Moon tour
Finding this lunar crater won’t leave you howling with frustration on cold January nights
Finding this lunar crater won’t leave you howling with frustration on cold nights
Many people don't realise that the full Moons seen throughout the 12 calendar months have names, often rooted in nature. These can be traced back to before the Julian calendar was followed and have ties to the Native Americans. For example, May’s full Moon is the ‘Flower Moon’. In November the ‘Hunter’s Moon’ shines over our Bonfire Night celebrations and as December ends late-night Christmas shoppers scurry around looking for last-minute gifts beneath the ‘Cold Moon’.
This January, the full Moon that will illuminate our frosty grass and windscreens and the snowmen slumping in our gardens is known as the ‘Wolf Moon’, named by Native Americans after the mournful howling of hungry wolves searching for food halfway through winter. Obviously wolves are in quite short supply in the UK these days, but there is one place you can guarantee seeing one this month – on the Moon itself. Our Moon Tour destination for January is the small crater ‘Wolf’.
Named after the accomplished German astronomer Max Wolf – who discovered several comets and supernovae, proved dark nebulae were clouds of interstellar dust and discovered no fewer than 248 asteroids in his lifetime – Wolf crater is 26 kilometres (16 miles) wide and not quite a kilometre deep, making it one of the smaller craters we’ve visited on our long tour. It lies almost in the centre of Mare Nubium, the ‘sea of clouds’, a roughly circular dark stain on the Moon which can be found to the southeast of the much larger Oceanus Procellarum. The crater was photographed by the crew of Apollo 16 in 1972, which landed in the Descartes Highlands region, and was imaged again more recently, but in much higher resolution, by the Lunar Reconnaissance Orbiter’s cameras.
Although it is small itself, Wolf can be found quite easily because it lies halfway between two larger, more obvious craters: Bullialdus to its upper left and Pitatus to its lower right. Far too small to be seen with the naked eye and a challenge with a pair of binoculars, Wolf sadly looks nothing like a wolf. Through a telescope’s low-power eyepiece it appears as a roughly heart-shaped feature. Higher magnifications reveal a gap in Wolf’s southern rim which makes it look more like a small vase or the Greek ‘Omega’ symbol than a heart.
Wolf’s walls are relatively featureless, thicker and wider in some places than others, and its floor is dark and flat with a short, curved chain of four small secondary craters on its western side. The most remarkable thing about Wolf is probably the bright apron of ejecta that spreads out from its sides and bottom, like an open cloak. Look at that through your telescope’s highest magnification eyepiece and you’ll see it is very rugged and hummocky, spattered with its own small craters. It looks like a small part of the lunar highlands surrounding the crater.
So when can you see this crater for yourself? At the start of our observing period Wolf is not visible, totally hidden in shadow. However, by the evening of 4 January the terminator will have swept over the crater like a dark tsunami and Wolf will be illuminated from the east. This will be a good time to look for details and small features on its floor and that surrounding ejecta apron, as they are lit by the slanting rays of the low Sun. Wolf will remain fully illuminated between 4 and 18 January, but by the 19th the terminator will have rolled over it again and it will have vanished, not to reappear until next month.
While Wolf might not be the most striking or dramatic crater on the Moon, it is definitely worth a look at through your telescope. It's a valuable reminder that the Moon has a lot more to offer the observer than the ‘celebrity’ features like Copernicus, Tycho and the Sea of Tranquillity.