A guide to the Moon’s Tycho Crater

Our complete guide to Tycho Crater, including images of the lunar feature and the best time to observe it.

Mosaic of Tycho by Stephen Heliczer, London, UK. Equipment: ASI120 CCD, Celestron Evolution 8.

For part of each lunation, Tycho Crater is perhaps the most conspicuous feature on the entire Moon.

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It is named after Tycho Brahe (1546-1601), the Danish astronomer whose measurements of the movements of Mars enabled Johannes Kepler to show that the planets’ orbits are elliptical, not circular.

Tycho crater has a high, continuous wall and a prominent central peak, but what distinguishes it is its unrivalled system of bright rays, which extend outward from the crater in all directions, covering an area of over 550,000 square km and containing dense clusters of small secondary craterpits.

Crater Tycho, as seen by the Hubble Space Telescope. Credit: NASA, ESA, and D. Ehrenreich (Institut de Planétologie et d'Astrophysique de Grenoble (IPAG)/CNRS/Université Joseph Fourier)
Crater Tycho, as seen by the Hubble Space Telescope. Credit: NASA, ESA, and D. Ehrenreich (Institut de Planétologie et d’Astrophysique de Grenoble (IPAG)/CNRS/Université Joseph Fourier)

Facts about Tycho crater

  • Size: 86km
  • Age: A little more than 100 million years
  • Location: Latitude 43.3°S, longitude 11.2°W
  • Recommended observing equipment: 4-inch telescope

At sunrise Tycho looks like a normal crater, and is a superb sight with its floor partly in shadow and sunlight catching the central peak.

But before long the rays come into view, and near full Moon they dominate the whole scene, covering all the features they cross, and making even large craters difficult to identify.

In fact, full Moon is the worst time for a beginner to start observing. The longest rays stretch for up to 1,500km.

For advice on the best time to take a look at our celestial neighbour, read our guide on how to observe the Moon.

A comparison between crater Tycho and the Shard. Credit: NASA Goddard/Arizona State University
A comparison between crater Tycho and London’s Shard. Credit: NASA Goddard/Arizona State University

Tycho lies in the southern uplands, and often gives the impression of being a polar crater, though in fact it lies well clear of the libration zone and is only slightly foreshortened.

The fact that the rays of Tycho overlie other features shows that the crater must be very young by lunar standards: perhaps the youngest of all the major craters. Its age is usually given as a little over 100 million years.

Remember, though, that at the time of the Tycho impact the most advanced life forms on Earth were jellyfish and the like.

It has been suggested that the impactor that produced Tycho was a broken-off fragment of the asteroid 298 Baptistina, and even that another fragment produced the Chicxulub crater 65 million years ago and led to the demise of the dinosaurs.

Theories of this kind are interesting, but highly speculative!

Tycho and Clavius Neil Barnes, Stourbridge, 4 April 2020. Equipment: GT-Vision GXCAM EYE5 camera, Altair Starwave Ascent 102ED f/7 refractor, Sky-Watcher HEQ5 Pro mount
Tycho and Clavius Neil Barnes, Stourbridge, 4 April 2020. Equipment: GT-Vision GXCAM EYE5 camera, Altair Starwave Ascent 102ED f/7 refractor, Sky-Watcher HEQ5 Pro mount

Tycho is in a crowded area; nearby large craters are Street, Pictet and Sasserides. However, it is always easy to spot because of its bright walls and regular shape.

When the rays come into view they seem to extend from the walls rather than the peak in the centre.

The ramparts beyond the rim are darker than the floor out to a distance of at least 100km, and are ray-free. This duskier rim may consist of minerals dislodged during the impact.

During the next lunation I strongly recommend that you make a special study of Tycho, both by drawing it and photographing it.

Catch it as the first gleam of sunlight strikes it, and watch the slow emergence of the central peak; then come the rays, so that by the time of the full Moon, everything is swamped in the pool of light.

Tycho crater Steve Fox, Camberley, Surrey, 3 November 2020. Equipment: ZWO ASI 120MM mono camera, Celestron EdgeHD 9.25-inch Schmidt-Cassegrain,
Tycho crater by Steve Fox, Camberley, Surrey, 3 November 2020. Equipment: ZWO ASI 120MM mono camera, Celestron EdgeHD 9.25-inch Schmidt-Cassegrain,

Below is a selection of images of Tycho Crater captured by astrophotographers and BBC Sky at Night Magazine readers.

For advice on capturing a lunar image, read our guides on how to photograph the Moon and how to draw the Moon. And get to know the lunar calendar with our guide to the phases of the Moon.

To get weekly lunar phases delivered directly to your email inbox, sign up to the BBC Sky at Night Magazine newsletter.

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And if you do manage to photograph or sketch the moon, don’t forget to send us your images or share them with us via Facebook, Twitter and Instagram.

