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?
Quote:
Originally Posted by astro744
"The observation of planets is a delicate art." M. du Martheray.
(As quoted in Introduction to Observing and Photographing the Solar System by Dobbins, Parker, Capen, Willmann-Bell publisher).
At 240x an object 15 arc seconds will be 1 degree in diameter.
i.e. 15 x 240 = 3600 arc sec = 1 deg.
The Moon is 1/2 degree in diameter.
Try the following next full moon which happens to be an eclipse so it will look reddish like Mars:
Look at the Moon unaided and see what features you can see. Try and sketch light and dark features to scale. If you can do this with a 1/2 degree object then Mars at 240x will be no problem.
Use filters; Red, Orange, Yellow, Green, Blue & Violet all give different views.
The art of observing is being able to detect small low contrast detail. Filters help bring out such detail but a trained eye will begin to detect such detail without filters.
Back in the days of film a visual image was always better than the photograph because your eye sees brief very steady views amongst prolonged periods of not so steady views due to our atmosphere. Film used to record the not so steady moments during the few second exposures. Nowadays video recordings capture the view and then only the good frames are selected and combined to form views that are better than any large ground based telescope in the days of film could ever have recorded.
You will not see Mars in the telescope as you do in some of the recent pictures being posted. However, you can still detect many markings on the planet that really stand out including the poles, Syrtis Major, Hellas Planitia, Sinus Sabaeus, Sinus Meridiani and Solis Lacus to name a few. The latter is also known as the Eye of Mars and is my personal favourite since it is small and not always easily detectable.
Note too Mars has dust storms that can engulf the entire planet and then no features are visible although such large storms are rare. Often smaller dust storms are seen covering some features.
Find yourself an observing guide to Mars for this opposition showing a map of the entire planet and a table showing the longitude of the central meridian for any given night. Mars spins 24h 40m so the same feature will be on the central meridian 40 minutes later each night.
There is plenty of info at http://alpo-astronomy.org/
Enjoy! |