How to see crater Clavius on the Moon

Read our lunar observing guide and find out how to locate the Clavius crater on the Moon, and what to look for once you find it.

Clavius is a wonderfully rugged moon crater, ripe for observing with a telescope. Credit: Pete Lawrence

Located deep in the southern lunar highlands, few craters on the Moon are as majestically commanding as mighty Clavius. It’s a familiar feature on the Moon because of its size, characteristic appearance and because it’s prominently on view between the first and last quarter phases.

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The start of this phase period is popular because it represents a time when viewing can be done at a relatively civilised time in the evening.

It would also make a good target for photographing. For more on this, read our guide on how to photograph the Moon.

Crater Clavius is massive, with a diameter of 225km. For comparison, this makes its diameter roughly equivalent to the straight line distance between Cardiff and Manchester.

From Earth, Clavius has an elliptical appearance, which is a direct result of its southerly lunar latitude. The elliptical shape is due to an effect called foreshortening. If we were able to hover directly over it, Clavius would look more-or-less circular.

For more on lunar observing, read our complete guide to lunar maria, how to see Earthshine and the science behind a supermoon.

Facts about crater Clavius

  • Size 225km
  • Longitude/latitude 14.7˚ W, 58.6˚ S
  • Age 3.9 billion years
  • Best time to see One day after first quarter and last quarter
  • Minimum equipment 10x binoculars
Where to look for Clavius on the Moon. Credit: Pete Lawrence
Where to look for Clavius on the Moon. Credit: Pete Lawrence

What does Clavius look like?

For such an old feature in such a heavily cratered part of the Moon, Clavius holds its appearance well.

Its rim edges are rugged but well-defined all the way round. One possible relaxation to this may be seen just to the west of 53km Porter, which rudely interrupts Clavius’s rim along the northeastern section.

The rim-line just to the west of Porter, appears to have been smoothed out. This is due to the extremely battered 44km crater Clavius M, almost completely disguised, sitting immediately next to Porter.

Head directly south of Porter to the southeast section of Clavius’s rim and here you’ll find another interruption caused by 55km Rutherfurd.

Eyes of Clavius, by Avani Soares.
A feature known as the Eyes of Clavius, created by sunlight illuminating two crater rims. Credit: Avani Soares.

It’s interesting to compare the appearance of Porter and Rutherfurd. Although they are similar in size, Rutherfurd’s floor is rugged and cracked, while Porter’s is smooth with a neatly placed central mountain complex.

Rutherfurd also has a central mountain, but it’s displaced towards the northeast. An interesting pattern of ejecta ‘furrows’ appears to pass north and northwest of Rutherfurd.

Clavius's diameter is roughly equivalent to a straight line between Cardiff and Manchester

These, the offset mountain, and the fact that Rutherfurd’s actual shape (if foreshortening was removed) is elongated north to south, suggests the crater was formed by a low angle impact from the south or southeast.

Rutherfurd marks the starting point of an impressive arc of ever decreasing craterlets.

A sunset over Clavius, by Harvey Scoot.
A sunset over Clavius. Credit: Harvey Scoot.

Immediately north of Rutherfurd is 28km Clavius D an easy target for a small telescope.

Continue northwest to 21km Clavius C. A small scope shouldn’t have any problems here either.

Continue west to 13km Clavius N, which requires at least 100mm of aperture to see clearly.

To the southwest of N is 12km Clavius J, again a good target for a 100mm scope.

A panorama around the Clavius crater, by Houssem Ksontini.
A panorama around the Clavius crater, by Houssem Ksontini.

If you want to test your telescope’s resolving power, head back to Clavius N and look north to a point just inside Clavius’s rim. Here lies 6km Clavius W, a size which starts to strain the limit of a 100mm scope.

Approximately one-quarter of the way from Clavius N towards W, offset slightly west, is 4km Clavius O which requires a 200mm instrument to see.

There are many more lumps and bumps to see on Clavius’s floor, and it’s an interesting exercise to see how many of those annotated in our main image can be spotted visually.

Have you managed to observe or even photograph Clavius? Let us know! Get in touch by emailing contactus@skyatnightmagazine.com or via Facebook, Twitter or Instagram.

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Images of Crater Clavius

A selection of astrophotos of the famous lunar crater captured by astrophotographers and BBC Sky at Night Magazine readers.

