Last Sunday night we had some clear but very cold weather. I had been thinking for a while that I ought to get my Maksutov-Cassegrain out to have a look at Mars as it is so high up in the sky at the moment. Rather than spend an hour trying to set the telescope up properly I just decided to use the hand controller to keep Mars in view. This is what I had been doing with my Venus observations and it is so much quicker to get going. It is just as well because only ten minutes after I had started everything froze up (including the correcting objective lens)!
My main priority was to do a drawing of Mars rather than try to photograph it. I looked out some coloured pencils before I started and chose those which I thought would match the colours I was expecting. It was still quite a difficult thing to do. Fortunately, I worked out that I could perch on some step ladders next to the telescope so I could draw and look down the eyepiece at the same time. Holding a torch, a notebook and various pencils whilst the air temperature was below freezing is no easy task. However, I succeeded and here is the page out of my notebook:-
Mars reached opposition on January 16th and it has now moved away from us decreasing in size from about 14.6 arc seconds to 13.6. Its phase has correspondingly reduced but at 99% this was hardly noticeable. My Orion OMC 140 has a focal length of 2 metres which together with a 9mm eyepiece gives a magnification of about 222x. Even at this magnification Mars appears to be pretty small! I did try and include a x2 Barlow lens but this didn't really improve matters and it seemed that a brighter image at 222x was a better option.
The main features to be seen were the northern polar cap (which was delineated by a dark area close to its southern edge) and a large area of darker colour to the south. Not knowing exactly what I was looking at I have found a useful tool produced by Sky and Telescope - this is their Mars profiler. You can use the tool to set the date and time of your observation and to choose what telescope set-up you have. Using the date and time of 2nd February 2025 at 19:15 UT and Mirror Reversed (I was using a Maksutov-Cassegrain with a star diagonal) you get a projected map of what I was looking at. Unfortunately, it doesn't show it as a sphere so features at the edge of the map will appear foreshortened.
What I saw does sort of match up with this projected map. The central red circle on the map is the part of Mars that points directly at Earth and this is placed over an apparently featureless red area called Tharsis which is actually a vast volcanic plateau which is home to the largest volcanoes in the solar system. With more resolution it would be possible to see white clouds associated with the tops of these mountains. The darker area to the south of Tharsis is probably Solis Lacus and shows up well on my drawing. To the left and right of this are other dark areas of Mare Erythraeum and Mare Sirenum. There is a bit of a gap between these dark areas and another dark area hinted in my drawing called Niliacus Lacus. It is to the far left of my drawing. The gap is called Chryse Planitia.
For a further explanation of the Mars profiler look at this article in Sky and Telescope. Note that the profiler also gives the position angle (PA) of the north pole and the central-meridian longitude (CM) which for my observation were 345 and 89 degrees respectively. The PA is measured from North through East and explains why the northern polar cap appears to be tilted 15 degrees westwards in my drawing. The CM is a longitude measurement on Mars and shows which longitude is pointing directly at Earth.
All text and images © Duncan Hale-Sutton 2025
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