A guide to the Moon’s Montes Apenninus

Facts about the moon's Montes Apenninus and how to see it.

Montes Apenninus by Andrew Houghton, Nottinghamshire, UK. Equipment: SkyWatcher Evostar 120mm refractor, Canon EOS 60D camera.

The Lunar Apennines (Montes Apenninus) may not be the very highest mountains on the Moon, but they are certainly the most spectacular.

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The range was named by Johannes Hevelius after our own Apennines – one of the few of Hevelius’s names to have survived the later revision by Giovanni Riccioli.

Montes Apenninus forms the southeastern border of the Mare Imbrium, the largest and most prominent of the regular lunar maria, and is dominant for much of each lunation.

Montes Apenninus by Andrew Houghton, Nottinghamshire, UK. Equipment: SkyWatcher Evostar 120mm refractor, Canon EOS 60D camera.
Montes Apenninus by Andrew Houghton, Nottinghamshire, UK. Equipment: SkyWatcher Evostar 120mm refractor, Canon EOS 60D camera.

The Apennines do not form a continuous border all round the Mare Imbrium, but probably once did, and what we call the ‘Imbrium Basin’ is everywhere traceable; the colossal impact that produced it had profound effects all over the Moon.

From close to Eratosthenes, one of the most splendid and best-preserved of all craters, it runs along the Mare Imbrium’s edge separating it from the smaller, darker-floored Mare Vaporum.

The scene is particularly striking around first quarter, when the peaks cast their long, sharp shadows across the plain. The highest peak in the Apennines, Mons Huygens, rises to about 6.1km.

The Montes Apenninus and Caucasus Regions of the Eight Day Old Moon by David White, Anston, Sheffield, UK. Equipment: Meade LX200 7
The Montes Apenninus and Caucasus Regions of the Eight Day Old Moon by David White, Anston, Sheffield, UK. Equipment: Meade LX200 7″, Celestron NexImage Solar System Imager, Celestron 0.5 focal reducer.

Facts about Montes Apenninus

  • Size 600km long
  • Age Between 3.2 and 3.85 billion years
  • Location Latitude 18.9°N, longitude 3.7°W
  • Recommended equipment for observing 4- to 6-inch telescope

To the north, the Mare Imbrium is bounded by the Montes Alpes, which do not join up with the Apennines. There is a gap between the two ranges, so that Imbrium’s floor is connected with that of the adjacent Mare Serenitatis – there is a difference in level and also in age.

The lunar Alps are by no means the equal of the Apennines, but they have special interest because they contain features not found elsewhere on the Moon. Of particular note is the huge Vallis Alpes, a colossal gash through the mountains.

Last, but by no means least, is the Sinus Iridum, or Bay of Rainbows. It must once have been a major crater at the edge of the mare but the seaward wall has been flooded and is now barely traceable, so we are left with a large bay.

You can watch it as the Sun rises over it. Obviously, the Sun’s rays first catch the peaks on the far side, while the bay itself is left in darkness.

This is generally known as the ‘Jewelled Handle’ and, of course, occurs once in every lunation. It is a phenomenon known as a clair-obscur effect. For advice on how to see it, read our pick of the best clair-obscur effects to see on the Moon.

Clair obscur effect jewelled handle
The clair obscure effect on the Moon known as the Jewelled Handle. Credit: Pete Lawrence

The mare does not contain many large craters, apart from the main three, of which the largest is the 80km Archimedes.

There can be no better known feature  on the whole of the Moon than the Mare Imbrium. One can picture the scene when the huge meteoroid crashed down so long ago!

Below is a selection of images of Montes Apenninus captured by lunar astrophotographers and BBC Sky at Night Magazine readers.

For more advice on making the most of the Moon, read our guide on how to observe the Moon or our pick of the best features to observe on the Moon.

Or you could try your hand at lunar photography with our tutorial on how to photograph the Moon. If sketching is more your thing, read our guide on how to draw the Moon.

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And don’t forget to send us your images or share them with us via Facebook, Twitter and Instagram.

