How to observe a quarter Moon

The definition of a quarter Moon, best features to see on the surface, and images captured by astrophotographers.

Moon by Nick, Milan, Italy. Equipment: Canon 760, 300mm lens.

A first quarter Moon may sound like something of a misnomer to beginner lunar observers who note that, rather than being a quarter-lit as the name might suggest, the Moon appears half-lit.

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Similarly, towards the end of the lunar month, the ‘last quarter Moon’ phase may cause similar consternations. Last quarter? what happened to the 2nd and 3rd quarters?

During the phases of the Moon, the first quarter marks the point a quarter of the way through the entire lunar cycle.

And, when you think about it, the side of the Moon we’re seeing is a quarter lit, because we are seeing one half of the Moon, half-illuminated.

First Quarter Moon by Tom Chitson, Woking, Surrey, UK. Equipment: Sky Watcher Evostar 80ED, Nikon D3000, EQ3-2 Mount
First Quarter Moon by Tom Chitson, Woking, Surrey, UK. Equipment: Sky Watcher Evostar 80ED, Nikon D3000, EQ3-2 Mount

In contrast, the last quarter Moon occurs towards the end of the lunar cycle and marks the final stage of the waning phase, taking us from full Moon back to new Moon.

The terms first quarter and last quarter probably make more sense if we go through the phases of the Moon, bit by bit.

The whole lunar cycle lasts around 29 days, and during that time it passes through several stages.

The phases of the Moon. Credit: Yaorusheng / Getty Images
The phases of the Moon. Credit: Yaorusheng / Getty Images

During a lunar month, the Moon goes from new Moon, through the waxing crescent phase up to first quarter when the Moon’s disc appears half illuminated.

As more of the Moon is illuminated by the Sun beyond the halfway point on the lunar disc, this is known as the waxing gibbous phase, which progresses until full Moon, when the lunar disc is fully illuminated.

Then, the cycle reverses and goes from full Moon, through a waning gibbous phase until last quarter when, again, the lunar disc is half-illuminated (but this time on the opposite side).

Slowly, less and less of the Moon’s disc is illuminated during the waning crescent phase, until we’re back to new Moon and the cycle begins again.

First quarter takes place around day 7 of the lunar month, and last quarter around day 22.

Last Quarter Moon by Andrew McNaught, Gloucestershire, UK. Equipment: Sky-watcher ST102 Refractor, i-Nova NNB Cx OSC CCD, Skywatcher EQ8 Mount.
Last Quarter Moon by Andrew McNaught, Gloucestershire, UK. Equipment: Sky-watcher ST102 Refractor, i-Nova NNB Cx OSC CCD, Skywatcher EQ8 Mount.

Observing a quarter Moon

There’s lots to see on the Moon during the first quarter. Unlike during a full Moon, the terminator (the line marking the division between the lit and unlit sides of the Earth-facing lunar disc) is visible, splitting the side of the Moon we see right down the middle.

Shadows thrown onto the lunar surface at and around the terminator make some of the Moon’s craters and other surface features like lunar Maria really stand out, making this a great time to get out a pair of binoculars or a telescope and observe the lunar surface.

Let’s take a look at some of the best features to see during first quarter and last quarter.

For advice on exploring the Moon with the naked eye, binoculars or a telescope – whatever the phase – read our guides on how to observe the Moon and the best features on the Moon.

First quarter

There’s a range of features to see on a first quarter Moon.

Near the middle of the Moon is Hipparchus, a large, low-walled crater. The 150km- (94 mile) wide Hipparchus has another crater, Horrocks, within it near its northeastern rim.

South of Hipparchus is the 136km- (85 mile) wide crater Albategnius, with another crater (Klein) on its southwestern flank.

In the north, the vast Mare Imbrium – a plain over 1,120km wide – is beginning to show. In Latin, Mare Imbrium means ‘Sea of Showers’.