Clavious, Moon by Brian.M.Johnson, Hove, UK. Equipment: Meade LX200, Analog Video
Clavious, Moon by Brian.M.Johnson, Hove, UK. Equipment: Meade LX200, Analog Video
Clavius by Jacques Reusens, Walem, Belgium. Equipment: Skywatcher 8
Clavius by Jacques Reusens, Walem, Belgium. Equipment: Skywatcher 8″ F6 Dob, Eq mount, Philips webcam, Televue barlow 2x, Meade barlow 3x stacked
Clavius and the South of the Moon by Mike Jennings, Leeds, UK. Equipment: Celestron C8 SCT, QHY5 camera.
Clavius and the South of the Moon by Mike Jennings, Leeds, UK. Equipment: Celestron C8 SCT, QHY5 camera.
Clavius by Alan Baldwin, Cleethorpes, UK. Equipment: Celestron 9.25 SCT, HEQ5 Pro, SPC900 modded with 618chip.
Clavius by Alan Baldwin, Cleethorpes, UK. Equipment: Celestron 9.25 SCT, HEQ5 Pro, SPC900 modded with 618chip.
Clavius and Southern Highlands by Brian S Parker, Wales, UK. Equipment: 200mm Skywatcher, QHY5T CCD, NEQ6 mount.
Clavius and Southern Highlands by Brian S Parker, Wales, UK. Equipment: 200mm Skywatcher, QHY5T CCD, NEQ6 mount.
Clavius Region! by Jarrod Bennett, Mutxamel, Spain. Equipment: Skywatcher 150PL, ASI120mm, Baader UV/IR cut filter.
Clavius Region! by Jarrod Bennett, Mutxamel, Spain. Equipment: Skywatcher 150PL, ASI120mm, Baader UV/IR cut filter.
Clavius by Alastair Woodward, Derby, UK. Equipment: Skywatcher 150, EQ3-2, QHY5L-II
Clavius by Alastair Woodward, Derby, UK. Equipment: Skywatcher 150, EQ3-2, QHY5L-II
Clavius Crater by John Brady, Lancashire, UK. Equipment: Skywatcher 200p, DMK41 mono CCD, 3x Barlow
Clavius Crater by John Brady, Lancashire, UK. Equipment: Skywatcher 200p, DMK41 mono CCD, 3x Barlow
Clavius by David de Cuevas, Treize Vents, France. Equipment: Skywatcher 150/750, EQ6, ZWO ASI 224, Barlow x3.
Clavius by David de Cuevas, Treize Vents, France. Equipment: Skywatcher 150/750, EQ6, ZWO ASI 224, Barlow x3.
Clavius Crater by Neil Phillips, Great Notley, Essex, UK. Equipment: 12
Clavius Crater by Neil Phillips, Great Notley, Essex, UK. Equipment: 12″ Skywatcher 300p Newtonian F5, Skywatcher NEQ6 Mount, Altair Astro Hypercam, Celestron X CEL 3x Barlow Lens.
Clavius by Andrew Relf, Basildon, UK. Equipment: Skywatcher 200p, gp cam mono v1, 3x Barlow
Clavius by Andrew Relf, Basildon, UK. Equipment: Skywatcher 200p, gp cam mono v1, 3x Barlow
Panorama around Clavius by Houssem Ksontini, Tunisia. Equipment: Skywatcher 150/750, Neq3-2 mount, Barlow x3, IR Filter Astronomik 642 BP
Panorama around Clavius by Houssem Ksontini, Tunisia. Equipment: Skywatcher 150/750, Neq3-2 mount, Barlow x3, IR Filter Astronomik 642 BP
Clavius et Maginus by Houssem Ksontini, Tunis, Tunisia. Equipment: Skywatcher 150/750, Neq3-2 mount RA motorised, ASI224 MC, IR Pass Filter, Barlow x3
Clavius et Maginus by Houssem Ksontini, Tunis, Tunisia. Equipment: Skywatcher 150/750, Neq3-2 mount RA motorised, ASI224 MC, IR Pass Filter, Barlow x3
Eyes of Clavius by Avani Soares, Parsec Observatory, Canoas, Brazil. Equipment: C14 Edge, ASI 224, Powermate 2X, L filter
Eyes of Clavius by Avani Soares, Parsec Observatory, Canoas, Brazil. Equipment: C14 Edge, ASI 224, Powermate 2X, L filter
Sunset over Clavius by Harvey Scoot, Essex, UK. Equipment: C14 Edge HD, Altair Astro 178C Hypercam.
Sunset over Clavius by Harvey Scoot, Essex, UK. Equipment: C14 Edge HD, Altair Astro 178C Hypercam.
The Lunar South by John Brady, UK. Equipment: Skywatcher 200p, DMK41 mono CCD
The Lunar South by John Brady, UK. Equipment: Skywatcher 200p, DMK41 mono CCD
Lunar South Pole by Avani Soares, Parsec Observatory, Canoas, Brazil. Equipment: C14 Edge, ASI 290, IR 685
Lunar South Pole by Avani Soares, Parsec Observatory, Canoas, Brazil. Equipment: C14 Edge, ASI 290, IR 685
The Moon by Barry Godwin, Cheltenham, UK. Equipment: Canon 1100d, Celestron Nexstar 6se, 1.8 x barlow lens.
The Moon by Barry Godwin, Cheltenham, UK. Equipment: Canon 1100d, Celestron Nexstar 6se, 1.8 x barlow lens.
Moon by Ronald Piacenti Junior, Brasilia, DF, Brazil. Equipment: Celestron C6, HEQ5 Pro mount, Expanse ASI 120 MC CMOS camera.
Moon by Ronald Piacenti Junior, Brasilia, DF, Brazil. Equipment: Celestron C6, HEQ5 Pro mount, Expanse ASI 120 MC CMOS camera.
First Moon by John Wilkinson, Tamworth, UK. Equipment: Skywatcher 130
First Moon by John Wilkinson, Tamworth, UK. Equipment: Skywatcher 130
Daytime Southern Highlands by Craig Towell, Bristol, UK. Equipment: Fullerscopes 8.75
Daytime Southern Highlands by Craig Towell, Bristol, UK. Equipment: Fullerscopes 8.75″ f7.5 Newtonian, Baader Classic Ortho 10mm, Samsung Galaxy S8