand out at arm's length. NO WAY. I know the full moon changes size as it moves through the sky, even though it doesn't. But still, only half a pinky's width?? Even at its smallest, I'd never think it was that small... Now I have to wait til the next full moon to see if that can possibly really be true.


astronomers measure the distance between celestial objects based on the angle they make with an observational point on Earth. Known as angular distances or angular separation, distances are expressed in terms of degrees (°), arc minutes ('), and arc seconds (").
...
There are 360° in a circle or sphere, each degree is divided into 60' and each arc minute is further divided into 60".
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Your little finger at an arms length is about 1° wide.
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The angular diameter of a full Moon is about 30'...

..

Hey, but, however:
The main reason I was reading about that was to see if my estimate of how far apart Jupiter and Saturn were tonight was correct.

According to theskylive.com's quick hilights for today: Jupiter and Saturn are in conjunction with an apparent angular separation of 0° 50’ 21”, currently decreasing.

So if the moon is 30', then Jupiter and Saturn *are* between one and two full moon widths apart, and my estimate WAS spot on. Yay me.