Plato and the Imbrium Sea by Mike Jennings, W. Yorkshire, UK. Equipment: Celestron C8 SCT, Advanced GT Mount, QHY5 CCD.
Crater Plato and Mare Imbrium by Mike Jennings, W. Yorkshire, UK. Equipment: Celestron C8 SCT, Advanced GT Mount, QHY5 CCD.

On its eastern edge you’ll find the 55km (34 mile) crater Aristillus, with the smaller (39km) crater Autolycus below it and the larger (57km) Cassini, above. They’re surrounded by mountain ranges.

To the south is Montes Apenninus, named after the Apennines in Italy. Due east is Montes Caucasus, and to the north is Montes Alpes.

Splitting the Montes Alpes is a 190km- (119 mile) long valley, Vallis Alpes.

It’s easy to spot with a small scope, but you’ll need a large (20cm) scope to see the narrow channel that winds along the valley floor.

The Moons Vallis Alpes. Credit: Pete Lawrence
Credit: Pete Lawrence

Last quarter

The last quarter phase of the Moon is wonderful, because there’s great contrast between the bright, rugged craters near the terminator and the dark, flat mare to the west.

Lunar sunset approaches the craters Ptolemaeus, Alphonsus, and Arzachel.

Plato and Vallis Alpes by David Ettie, Washington, Tyne and Wear, UK. Equipment: Celestron 9.25
Plato and Vallis Alpes by David Ettie, Washington, Tyne and Wear, UK. Equipment: Celestron 9.25″ SCT, Skywatcher HEQ5 Pro mount, Neximage 10.

Look to the north of the Moon at the vast Mare Imbrium. The craters and mountain peaks on its eastern side are stunning, especially the 101km (63 mile) crater Plato on the mare’s northernmost fringe.

Its dark, lava-flooded floor stands out against the surrounding bright lunar highlands. Use high magnification to look for shadows cast by Plato Crater’s walls onto its floor.

Can you spot the clair-obscur effect known as Plato’s Hook? This trick of the light is best seen one day after first quarter.

Due south of Plato, standing alone in Imbrium, is Mons Pico, a 2,400m (8,000ft) mountain. It’s only about the same height as the lower peaks of the Italian Dolomites.

But when the angle of light is low, Mons Pico stands out superbly, casting a long shadow onto the Mare Imbrium.

The Moon's Mons Pico. Credit: Pete Lawrence
Credit: Pete Lawrence

South of Mons Pico is the largest crater in Mare Imbrium – the dark-floored 83km (52 mile) Archimedes. Look out for the triangular promontory that extends from the southeast edge of its walls.

To the northeast of Mare Imbrium is Montes Alpes. Watch the terminator as it moves across this mountain range. As the valleys plunge into darkness, the peaks remain lit.

Pictures of the quarter Moon

Below is a selection of images of the Moon at and around the quarter phases, captured by astrophotographers and BBC Sky at Night Magazine readers.

For lunar imaging advice, read our beginner’s guide to astrophotography or our dedicated tutorial on how to photograph the Moon.

Or if sketching is more your thing, read our guide on how to draw the Moon.

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

The Moon by Steve Judge, Manchester, UK. Equipment: Sky-Watcher 150P Newtonian Reflector, Canon EOS 500D, EQ3 mount.
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The Moon by Steve Judge, Manchester, UK. Equipment: Sky-Watcher 150P Newtonian Reflector, Canon EOS 500D, EQ3 mount.

