In this guide we'll reveal 10 of our favourite under-appreciated, underrated features to observe on the Moon.
Every amateur astronomer starts off loving the Moon.
They set up their telescopes in their garden, squint into the eyepiece and check what they can see against charts, looking for the best features on the Moon they’ve heard and read so much about.
They whisper in the darkness as they make one discovery after another.
“Ah… so that’s Copernicus!” “That must be Tycho!” “Wow, they must be the Apennine Mountains.”
“Is that… yes, I think it is… the Sea of Tranquility!”
Read our guide on how to observe the Moon and when the next full Moon is visible.
But after a while, the love affair between many new amateur astronomers and the Moon cools. The Moon has begun to look, and feel, a bit ‘samey’.
Frustrated with the inhibiting lunar glare, the astronomer begins to actually resent the Moon they had previously loved so much.
They turn their back on it and avoid it as much as possible, only going out to observe the night sky when they know the Moon isn’t going to be there.
But fear not. We’re going to help those of you who have fallen out of love with the Moon to fall in love with it all over again by showing you 10 off-the-beaten-track lunar features you’ve perhaps never seen before, and nudging you back to a couple of better-known ones that deserve another look.
Here is our guide to some of the most underappreciated features on the Moon, and how to find them.
And if you fancy capturing what you see, read our guides on how to photograph the Moon and how to photograph the Moon with a smartphone.
10 under-appreciated, underrated lunar features
1. Langrenus
When the Moon is young, either a crescent Moon a few days old or on the way towards first quarter, look towards its right-hand side through binoculars and you’ll see a bright spot on the eastern edge of Mare Fecunditatis.
This is the crater Langrenus. Named after a Belgian cartographer, it is 133km wide and 4.5km deep.
Through a telescope at medium to high magnification, it’s a fascinating object, an oval-shaped crater with a mountain peak rising up from its centre and half a dozen terraces in its interior walls.
But its oval shape is an illusion.
Because it’s close to the Moon’s limb we see it at an angle, so like many lunar features it appears foreshortened.
If you flew over the crater, as the Apollo crews did, you would see it is circular.
2. Messier and Messier A
Slowly swing your telescope away from Langrenus, heading towards the northwestern shore of Mare Fecunditatis and just beneath the crater Tarantius you’ll come across a pair of small craters, side by side.
These are Messier and Messier A, named after the famous deep-sky object cataloguer Charles Messier (who gave his name to the Messier Catalogue).
The larger of the two, Messier, is an unremarkable little pit 14km wide, but Messier A is one of the most intriguing craters on the Moon, because a pair of bright rays streak away from its western side like a miniature comet tail or pennant.
hese rays are best seen when the Moon is full or close to full, and illuminated from overhead by the Sun.
Just like the longer, more dramatic-looking rays that surround much larger, ‘celebrity’ craters like Copernicus and Plato, they are made of dusty and rocky debris that sprayed across the Moon when the crater was formed.
3. Montes Spitzbergen
There are some seriously impressive mountain ranges on the Moon, with peaks so jagged and high that they are easily visible through telescopes or even binoculars in some cases, and no doubt brave/crazy climbers will set their sights on conquering them in the distant future.
But scattered across the lunar surface are more isolated peaks too.
If you look towards the eastern shore of Mare Imbrium, just above the large crater Archimedes, you’ll see the Spitzbergen Mountains, a lonely, 79km-wide mountain range that looks like an arrowhead pointing west.
These peaks are all that remain of an ancient crater that was covered over with lava billions of years ago, when Imbrium was formed.
They are best seen under high magnification when the Moon is just past first quarter, because that’s when they are closest to the terminator – the line between day and night on the lunar surface – and cast stark shadows across the lava plain from which they rear up.
4. Mons Pico
Staying with mountains, any future lunar mountain climbers are bound to make a beeline for the northern shore of Mare Imbrium where, just south of the magnificent dark-floored crater Plato, a solitary mountain peak rises from the great lava plain like the worn-down stub of a huge, fossilised tooth.
Named after the Spanish for ‘peak’, this is Mons Pico, 24km across, with a summit that reaches 2.4km up into the black lunar sky.
When the terminator has just swept over this mountain, it’s a very striking sight through a telescope with medium or high magnification.
The slanting rays of the Sun cast a long, dark shadow behind it, which gives the impression of an Everest-like feature.
In fact, while it might once have been that, like most lunar mountains, Pico has been worn down by millennia of micrometeorite strikes and is now more like a high hill with a rounded summit than a jagged mountain.
5. Eratosthenes
Our next target may be one of the Moon’s most striking craters, but like many astronomical objects it’s often overlooked, overshadowed by bigger and more spectacular-looking neighbours.
