Spilhaus Clock

My astro club meeting was around a month ago, but still, I wanted to show you something cool. It is called a Spilhaus clock. It shows everything! It was made by a man named Athelstan Spilhaus. He is an oceanographer, geophysicist, and an inventor of sorts.

Here is how it looks like:

The clock has the following features:

1. The horizon and the Visible Heavens 
2. Sun Position in the Sky. 
3. Moon’s Position 
4. Position of the Stars 
5. Relative Position of Sun, Moon and Stars 
6. Day of Month and Year … a Perpetual Calendar 
7. Solar Time of Sun, Moon and Stars at Meridian 
8. Sidereal or Star Time. *
9. Current Phase of the Moon 
10. Time of Daily Sunrise and Sunset 
11. Mean Time of Moon Rise and Moon Set 
12. Mean Time of Star Rise and Star Set 
13. Current Time High or Low Tide 
14. Current Stage of the Tide 
15. Mean Solar Time** This clock is in

This one shows regular time.

Finally, this one shows the various times in various time zones.

Cool, eh?

*Solar time is the time it takes for the sun to be in the same position in the sky, exactly 24 hours.

**Sidereal time is the time it takes for the stars in the sky to return to the same position in the sky, which is 23 hours, 56 minutes. Yes, that is right, solar and sidereal time are different. In fact, the sidereal time is more of a “real time” because that is when Earth turns exactly 180 degrees, while in solar time, to keep up to the sun, the Earth has to turn a few degrees more.

File:Sidereal day (prograde).png

Note how position 2 is when the Earth turns exactly 180 degrees in the orbit from position 1 to 2. Say in part number one, you are in a sunrise, then in part two, it still hasn’t risen yet because the Earth has to turn a bit more (part 3) so that the sun rises to the exact place as it was in position 1. See? Not that hard. ^_^ Unless I suck explaining things. So yes, if you have a question, you can comment on it.


2 Responses to Spilhaus Clock

  1. Jim says:

    I teach astronomy at Rowan University. I have found two of these clocks for sale, ranging in price from $750 up to around $950. Both are in very good condition. Beings that you’ve just recently purchased one, does this sound like a reasonable price?

  2. ibyea says:

    I didn’t buy one, I was just showing something interesting. I know a guy in my astronomy club, though, who bought it in e-bay for 200-250 dollars just because someone called it a “space clock” instead of a “Spilhaus Space Clock.” And yes, most people sell it in those ranges of prices, they are very expensive.

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