Moon Mosaic by Darren Carver, Manchester, UK. Equipment: Nexstar 8 GPS, wedge mount, Canon EOS 1000d
Moon Mosaic by Darren Carver, Manchester, UK. Equipment: Nexstar 8 GPS, wedge mount, Canon EOS 1000d
Half Way by Matt, Dudley, UK. Equipment: Chinese 8
Half Way by Matt, Dudley, UK. Equipment: Chinese 8″ reflector, Fujifilm Finepic S 2800 HD
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A “Blue” Moon by Jason Meadows, Kent, UK. Equipment: Bresser Messier N-150, 25mm eyepiece, Barlow x2, Panasonic Lumix TZ5
Moon by Michael Fennings, London, UK. Equipment: Celestron 130EQ/MD, Phillips SPC800(flashed to SPC9800).
Moon by Michael Fennings, London, UK. Equipment: Celestron 130EQ/MD, Phillips SPC800(flashed to SPC9800).
Moon by David Burr, Wimborne, UK. Equipment: Canon 450d, Adapter
Moon by David Burr, Wimborne, UK. Equipment: Canon 450d, Adapter
First Quarter Moon by Tom Chitson, Woking, Surrey, UK. Equipment: Sky Watcher Explorer 130p, EQ2 Mount, Sony Cybershot W210i.
First Quarter Moon by Tom Chitson, Woking, Surrey, UK. Equipment: Sky Watcher Explorer 130p, EQ2 Mount, Sony Cybershot W210i.
Waxing Moon by Simon Hurrell, West Berkshire, UK. Equipment: Celestron 127SLT, Flashed SPC880NC, IR Filter, Astro engineering focal reducer.
Waxing Moon by Simon Hurrell, West Berkshire, UK. Equipment: Celestron 127SLT, Flashed SPC880NC, IR Filter, Astro engineering focal reducer.
First Quarter Moon by Michael Fennings, London, UK. Equipment: Celestron 130EQ, Phillips 880 (flashed to 9800).
First Quarter Moon by Michael Fennings, London, UK. Equipment: Celestron 130EQ, Phillips 880 (flashed to 9800).
First ever lunar shot by Raymond Burling, Isle of Dogs, London, UK. Equipment: Canon 550D, SW80ED (Prime Focus)
First ever lunar shot by Raymond Burling, Isle of Dogs, London, UK. Equipment: Canon 550D, SW80ED (Prime Focus)
Moon by Alan Mcgough, Manchetser, UK. Equipment: Skywatcher Skymax 127 5
Moon by Alan Mcgough, Manchetser, UK. Equipment: Skywatcher Skymax 127 5″ Maksutov, Canon 1000d.
Misty Moon by Danny Lee, Kent, UK. Equipment: Skywatcher 150p, EQ5 PRO GOTO, Nikon D40 at prime focus
Misty Moon by Danny Lee, Kent, UK. Equipment: Skywatcher 150p, EQ5 PRO GOTO, Nikon D40 at prime focus
Moon by Joseph Broadhurst, Telford, Shropshire, UK. Equipment: LX 90 Schmidt Cassegrain 8
Moon by Joseph Broadhurst, Telford, Shropshire, UK. Equipment: LX 90 Schmidt Cassegrain 8″, Canon EOS 1000D
The Moon by Wayne Stallard, Essex, UK. Equipment: EQ6 PRO Mount, William Optics FLT132, Tele-Vue 2x Power Mate, Canon 400d.
The Moon by Wayne Stallard, Essex, UK. Equipment: EQ6 PRO Mount, William Optics FLT132, Tele-Vue 2x Power Mate, Canon 400d.
The Moon by Kiren Billaney, Beverley, UK. Equipment: Nikon Coolpix L120
The Moon by Kiren Billaney, Beverley, UK. Equipment: Nikon Coolpix L120
Half Moon by David Bennett, Belvedere, UK. Equipment: Celestron Astro Master 130EQ, 10mm lens, omni 2x barlow lens, Samsung ES28 camera