With the gaping, ray-splashed pit of Copernicus to its west and the curve of the stegosaur spine Apennine Mountains stretching away to the north and east, 60km-wide Eratosthenes is easily visible in binoculars and a stunning sight through a telescope.
At high magnification, you can imagine you’re looking down at it from an orbiting Artemis capsule.
In moments of steady seeing, you can pick out a multitude of features within: its wigwam-shaped central peak, smaller craters spattered across a rugged rumpled floor and its terraced walls, marked with multiple slumps and landslides.
The best time to see Eratosthenes is when it’s near the terminator, when it stares out from the Moon like an empty eye socket.
At full Moon it becomes rather lost beneath Copernicus’s rays.
6. The Straight Wall
You may think the most fascinating features on the Moon are impossible to miss, but some take a lot of tracking down.
Rupes Recta, better known to generations of lunar observers as ‘The Straight Wall’, is only visible clearly when the terminator is sweeping towards it or has just rolled over it.
Then you’ll see what looks like a short, straight line just to the east of the crater Birt.
When the Sun is to its west, the Straight Wall is a bright scratch on the dark surface; when the Sun is low in its eastern sky, the Wall looks like a dark line drawn in charcoal on the Moon’s grey face.
It was once believed this 120km-long and 0.3km-high feature was a towering cliff face, but today we know it’s a fault in the Moon’s crust, a slope with a gradient of just 10 degrees: too steep for future settlers to tow a caravan up safely, but easy for them to hike up, even in spacesuits.
7. Schiller
A sweep across the face of the Moon with a telescope shows that the vast majority of impact craters are round in shape.
But here and there you will come across something that looks different – or just plain weird. Schiller definitely fits that description.
You’ll find it down near the bottom of the lunar disc, not far from the famous crater Tycho and very close to the southern limb.
At 179km long, Schiller is an elongated scar left behind when several objects hit the Moon at a low angle at the same time, ploughing out a long gash in the surface.
A telescope shows it is fatter at one end than the other, like a bowling pin, and a crest or ridge runs down the centre of the thinner section.
The best time to see Schiller is when the apparent wobble of the Moon – known as lunar libration – swings it towards us, and when the terminator is a couple of days away from it.
8. Sinus Iridum
High on the north-western shore of the great Mare Imbrium lies a semi-circular bay that looks like someone – or something – has taken a bite out of the band of high, rugged terrain that separates Imbrium from the dark slash of Mare Frigoris.
This is Sinus Iridum, the Bay of Rainbows, the remains of a crater that formed after Mare Imbrium but was then flooded by its lava, leaving only its jagged northern rim sticking up out of the cooling basalt. Iridum is a favourite with many lunar observers.
Although it can be seen with just a pair of binoculars, through a telescope it is a jaw-dropping sight.
When close to the terminator, its peaks shine like they have been coated with silver or mercury, casting ink-black shadows that stretch for miles, and the floor of the bay, which looks as flat as a sheet of grey paper at other times, is revealed to be covered with countless wrinkles and folds.
9. Eddington
Close to the western limb of the Moon, over to the left of the bright crater Aristarchus, lies Eddington crater – or rather, what’s left of it.
Once this 134km-wide crater was a complete feature, its rim a ring of jagged rock scratching the starry lunar sky.
But when a tsunami of lava swilled into it from the south, the crater was overwhelmed and its rim was partly covered.
All we see today is a semi-circular bay on the most distant shore of Oceanus Procellarum, like a budget version of nearby Sinus Iridum.
This crater remnant is interesting to look at through a telescope because of some subtle, challenging features on its floor, including a very small ‘ghost’ crater and a shallow rille.
It was named after British astronomer, writer and broadcaster Sir Arthur Eddington.
10. Mare Orientale
We are lucky to have the Moon in our sky.
However, we are cheated out of a quite stunning sight, because its most impressive feature is hidden from our direct view, just around the western limb.
Mare Orientale is a dark mare surrounded by three concentric rings of mountains, which are more than 900km across and give it a bullseye appearance seen from above.
Unfortunately we can only get a good glimpse at Mare Orientale temporarily as a result of libration, the Moon’s apparent wobble over time as seen from Earth.
All we can ever see of Mare Orientale, even when libration briefly swings it into better view, is a dark, elongated smudge right on the limb, with hints of brighter ridges around it.
If Orientale had been formed on our side of the Moon, it would dominate its face, and during a total lunar eclipse would transform the Moon into a blood-red eye, staring down at us from above.
Have you completed our lunar tour? What are your favourite underrated features on the Moon? Let us know by emailing contactus@skyatnightmagazine.com.
