Sketch what you see
It’s simple and a great way to fine-tune your Martian geography know-how
Start sketching the Red Planet long before opposition and it won’t be long before you have drawings of the entire surface. Follow these five simple steps:
1. First, you’ll need to make a blank to draw on. Download yours in this month’s Bonus Content (see page 5) or make your own by drawing a white circle 50mm in diameter.
2. Spend a good 15 minutes observing Mars at your telescope before starting. What details are visible? Can you see a polar cap? Are there any prominent dark markings? What else can you see? Experiment with magnification so that the features are not too blurred.
3. You’re ready to draw. Start by putting in the terminator. Near opposition, Mars is 100 per cent illuminated, but either side of opposition, the planet has a phase. The terminator is not necessarily at right angles to the central meridian, so draw it carefully.
4. Now add the most prominent dark features, then the polar cap if you can see it. Add subtle features like clouds or delicate streaks. The Martian limb may be quite bright if clouds are present. Complete your drawing within 12 minutes: any longer and Mars’s rotation will have significantly moved the features.
5. Finally, record the date, time (in UT) and telescope size and details. You can add other data like the value of the central meridian: this tells you which feature is on the north–south line at the time of your drawing.
Now try this
Once you’re comfortable sketching the Martian surface, you can go on to experiment with using different colour filters. Blue enhances white clouds, orange/red brings out any orange clouds. If your drawing was made using a filter, record that too. The more you draw Mars, the more you will see!
Hellas and Argyre. There may be bright clouds over Edom and the volcanoes, while the northern polar cap should now be easier to see.
Opposition… and occultation too!
On 8 December opposition occurs and, remarkably, we can look forward to a rare lunar occultation of Mars on the same date. See it with the naked eye, binoculars or a telescope. At about 04:00 UT, look towards the west and the Moon will be close to Mars in the constellation of Taurus. Mars is predicted to be ‘touching’ the western limb of the Moon at about 04:57 UT, when viewed from the centre of the UK. The exact timing will depend on your location (from London it occurs around 05:00 UT; from Edinburgh at 04:52 UT), so it pays to start observing slightly earlier. The Moon will then pass over Mars, with the planet predicted to reappear around 05:57 UT (from the centre of the UK). Through a telescope you’ll be able to watch the disc pass down behind the lunar limb, almost as if Mars is setting on the Moon!
Later on 8 December, turn your telescope to Mars at 19:00 UT and you will see the Solis Lacus (the eye of Mars) looking straight back at you. The north polar cap should be visible at the bottom of the disc (in a mirror-inverting telescope) and Olympus Mons will be located near the bottom right limb. If there are any bright clouds present, this huge volcano will appear quite bright even in medium-sized telescopes.
Hunting flashes
There is a fascinating phenomenon known as
‘Mars flashes’, brilliant ‘starlike’ flashes that can last for a number of seconds. They occur in two regions: Edom and Tithonius Lacus (see map, page 62), and although occasional flashes have been reported elsewhere, these are the main two sites to keep an eye on. The flashes are thought to be caused by reflections from ice crystals in clouds over these regions. The geometry has to be just right. If you were standing at these sites, Earth and the Sun would have to be overhead near the zenith.
This special alignment between the Sun, Earth and Mars is very rare, and doesn’t necessarily occur at each opposition. Check our table of predicted dates and times on page 63 and see if you can detect these light signals from Mars.
Dr Paul Abel is an astrophysicist and the Director of the British Astronomical Association’s Mercury and Venus section
A lunar occultation of Mars, taken from Brazil on 6 September 2020. Weather permitting, the occultation on 8 December should look just as spectacular
The spring equinox in the north of Mars (Ls = 0°) starts on Christmas Day; the onset of the warmer weather (for Mars) will see the sublimation of the north polar cap – ice changing directly from a solid state into vapour, returning volatiles to the Martian atmosphere. Brilliant fogs and hazes will collect along the boundary of the northern pole, making the whole area very brilliant. Keep an eye on Hellas, Argyre and Eridania, as bright, white clouds are likely to collect around here. Mars will still be a viable target months after opposition. Owners of small- to medium-sized telescopes can follow it until the end of February 2023, with the planet remaining above 10 arcseconds. Larger telescopes will continue to show details on Mars well into April.
During January and February, Mars’s tilt as seen from Earth means we will get a good look at the equatorial regions. See if you can observe the north and south polar caps at the same time. During these months it is autumn in the south and the great southern cap will be starting to form, continuing to grow until winter.
There will be lots to see on Mars over the coming months, making it a spectacular sight before and after opposition. Whether it’s a large global dust storm or Martian light signals, you can chart your own telescopic adventures on the Red Planet.