2020: A Mars Odyssey

[Nightspore]

 

 

 

I was really excited about the Mars opposition at the start of 2020. The last one (2018) was a disappointment because of the all-encompassing planetary dust storm. I’d eagerly anticipated that opposition too and had purchased Celestron and Orion Mars filters especially for it. So naturally, in 2020, I got early Mars fever and needed to socially un-distance myself from my telescopes to ameliorate the condition.

 

 

The first glimpse of Mars through a telescope was at about 05:00 on May the 11th. It was at around 16° altitude and rising steeply in the east. Mars then being apparently around 214,000,000 km from Sol and roughly eight arc seconds in diameter. I was using my Sky-Watcher Evostar 72ED DS Pro. It’s not a large telescope and I didn’t expect to see much detail in the early daylight. I could see the phase though and at 168x I could even make out surface features. The bright southern polar cap was very apparent and I was pretty confident that the dark albedo feature of Syrtis Major could just be perceived. Later I checked my software and the Syrtis Major Planum was indeed visible at that time. I distinctly remember thinking that it bodes well for future Mars observations this year. I always enjoy seeing Syrtis Major as it was the first documented land mass discovered on another planet. It was recorded by Christiaan Huygens in a map of Mars he drew in 1659. Huygens is also famous for the Huygens eyepiece and the pendulum clock inter alia.

 

 

I had four more sessions in May, three of them with my modified Evostar 80ED DS Pro. Through June, July and August I had ten sessions on Mars, including an early morning session after witnessing the C/2020 F3 (NEOWISE) comet with the 72ED. I started to notice a white albedo phenomenon in the Martian northern hemisphere. I suspected high altitude clouds at first, then wondered if it was an optical effect caused by the various light train combinations utilised with my refractors. I ruled the latter out after an early morning session with my 102mm Maksutov. I’d initially gone out to view the Venus' greatest western elongation. However, intermittent clouds temporarily obscuring Venus gave me the opportunity to view Mars a while as well.

 

 

In September I managed nine more Mars sessions. On the 9th and 14th I had 238x with my 102mm Altair Starwave ED-R doublet and saw some incredible detail including the Terra Sirenum, Solis Planum areas and the ‘Eye of Mars’ feature. I was very impressed with the images produced by the Starwave at 238x. In hindsight I’ve wondered if I could have pushed to 60x per inch of aperture. I was also particularly impressed with the Eos Chasma, Xanthe Terra and Nectaris Fossae areas. Later in the same month two further sessions with the 80ED and a single session with the 127mm Maksutov were quite outstanding. The image with the 127mm Sky-Watcher Maksutov on the 26th was dazzlingly bright. At 257x the Syrtis Major Planum, the Hellas Planitia impact basin, and the Arabia Terra region were very distinct. The triangular Syrtis Major albedo feature was memorably outstanding.

 

 

I realised that the ‘white albedo feature’ I’d observed regularly in the north were almost certainly the northern polar hood (NPH) clouds that form over the northern hemisphere in the Martian winter. In late September, and as the opposition approached, Mars became very bright. Filters have always been useful on Mars. I regularly used a Baader 570nm orange longpass filter, Baader Contrast Booster and a magenta coloured Tele Vue Bandmate Planetary filter among others. As the planet became brighter still I found that I needed to stack a single polarising filter with my preferred filters to stem the overbearing glare.

 

 

In late September and early October the southern polar cap seemed to become less distinct and difficult to observe. However it became more visible later in October. Although it had been slowly and obviously shrinking in the Martian summer it had also concomitantly lost a lot of its brightness. I assume a polar dust storm obscured it for a few weeks. In fact, I once had to resort to using a Baader light blue 470nm bandpass filter just to be able to locate it. Eventually, although smaller, it returned more or less to its former brilliance. The NPH clouds also appeared to become less distinct towards November. I was well prepared for an October the 5th session with the 127mm Mak’ and my William Optics binoviewers.

