Mars- Catch It Now
If you haven’t seen Mars yet this year, now is the time to check it out. This is the best Mars apparition since 2007, but the Earth passed Mars last month and we are pulling away from the red planet as we go around the Sun. Although Mars was at its closest last month, good, detailed telescopic views are still to be had if you act soon. Mars remains over 10 arcseconds in size- good enough for fine visual observation- in May and through nearly all of June. After that, larger telescopes will generally be required and CCD photography will be needed to resolve more than the very largest details on the Martian surface.
My first telescopic view of Mars this apparition was in early April, when Mars was at opposition. I could see Mars’ north polar cap (“NPC”), but the seeing was so poor I couldn’t see anything else clearly enough to draw and record my observation. My first good view was in late April when Mars’ disk was still as large as 15 arcseconds. The drawing below shows the eyepiece view I had in my Celestron 11” Schmidt-Cassegrain telescope. I took the accompanying photo a bit over one hour later when Mars had rotated around another 15⁰ in longitude.
The technical details are listed below each image. On the left side (the Martian east or preceding side of rotation) of each picture is the long, dark pointing finger of Mars’ most prominent visual feature, Syrtis Major. Syrtis Major is a very ancient, heavily cratered, low relief volcanic shield. Its dark color is from basaltic rock which is regularly scoured of orange Martian dust by wind. Syrtis Major is also an area from which spacecraft sensors have detected emissions of methane gas. Above (south) of Syrtis Major on the south preceding limb is the circular, cloud-filled Hellas basin. Hellas was formed by an ancient asteroid impact and is over 1,300 miles in diameter and is as much as 6 to 7 miles deep (the Grand Canyon on Earth is only 1 mile deep). Powerful Martian dust storms often start here. The long, dark horizontal feature in the upper middle of the disk is Sabaeus Sinus, which also runs about 1,300 miles to connect with another dark feature, Meridiani Sinus. Meridiani Sinus is the current residence of the Opportunity rover. It is about 400 miles wide (about the distance from Washington D.C. to Boston) and has periodically been covered by water in Mars’ distant past. Hematite, a mineral normally produced in water, was found here by space probes, including Opportunity. The dark feature to the lower left (north preceding) of the disk is the Utopia plain, site of the Viking 2 lander in 1976. In the photo, Utopia has largely rotated out of view while the Acidalia plain rotates on stage. The Acidalia plain is a low, flat area approximately 1,600 miles across and about 2 miles below the average elevation of the Martian surface (the “datum”). The following side of Acidalia is partially obscured by clouds. This plain is considered to be more geologically recent than the higher, heavily cratered terrain in the southern hemisphere and is believed to be part of the bed of an ancient Martian sea. This theoretical sea is thought to have existed earlier in Mars’ history when its atmosphere was thicker and warmer and could have supported liquid water on the surface.
My next two Mars observations were taken in early May. As you can see from the technical information below the images, Mars was still a decent size for visual observing and remains so as this is written.
In the left image above, Syrtis Major and Utopia were on the west, or following side of Mars. To the left of Utopia was a small, somewhat dark marking called Nodus Alcyonius. It is the remnant of what was Thoth-Nepenthes, a prominent, curved dark feature that connected Utopia with Syrtis Major and largely vanished in the second half of the 20th century. Elysium Mons (mountain) lies between two somewhat linear grayish features. While not part of the collection of giant volcanoes on Mars’ Tharsis bulge, Elysium is the third largest mountain on Mars and among the 10 highest in our solar system. Elysium is 46,000 feet above the surrounding lava plain and 52,000 feet above the Martian datum. The caldera on top of this volcano is 8.7 miles wide and the base of the mountain is 150 miles across. Elysium often appears as a bright, white spot when it is covered by the flat “orographic” clouds that frequently float over mountain tops…including those of high mountains here on Earth. The image on the right shows a tiny bright spot on the edge of the disk following the NPC. This bright spot may have been part of a cloud or a patch of frost. The large, dark feature in the south is the heavily cratered Cimmerium region extending some 3,400 miles in Mars’ southern highlands. The bright rim on the preceding side of the disk indicates clouds that were easier to see in a blue filter.
I’m looking forward to the current rains leaving us very soon so that I can get out again to continue observing Mars. The view changes as Mars rotates at almost the same rate as we do on Earth. Now is the time to explore Mars for ourselves. If we do not act during this brief window, we’ll have to wait two years for our next good opportunity.
Jay Albert, May 15, 2014