Tuesday, May 25, 2010

Chrysae, Tharsis and N. Lacus, May 22, 2010

Mars sketch
22 May 2010, 19:32 UT
200mm SCT f/10
422x, seeing 4/10, trans 3/5

Accepted as an Astronomical Sketch of the Day.

Mars' apparent diameter is now reduced to around 6", which is far from a maximum of 14" I have viewed and sketched last January. Still, 5 minutes of observation time in not so ideal atmospheric conditions (lots of air turbulence) and bright moonlight were enough to detect the main albedo features on the surface of Mars, currently residing in the constellation of Leo.

I didn't think it worthwhile to use colour filters due to the limited seeing conditions. However a light blue filter could have slightly enhanced the visibility of the features.

The much reduced north polar cap was seen as tiny bright patch adjacent to Niliacus Lacus. Underneath, the prominent Mare erythraeum was also visible.

No other subtle features were detected along the edge of M. erythraeum next to Chryse. Tharsis appeared bright.

After the session, I was pleased to note that the Calsky simulation confirmed the small features I saw through the scope. Mars images taken by the renowed planetary astrophotographer Damian Peach taken an hour later are here. These images, showing detailed albedo features were published on May 27th.


  1. Nice sketching, Charles,

    Almost looks like the real thing in colour. Well done.


  2. Hi Charles,

    We saw Mars last Friday from Bighi. Its orb was rather small but still can be made out. Power used was about 120x. We saw it from the new 8" Dobsonian by Skywatcher. Its optics are very good compared to its price. We even noticed peak of mountains on the moon on the dark terminator side and Saturn we could see the shadow of its rings on the planet's body. The trouble with Mars is that it is receeding so difficult to watch intersting features maybe the polar cap. We have just about a year and half for it to be starting growing again. Patience is a virtue.

    Keep on the good work of drawing the planets and the stellar systems.