Mars begins its retreat
Over the past couple of weeks, I spent more time trying to get images of Mars during its current apparition. Snowy weather and poor atmospheric conditions presented some challenges. But, I finally managed to make a decent capture last week. Compared to the image I made in late January, last week’s image already shows the disc of the planet has decreased in size and shadow is creeping in on the following, or morning, side of Mars. As Mars gradually becomes more distant, the shadow will appear to grow as the sunlit parts of Mars are seen by Earthbound observers at an increasingly oblique angle.
February 17th, 2010
In addition to the differences mentioned above, more easily distinguished surface features are visible. The northern polar cap remains prominent, but will shrink down over the coming weeks as summer arrives to the Martian northern hemisphere. The feature that looks a bit like the Indian subcontinent is called Syrtis Major. The long armed feature pointing across the bottom left is Sinus Sabeus. The lobe at its end is called Sinus Meridiani. That is where the Mars rover Opportunity is trundling around the surface. My January 31st shot had more a precise focus, but it holds less visual interest with regard to surface markings.
I used the same telescope and camera set-up to make this most recent Mars image. To get a sense of how things have changed over the past weeks, I made an alternating image to blink compare the two shots. Click on the image below to see the difference.
Mars - January 31st, 2010 vs. February 17th, 2010
