The planet Mars roars into October rising in the early evening with a 22.5" disk and 99% illuminated at -2.5 magnitude. Mars appears after Saturn and Jupiter are in the western sky and Venus doesn't rise until 8 hours later. Mars loves to show off when the other bright planets aren't looking. It crosses high in the northern sky, and beams brightly at midnight--finally ruling the night. Although the red planet will never outshine Venus, Jupiter has been bested. At least for a couple of months!

Our closest approach to the red planet occurs on October 6, 2020 when Mars will be 38,568,243 miles or 62,069,571 km away from Earth. Opposition occurs at 23:20 UT on October 13, 2020. Don't miss out on this apparition because Mars will be farther away from Earth for the next opposition on December 8, 2022. For the 2022 opposition, the disk of Mars will be only 17.2” - - smaller than Mars' disk at the beginning of September this year.

Not including planet Earth, no planet ignites my imagination like Mars. Its periodic oppositions always capture my interest and today we know more about Mars than ever thanks to a flotilla of space probes that have orbited and landed on the surface. Unquestionably, the best time to see Mars is when Mars is opposite from the Sun in Earth's sky. Oppositions occur 2 years and 2 months apart in general, that's when amateur astronomers, astrophotographers, and space-faring nations concentrate their attention on Mars.

This opposition, Mark Schmidt of Racine County in Wisconsin was kind enough to allow his image to be used on Astra's Stargate. Mark used his 14" Schmidt Cassegrain telescope to take this image on the night of September 23, 2020 at 6:27UT. On this image, an albedo feature on Mars known as Solis Lacus, for "Lake of the Sun" is on the central meridian (CM) of Mars. Astronomers use the CM to designate exactly what part of Mars is visible on the disk. South is up on the image as Mark's instrument has inverted the image. Mars is rotating from right to left in this image, with the left edge preceding and the right edge following. The disk is rotated 25.2 deg. because of the axial tilt of Mars. The southern polar cap has been shrinking as the southern hemisphere has turned toward the Sun. The northern solar cap is at the bottom of the image. This disk of Mars is 97% illuminated.

You won't find Solis Lacus marked on a modern Mars map because it was discovered by the early observers who used telescopes. It was first drawn in 1704 by Jacques Maraldi and named by Giovanni Schiaparelli in 1877. Light and dark features on Mars due to reflected light from the Sun are called "albedo features". Details that can be seen on the planet Mars with Earth-based telescopes only allow the rough features of the planets surface to be resolved. It wasn't until Mars Viking and other space probes visited the red planet that detailed features on Mars could be identified. Solis Lacus is also known as the "Eye of Mars" or the "Black Eye of Mars". Amateur astronomers look for it during oppositions.

Today, surface features making up the Solis Lacus area are Syria Planum, Sinai Planum, Thuamasia Planum and Solis Planum, with other surrounding features as well. Valles Marineris forms the northern boundary and Mark's image shows us why astronomers were so surprised that the "Grand Canyon" of Mars was a giant scar on the surface of Mars. Solis Lacus is perhaps the most changeable feature on the planet. Giant dust storms have been observed to originate in this ares. They may encompass most of the southern hemisphere and have a global impact on the planet. Even dust devils have been observed in Solis Lacus. Most of this area is very dusty. With Valles Marineris in the picture, there is no doubt that this a geologically active area and Syria Planum has been found to contain many small shield volcanoes. Speaking of volcanoes, in the lower right quadrant of Mars in Mark's image, the brightest splotches are volcanoes on Tharis Ridge, including Mount Olympus and my favorite, Alba Patera. They may be hard to see if you are not used to looking at Mars images in small telescopes.

I always wanted to see the "Black Eye of Mars" in my 6" telescope, but every time I was observing, Solus Lacus was out of sight or covered with dust. This year I was able to see the Solis Lacus area in my telescope and I attempted to make some sketches of it at the telescope. I would like to present this drawing of Solis Lacus, not drawn at the 'scope but actually the next morning. The features popped in and out as I observed but I wanted to present a drawing of Mars as it is seen through a small telescope. The lightly drawn features show how difficult it is to see Mars in a small telescope. This would be how Mars appears in my telescope at about 250x magnification on a fair seeing night--though not great. This year's wild fires in California impacted the viewing of Mars features for many observers. The scan of my paper seems to give Mars a bit of a bluish cast that is not seen through the scope but may be noticed here. For the 2018 opposition, the What's Up almanac featured an article on drawing Mars.

Visually, at the telescope, Mars surface appears a pale orange color. Look at Mars in the sky around opposition and it will probably appear orange to you, even though it is called the "red" planet. In the past, the dark markings on the surface appeared brownish to me but this opposition the dark markings appear grayish - - not brown or black. The northern polar cap (or more likely, the north polar hood) at the bottom of the drawing seemed easier to see when Mars' CM was closer to 30-deg. but I am not sure. Before the Eye of Mars approaches the center of the disk, the right quadrant seems plain compared to the rest of the surface. This part of Mars has been covered with volcanic flows from the huge volcanoes of Tharsis. Amateurs with larger instruments and cameras have spotted clouds on the summit of Olympus Mons. This opposition was a lot more favorable to the northern observers than the closer opposition of 2018 when Mars was low on the horizon.

For more information on oppositions of Mars, check out Astra's Mars Oppositions and the Mars Opposition 2020 pages.

The Great Conjunction

Jupiter and Saturn orbit closer toward their great conjunction when Jupiter overtakes the ringed planet, and the two outer gas giants appear very close together in Earth's sky. This generation's great conjunction occurs on December 21, 2020, the date of Earth's winter solstice when the sun hits the southernmost point in the sky. (The Sun appears to stop or stand above the horizon at the exact same place while Earth's orbit causes it to "turn" and travel toward the north.) We are extremely lucky because this year's conjunction will be seen when Jupiter and Saturn are over the horizon. This was not the case for the 2000 great conjunction. That slipped by without much ado because it couldn't be observed.

Jupiter and Saturn have spent most of 2020 in the eastern side of Sagittarius but last month both planets reached their stationary points and now are continuing in their usual prograde direction. By December 18, both Saturn and Jupiter will have cross into the constellation of Capricornus, and so the actual Earth-based moment of conjunction will occur on the far western edge of that constellation.

What's Up has been focused on the great conjunction this year. The first article in the series was presented in the August 2020 What's Up? issue. The second article appeared in the September 2020 What's Up? issue. Please keep reading the What's Up almanac for more information on the great conjunction. Who knows where we will be for the next one?

Astrologers have long pointed at the great conjunctions of Jupiter and Saturn as bringing plague to Earth and so have associated the 2020 conjunction as a cause or portent of coronavirus. Astra's Stargate is an astronomy site and I only want to state that planetary line-ups are all Earth-based. Jupiter will actually lap Saturn on November 2, 2020 if the solar system is viewed from above, but from Earth's surface this event appears to occur 49 days later. Planets in our solar system, including Earth have stable orbits around the Sun. They resonate with each other because they have each made their orbits together for countless millennium. They are entirely predictable when the cycles they follow are understood--they don't rule human lives.

--See You Under the Stars!
Astra for Astra's Almanac