What’s got eight orbiting spacecraft, three robotic rovers on its red surface and will dramatically disappear behind the Moon briefly during December 2022? This rare ‘occultation’ doesn’t just happen at any random time, but when the planet Mars is almost to the day at its biggest, brightest and best-looking for almost two years. Should you try to photograph this unusual ‘eclipse of Mars’? Here are some of our top tips to get you started…

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1 What is an occultation? 

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An ‘occultation’ is the technical term for when one object is hidden by another object that passes between it and the observer. That’s exactly what will happen on December 7/8, 2022 when the Moon – around 384,400 kilometres from Earth – will ‘eclipse’ Mars while the ‘red planet’ is at a distant 81 million kilometres million miles in the background. It’s a rare occurrence not only because the Moon moves across to cover Mars, but that it happens while both Mars and the Moon are at their brightest. December 7 is also the date of Mars in ‘opposition’ and of December’s full Moon! That means that a particularly bright Mars will disappear and reappear against the bright limb of the Moon. Let’s hope for clear skies… 

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Author tip:

As the Moon orbits our planet every 27 days it regularly occults other objects in the sky – including planets – but only from relatively narrow paths across Earth’s surface. That's because the Moon’s exact apparent position in the night sky can differ by as much as four Moon diameters when viewed from different locations on Earth. 

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2 What will happen, when and where 

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The Moon occulting Mars will last about an hour and will be visible in its entirety from Western Europe, Greenland and most of the U.S. and Canada. The event will happen in the early morning of December 8, 2022 for those in Western Europe and in the early evening of December 7, 2022 for those in North America. Wherever you are, the eastern limb of the full Moon will start to eclipse Mars. After about an hour behind the Moon, Mars will reappear on the western limb of the Moon.

What’s really special about this event is that the entire event will be preceded by the rise of a full Moon. The full Moon in December is always known as the ‘Cold Moon' in the northern hemisphere because of the time of year it occurs, but also as the ‘Long Nights Moon’ and the ‘Moon Before Yule’.

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Author tip:

‍Although its occulting of Mars is the highlight you should also be in place at the time of moonrise where you are on December 7, 2022 to capture its orangey disk as it rises above the eastern horizon during dusk. As it rises you’ll see Mars to its lower-left, first appearing just after the Moon.  

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3 Getting your timing and angles right

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The two key moments of this occultation are the 30 seconds either side of Mars disappearing behind the Moon. During those short windows you’ll be able to see – and photograph – the bright red planet alongside, and also partially covered by, the bright limb of the Moon. Exactly when it happens depends on where you are within the path. For example, from London, Mars will disappear behind the Moon at 04:58 on December 8, 2022 while 27º above the western horizon. It will reappear at 05:59 while 18º above the western horizon. From Los Angeles, Mars will disappear behind the Moon at 18:31 PST on December 7, 2022 while 23º above the eastern horizon. It will reappear at 19:31 PST while 35º above the eastern horizon. 

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Author tip:

The exact timings for various locations for this event – as well as a useful map – are provided by the International Occultation Timing Association, though for location-specific timings enter your location into In-The-Sky. Consult planetarium software like Stellarium to see exactly what’s going to happen, when and where in the sky where you are.

4 Settings and planning the shot

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Photographing the occultation will be a challenge because Mars and the Moon will be so close to each other. The easiest way to capture the event will be with a wide-angle lens at a wide aperture (f1.8-f4) on a tripod, taking short exposures of less than two seconds and experimenting with ISO depending on the brightness of the sky. The Moon and Mars will look very small in the shot, but they will be visible. You may have to take two separate exposures for Mars and the Moon, the latter of which will be very bright indeed and may overwhelm the planet in one exposure.

If you’re going to use a telephoto lens (300mm at least, 1000mm if possible) then the technique will be the same for photographing any full Moon. However, for a frame-filling shot the only choice is to use a telescope. There are two ways to do this; by attaching a DSLR or mirrorless camera using a T-adapter or by holding a smartphone up to the eyepiece (afocal photography).

Whatever you use, getting a shot of Mars just before or after the occultation will be all about timing! 

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Author tip:

‍Although you can watch the occultation with the naked eye, or with binoculars the very best view will be through any small telescope. The main limiting factor on actually seeing this event is, of course, the weather. The northern latitudes of the northern hemisphere are not exactly known for clear weather in December, so do check forecasts closer to the time. 

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5 Mars at opposition

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It’s something of a celestial coincidence that the occultation is occurring at almost exactly the same moment considered to be the best time to view and photograph Mars for over two years – and until 2025. That moment is Mars’ ‘opposition’. A planetary opposition is when Earth gets between it and the Sun. The result is that from Earth that planet looks its biggest and brightest of the year. It’s also the only time the planet is fully illuminated by the Sun as seen from Earth. Since it takes 687 days to orbit the Sun, Mars only reaches opposition once every 26 months. That next happens on January 16, 2025.

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‍Author tip:

Only at opposition does a planet rise in the east at sunset and set in the west at sunrise. Mars will therefore be in the night sky for the entire night on December 7/8, 2022, so if you can stand the cold it’s the perfect time to photograph and study the planet through a telescope, if you have one. If you know you’re going to receive, or give, a telescope for Christmas 2022 then consider getting that exchange done a few weeks early.