Tycho by Robin Buckmaster, Thrapston, UK. Equipment: Skywatcher 150PL Reflector, NexImage.
Tycho by Robin Buckmaster, Thrapston, UK. Equipment: Skywatcher 150PL Reflector, NexImage.
Clavius and Tycho by Alex Houston, Tullibody, Alloa, UK. Equipment: Skywatcher Evostar 100 ED2 PRO, DMK 41AU02.AS mono CCD, Antares 2x apochromatic Barlow lens, Baader Luminance filter
Clavius and Tycho by Alex Houston, Tullibody, Alloa, UK. Equipment: Skywatcher Evostar 100 ED2 PRO, DMK 41AU02.AS mono CCD, Antares 2x apochromatic Barlow lens, Baader Luminance filter
Tycho and the South West by Mike Jennings, W. Yorkshire, UK. Equipment: Celestron C8 SGT, QHY5 CCD.
Tycho and the South West by Mike Jennings, W. Yorkshire, UK. Equipment: Celestron C8 SGT, QHY5 CCD.
Blue Moon 3 - Tycho Crater by Adam Pettifer, Epsom, UK. Equipment: SkyWatcher 130p, EQ-2 mount, iPhone 4 camera, Instagram app filters.
Blue Moon 3 – Tycho Crater by Adam Pettifer, Epsom, UK. Equipment: SkyWatcher 130p, EQ-2 mount, iPhone 4 camera, Instagram app filters.
Tycho and Sea of Tranquility by Adam Pettifer, Epsom, Surrey, UK. Equipment: SkyWatcher 130p, EQ-2 mount, iPhone 4 camera.
Tycho and Sea of Tranquility by Adam Pettifer, Epsom, Surrey, UK. Equipment: SkyWatcher 130p, EQ-2 mount, iPhone 4 camera.
Craters Tycho & Clavius by Ralph Smyth, Lisburn, Co. Antrim. Equipment: Celestron C8 SCT, ASI 120mm CCD.
Craters Tycho & Clavius by Ralph Smyth, Lisburn, Co. Antrim. Equipment: Celestron C8 SCT, ASI 120mm CCD.
Clavius & Tycho by Alan Stewart, Glenrothes, UK. Equipment: Orion Starshoot IV
Clavius & Tycho by Alan Stewart, Glenrothes, UK. Equipment: Orion Starshoot IV
Crater Tycho by George Zealey, Herstmonceux, Sussex, UK. Equipment: Skywatcher 200PDS, QHY5 CCD, EQ5 PRO Mount
Crater Tycho by George Zealey, Herstmonceux, Sussex, UK. Equipment: Skywatcher 200PDS, QHY5 CCD, EQ5 PRO Mount
Clavius, Schiller, and Tycho by Luke Oliver, Bedford, UK. Equipment: Sky-Watcher Explorer 200P, ZWO ASI120MC CCD, 2x Barlow Lens, IR-Pass Filter.
Clavius, Schiller, and Tycho by Luke Oliver, Bedford, UK. Equipment: Sky-Watcher Explorer 200P, ZWO ASI120MC CCD, 2x Barlow Lens, IR-Pass Filter.
Tycho by Mark Whitcutt, Newport, Wales, UK. Equipment: Orion Planetary Camera, Skywatcher 120mm achromatic refractor.
Tycho by Mark Whitcutt, Newport, Wales, UK. Equipment: Orion Planetary Camera, Skywatcher 120mm achromatic refractor.
Mosaic of Tycho by Stephen Heliczer, London, UK. Equipment: ASI120 CCD, Celestron Evolution 8.
Mosaic of Tycho by Stephen Heliczer, London, UK. Equipment: ASI120 CCD, Celestron Evolution 8.
Tycho by Mark Whitcutt, Newport, UK. Equipment: Skywatcher 150pds reflector, Orion Planetary Camera
Tycho by Mark Whitcutt, Newport, UK. Equipment: Skywatcher 150pds reflector, Orion Planetary Camera
Southern Highland Area - Tycho & Clavius Region by Ralph Smyth, Lisburn, Co. Antrim. Equipment: Celestron C8 SCT, HEQ5PRO mount, ZWO 120 CCD, Baader longpass filter.
Southern Highland Area – Tycho & Clavius Region by Ralph Smyth, Lisburn, Co. Antrim. Equipment: Celestron C8 SCT, HEQ5PRO mount, ZWO 120 CCD, Baader longpass filter.
The always amazing Tycho! by Avani Soares, Parsec Observatory, Canoas, Brazil. Equipment: C14 Edge, ASI 224, Powermate 2X, L filter.
The always amazing Tycho! by Avani Soares, Parsec Observatory, Canoas, Brazil. Equipment: C14 Edge, ASI 224, Powermate 2X, L filter.
Tycho by Fred Connell, Huntley, UK. Equipment: Skywatcher 5
Tycho by Fred Connell, Huntley, UK. Equipment: Skywatcher 5″, Nikon J1 body, Mac.
Tycho by James Harrop, Bradford, UK. Equipment: Skywatcher 180mm Maksutov, ASI224MC CCD with sharpcap.
Tycho by James Harrop, Bradford, UK. Equipment: Skywatcher 180mm Maksutov, ASI224MC CCD with sharpcap.
Tycho Crater by Fernando Oliveira De Menezes, São Paulo, Brazil. Equipment: C11 edge HD, So 290mc, IR Filter PASS 685.
Tycho Crater by Fernando Oliveira De Menezes, São Paulo, Brazil. Equipment: C11 edge HD, So 290mc, IR Filter PASS 685.