 

 

Unfortunately it was one of those sessions that didn’t at first go quite as planned. After fumbling about in the dark a bit I ended up putting the 1.6x Barlow into the nosepiece instead of the 2x one. I then wondered why Mars was looking a little small at 123x. Eventually I realised I had used the 1.6x Barlow and went with a pair of 12mm GSO Plossls for about 205x and 10mm SvBony 10mm ‘plastic fantastics’ for around 246x. Although I had originally envisaged quite a few bino sessions this was the only outing in stereo.

 

 

On October the 5th I finally set-up and polar aligned my Sky-Watcher EQ5 mount. This is then usually kept outside and covered with a tarpaulin when not in use. Effectively making my TS Optics (GSO) 150mm, f/6 Newtonian a kind of ‘grab and go’ telescope. I had around fifteen Mars sessions in October and most of them were with the 150mm Newtonian. The perigee (around 211,000,000 km from Sol) on the 6th was intense and I had a good 300x with a 6mm Astro Hutech orthoscopic combined with a 2x Vixen Deluxe Barlow. Two nights later I even had a relatively sharp 360x (60x per inch of aperture) using a 5mm orthoscopic and the same Barlow. On the opposition itself I had set-up the 150mm Newtonian in anticipation a good hour earlier than transit. Unfortunately clouds frustrated my viewing until at least an hour after transit. I waited them out and was rewarded with a very nice view of the ‘Eye of Mars’ nicely framed between the dark albedo features of the Terra Cimmeria and Terra Sirenum.

 

 

I managed eleven nights in November, the last being on Monday the 30th, all with the 150mm Newtonian. Mars was now visibly smaller with the phase returning and the overpowering glare had diminished somewhat. By the 3rd it had dropped below 20 arc seconds. Interestingly, in early November sessions, I discovered that a single polarising filter on its own often produced the most defined surface image detail. On the evening of Wednesday the 18th I observed from about 20:00 (when the OTA had reached thermal equilibrium) until transit around 21:00. Apart from occasional windy gusts rocking the tube the seeing didn’t allow me to observe any sharp detail and the southern polar cap was very difficult to perceive. It’s a very good possibility that the heat of the southern summer had produced another dust storm.

 

 

On the 19th the polar cap was much brighter, although the definition of surface features was not good. The entire planet seemed brighter than the previous night. Whether this was due to better transparency or not is difficult to say. The polar cap was very bright even when using a Baader 610nm red longpass filter. It may be that the dust clouds have a high intrinsic reflectivity and were making Mars appear brighter. I managed a slightly earlier session on the evening of Sunday the 22nd (forty days after opposition) with the 150mm Newtonian. At 281x and a red filter the polar cap was small but relatively bright. It wasn’t so apparent with yellow or orange filters. Although I could see the dark shapes of the Terra Sirenum and the Noachis Terra the dark albedo features weren’t quite as defined as I’d expected. I believe the best image I saw in the session was with an orange filter, redolent of the 2018 opposition, when the dust storm had abated slightly revealing hitherto obscured surface features. On the 30th I managed 360x as the seeing was very good (Antoniadi II~I). This time I used an entire gamut of filters including red, blue, yellow, orange and magenta. I used an inexpensive (30 quid) ‘Mavis Laven’ 2.5mm TMB clone and was quite amazed at how good the image was. The phase was very distinct and the limb was extremely sharp. Limb clouds were observed along with the diminished polar cap. Dark albedo features like the Noachis Terra region could be identified, although the dust storm was still pretty much extant.

 

 

I had a further six sessions in December all with either the 80ED, the 72ED or the modified ST102. I actually had half of those with the ST102. With all of the ST102 sessions I used the 2.5mm ‘Mavis’ combined with a Celestron Mars filter (200x).

 

 

Interestingly there was only a minimal ‘purple hazing’ around Mars through the achromat. Presumably the magenta coloured Celestron filter had taken out a lot of the blue end of the spectrum. The dust storm had appeared to have abated somewhat. Even though Mars was rapidly shrinking, surface features, high altitude clouds, and the southern polar cap could still be seen. All in all 2020 was a great year for observing Mars in my experience.

 

Edited February 9, 2021 by Nightspore