Half Moon by David Bennett, Belvedere, UK. Equipment: Celestron Astro Master 130EQ, 10mm lens, omni 2x barlow lens, Samsung ES28 camera
Waxing Gibbous by Jennie Dummett, South Wales, UK. Equipment: Skywatcher Skyliner 200P Dobsonian, DMC-FX33
Waxing Gibbous by Jennie Dummett, South Wales, UK. Equipment: Skywatcher Skyliner 200P Dobsonian, DMC-FX33
Half Moon by Russ Weymouth, Colchester, UK. Equipment: Skywatcher 190 Maksutov Newtonian, Canon EOS40D attached at prime focus.
Half Moon by Russ Weymouth, Colchester, UK. Equipment: Skywatcher 190 Maksutov Newtonian, Canon EOS40D attached at prime focus.
Half Moon by Martin Bailey, Gnosall, Staffs, UK. Equipment: Canon 1000D, Skywatcher 200PDS.
Half Moon by Martin Bailey, Gnosall, Staffs, UK. Equipment: Canon 1000D, Skywatcher 200PDS.
Moon by Stephen Dean, Isle of Wight, UK. Equipment: Skywatcher 80 mm ED pro, Canon 1100D.
Moon by Stephen Dean, Isle of Wight, UK. Equipment: Skywatcher 80 mm ED pro, Canon 1100D.
Half Moon by Ronan Monaghan, Belleek, N. Ireland. Equipment: Microsoft Lifecam Webcam, Skywatcher 150p
Half Moon by Ronan Monaghan, Belleek, N. Ireland. Equipment: Microsoft Lifecam Webcam, Skywatcher 150p
Moon 62.8% Illuminated in near Perfect Seeing by Steve Ward, Red Lodge, Suffolk, UK. Equipment: Canon EOS1000D, Skywatcher Mak180Pro.
Moon 62.8% Illuminated in near Perfect Seeing by Steve Ward, Red Lodge, Suffolk, UK. Equipment: Canon EOS1000D, Skywatcher Mak180Pro.
Lunar 166 Frame Mosaic by Wayne Stallard, Basildon, Essex, UK. Equipment: Astro-Physics Mach 1 GTO Mount, IKHAROS 10
Lunar 166 Frame Mosaic by Wayne Stallard, Basildon, Essex, UK. Equipment: Astro-Physics Mach 1 GTO Mount, IKHAROS 10″ RC SCOPE, Point Grey Flea3.
Another Early Morning Moon by Aprill Harper, Blunham, Bedfordshire, UK. Equipment: Samsung NX1000, SkyWatcher 8
Another Early Morning Moon by Aprill Harper, Blunham, Bedfordshire, UK. Equipment: Samsung NX1000, SkyWatcher 8″ Dobsonian.
Moon First Quarter taken at Wembley by Paul Licorish, Wembley, UK. Equipment: Celestron Nexstar 5Se, Canon 650D, Variable Polarizer
Moon First Quarter taken at Wembley by Paul Licorish, Wembley, UK. Equipment: Celestron Nexstar 5Se, Canon 650D, Variable Polarizer
Moon by David Hallam. Equipment: Celestron Nexstar SLT127, Cannon EOS 1100
Moon by David Hallam. Equipment: Celestron Nexstar SLT127, Cannon EOS 1100
Moon by David Hallam. Equipment: Celestron Nexstar SLT127, Cannon EOS 1100
Moon by David Hallam. Equipment: Celestron Nexstar SLT127, Cannon EOS 1100
Moon by Richard Preston Lawford, Margate, UK. Equipment: Sony DCS-H300, tripod
Moon by Richard Preston Lawford, Margate, UK. Equipment: Sony DCS-H300, tripod
My first lunar mosaic!! by Roshaan Bukhari, Lahore, Pakistan. Equipment: Meade 70mm Refractor, Orion StarShoot Planetary Camera.
My first lunar mosaic!! by Roshaan Bukhari, Lahore, Pakistan. Equipment: Meade 70mm Refractor, Orion StarShoot Planetary Camera.
Moon Shot by John O'Mahony, Sydney, NSW. Equipment: Canon 7D, Meade 8
Moon Shot by John O’Mahony, Sydney, NSW. Equipment: Canon 7D, Meade 8″SCT.