Apennine Mountains by Alastair Woodward, Derby, UK. Equipment: Sky-watcher 6
Apennine Mountains by Alastair Woodward, Derby, UK. Equipment: Sky-watcher 6″ Newtonian, EQ3-2, QHY5L-II
Lunar Apennines by Ian Peck, Londonderry, N. Ireland. Equipment: SkyWatcher200p, Logitech C270HD webcam.
Lunar Apennines by Ian Peck, Londonderry, N. Ireland. Equipment: SkyWatcher200p, Logitech C270HD webcam.
Montes Apenninus by Neil Bintcliffe, Huddersfield, UK. Equipment: Celestron C8, Celestron GT Advanced mount, Trust WB 5400.
Montes Apenninus by Neil Bintcliffe, Huddersfield, UK. Equipment: Celestron C8, Celestron GT Advanced mount, Trust WB 5400.
Lunicus and Eratosthenes and Lower Appennine Highlands by Brian S Parker, Wales, UK. Equipment: QHY5T 200mm Newtonian, Neq6 pro.
Lunicus and Eratosthenes and Lower Appennine Highlands by Brian S Parker, Wales, UK. Equipment: QHY5T 200mm Newtonian, Neq6 pro.
Eratosthenes and Montes Apenninus by Keith Mayes, UK. Equipment: 8
Eratosthenes and Montes Apenninus by Keith Mayes, UK. Equipment: 8″ Celestron, Orion IV planetary imager.
Apennine Mountain Range on the Moon by Alex Houston, Tullibody, Clackmannashire, UK. Equipment: Sky-watcher Evostar-100ED2 PRO, DMK 41AM02.AS mono CCD, 3x Barlow lens.
Apennine Mountain Range on the Moon by Alex Houston, Tullibody, Clackmannashire, UK. Equipment: Sky-watcher Evostar-100ED2 PRO, DMK 41AM02.AS mono CCD, 3x Barlow lens.
Apeninnes on the Terminator by Peter J Williamson FRAS, Whittington, Shropshire, UK. Equipment: Celestron 9.25
Apeninnes on the Terminator by Peter J Williamson FRAS, Whittington, Shropshire, UK. Equipment: Celestron 9.25″ SCT, ZWO120ASIMM CCD
The Apennine Mountains by John Short, Whitburn, Tyne and Wear, UK. Equipment: Celestron 8SE, Hyperion 8-24mm, Canon 70D
The Apennine Mountains by John Short, Whitburn, Tyne and Wear, UK. Equipment: Celestron 8SE, Hyperion 8-24mm, Canon 70D
Apennine Mountain Range by James Hardy, Ferndown, Dorset, UK. Equipment: Skywatcher Black Diamond Ed100, Heq5pro Mount, Zwo 120mc
Apennine Mountain Range by James Hardy, Ferndown, Dorset, UK. Equipment: Skywatcher Black Diamond Ed100, Heq5pro Mount, Zwo 120mc
Montes Apenninus Mountain Range by Daniel Orchard, Wiltshire, UK. Equipment: Explorer 200p, otor driven ra EQ5, ASI120mm with red filter, 3x barlow.
Montes Apenninus Mountain Range by Daniel Orchard, Wiltshire, UK. Equipment: Explorer 200p, otor driven ra EQ5, ASI120mm with red filter, 3x barlow.
INA, a volcanic complex at the foot of the Apenninus! by Avani Soares, Parsec Observatory, Canoas, Brazil. Equipment: C14 Edge, ASI 224, Powermate 2X, L filter
INA, a volcanic complex at the foot of the Apenninus! by Avani Soares, Parsec Observatory, Canoas, Brazil. Equipment: C14 Edge, ASI 224, Powermate 2X, L filter
The Lovers of Night - The Heart of the Moon by Fernando Oliveira De Menezes, New York. Equipment: C11 Edge, Powermate 2x, So 290mc.
The Lovers of Night – The Heart of the Moon by Fernando Oliveira De Menezes, New York. Equipment: C11 Edge, Powermate 2x, So 290mc.
The Moon by Alex Bell, Bath, UK. Equipment: Canon 600D, Atik CLS filter, 8
The Moon by Alex Bell, Bath, UK. Equipment: Canon 600D, Atik CLS filter, 8″ Ritchey Chrétien, iOptron iEQ30 mount.
Moon by David Millar, Abernethy, Perthshire, UK. Equipment: 12
Moon by David Millar, Abernethy, Perthshire, UK. Equipment: 12″ Skywatcher Dobsonian, Google Pixel2.
Apennines by John Press, Burnham on Crouch, UK. Equipment: 8
Apennines by John Press, Burnham on Crouch, UK. Equipment: 8″ Celestron Evolution, ZWO ASI 224mc.