Quote:
Originally Posted by -George-
Hi, If I may ask...
The moon is 1/2 degree in diameter looking at it with your eyes. That means mars through the telescope at 1 degree should look like 2 moon sizes by eye - no scope.
A moon generally looks big at night... if mars is 2x the size of that (1 degree vs 1/2) then Mars should look absolute huge. I am confused on this degree business.
And when is the moon 1/2 degree because some nights it looks as big as the sun. So what is all this degree based on and why isn't mars double the size of a big moon since its 1 degree not half?
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The moon looking big is an optical illusion brought about by foreground objects. Notice how the moon looks bigger at the horizon than it does at the zenith. But it's not. You can prove this by sighting the moon through a long thin pipe, or a telescope with micrometer eyepiece, although the moon is slightly "flattened" very near to the horizon. Mars through the eyepiece has no foreground objects to give it size perspective.
The "apparent" size of the moon just happens to be the same "apparent" size of the Sun, most of the time. There is some slight variation due to apogee and perigee but roughly they are both about 30 minutes of arc apparent diameter.
Degrees are easy to understand. They are much like time. 60 arc seconds = 1 arc minute. 60 arc minutes = 1 degree. There's 360 degrees of azimuth. It would take 720 moons or suns end to end to go around the horizon. In R. A. 15 degrees = 1 hour. It takes 24 hours to rotate 360 degrees (24 x 15 = 360)
I have a similar telescope to you, a 10 inch f4.5 Newtonian (and a few others). As others mentioned, Visually, Mars is very demanding on perfect conditions and perfect collimation. Most of the time all I see is a red dot and maybe an icecap. Many amateurs are very skilled these days at producing amazing images that rival professional photos of only a few years ago. If you want the "eye" view, it would be comparable to one sub out of the hundreds or thousands of subs that are used.
Edit, beaten by Julian as typing with a kitten on lap is slow work lol.