Size of Sun as seen from Mercury |
Size of Sun as seen from Mercury |
Jun 20 2011, 03:02 PM
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#1
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Member Group: Members Posts: 656 Joined: 20-April 05 From: League City, Texas Member No.: 285 |
I got to wondering about this, considered making my own graphic, then googled and came up with the following, from Burton Mackenzie's blog:
http://1.bp.blogspot.com/_tlXkPX0vMqk/SaTW...ize_diagram.png So apparently the Sun appears about 3 times as large in Mercury's sky as it does on Earth. I was expecting something much more dramatic. |
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Jun 20 2011, 09:23 PM
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#2
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Solar System Cartographer Group: Members Posts: 10229 Joined: 5-April 05 From: Canada Member No.: 227 |
It's quite simple geometry. For the same object (like the moon), double the distance = half the size, half the distance = double the size and so on, and for different objects at the same distance, twice the size = twice the apparent diameter and so on.
So... for the sun, Mercury's a third of the distance that Earth is from the sun, so three times bigger is what you'd expect. Jupiter from Io? Jupiter is about 40 times the diameter of the Moon (very roughly) so from the Moon's distance it would look 40 times bigger than the Moon. Then multiply by the appropriate fraction for the ratio of distances - you can go from there yourself, I think. Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PDF: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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Jun 20 2011, 09:53 PM
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#3
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Member Group: Members Posts: 259 Joined: 23-January 05 From: Seattle, WA Member No.: 156 |
Bravo, Phil! That's much better than my answer - I was just going to say 2arctan(radius/distance), but your version's a lot easier to work out in one's head.
Apparent diameter in degrees (Moon from Earth = .5): Jupiter from Io 18.6 Jupiter from Europa 11.8 Jupiter from Ganymede 7.4 Jupiter from Callisto 4.2 |
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