Mars Opposition 2020
In Harry Potter, a Centaur surveys the sky through the trees of the Forbidden Forest at Hogwarts and opines, ‘Mars is bright tonight’, a portent of Voldemort’s return. In reality, Mars is regularly bright for no more sinister reason than orbital mechanics: every couple of years when it’s near ‘opposition’, when its orbit brings it to the opposite side of Earth from the Sun and so close by.
Right now (yesterday, the 14th October 2020 to be precise) Mars is again in opposition, although exact orbital alignments mean Mars was actually at its closest to Earth a few days earlier. It’s impossible to miss - that brilliant yellowish (not red in R.L.) star rising in the west from mid evening. Unlike other recent oppositions though, Mars gets good and high in the sky for northern latitudes this time, crossing the meridian here at about one in the morning local time at an altitude over forty degrees. And even though this isn’t the closest opposition in this cycle (that was the ‘perihelic’ opposition of 2016) it’s only about 10% smaller and much better placed here in Europe – perfect for viewing or imaging!
Mars’ closest 2020 approach around the 6th October was a total weather washout for me and I thought opposition night was going the same way. I got a quick look at about nine thirty with a 4” Takahashi FC-100DZ refractor from my balcony, just enough to spot some tantalising albedo markings at 200x. But no sooner had I got my dome open than the clouds rolled in, typical!
Then, just as I was already in bed and dozing at midnight, I spotted a brilliant yellow star through a gap in the curtains. I waited to see if it would blink out behind clouds again, but it didn’t. So I reluctantly dragged myself back out of bed, knowing I’d regret it if I was lazy. A clear dark sky, cool but not cold and with just a few scudding clouds, greeted me as I stepped into the garden. The stars were steady, not twinkling, the all-important sign of good seeing. Mars was so bright those stars around looked dim.
I soon had the dome back open and my 7” refractor pointing at Mars over the roof of my house. A pair of 5mm Nagler eyepieces and an old binoviewer giving 280x gave a fabulous view. The atmosphere held still, as those twinkle-free stars had promised. Mars has a similar rotational period to Earth, so the visible part varies slowly from night to night and tonight was a view with special significance for me, beyond the closeness of opposition.
What I could see on the (large for Mars) 22.3” full disc, was this: a broad swathe of dark markings and a tiny bright polar cap in the southern hemisphere. In the northern half, an expanse of seemingly featureless ochre desert shimmered tantalisingly. I have a lifelong fascination with volcanoes and it so happens that the largest one known anywhere was lost somewhere in that desert. Generally, Olympus Mons, the largest of a group of giant volcanoes in the Tharsis region, is only visible when it’s covered in white cloud (‘Nix Olympica’, the ‘snows’ of Olympus). Not much cloud tonight, but that didn’t stop me looking. And looking …
For the next hour or two, I relaxed in the red-lit quiet of my observatory and enjoyed Mars as I only rarely get to see it – a proper little world with real details visible whenever the seeing went especially still. This is the simple, immediate visual astronomy I like best. Eventually I resolved darker lobes and subtle E-W bands in the shaded southern region and a dark streak in the far south east. Meanwhile, some blueish bright areas on the far western limb were probably patches of hazy high cloud. In occasional split-second moments the view stilled further to reveal fleeting structure within the dark areas, a hint maybe of why Lowell and other believed they saw canals. No artist, but I tried to sketch what I’d seen.
Then, in the small hours with Mars descending past the meridian, the seeing steadied even more. My local female Tawny owl screeched from the copse across the field and some cat (I hoped!) howled from the gardens up the road. I waited. Eventually, a spot or two flickered out from that ochre desert in the Martian north west and were gone in an instant. I recorded, ‘Spots! Volcanoes?’ on my sketch. Imagination? Or had I really glimpsed Olympus Mons? Well, perhaps. Then again, Mars will be well placed on the run-up to Christmas of this strange year of 2020; and if I’m lucky I’ll get to search for Mars’ volcanoes again.
Mars rising above my chimney pot!