We astronomers love a good list of objects to find!
Perhaps the most classic of them all is Charles Messier’s eponymous catalog of deep-sky objects. We can strive to find all 110 Messier objects in a single night, or we can take many months (or years) to complete our study.
The Lunar 100 was created in the same vein – it’s a challenge for those of us that love to point our telescopes at the moon.
There are some major differences between the Messier catalog and the lunar 100 though, other than their subject matter. The Lunar 100 was deliberately designed to get harder as you work through it, it can not be successfully completed in one night, and it’s open to everyone on the planet, no matter where you live.
In this article, we’re going to explain exactly what the Lunar 100 is, share the complete list with you, and give you the essential guide to seeing each of the one hundred features on the list.
What is the Lunar 100?
The Lunar 100 list was Created by Charles A. Wood for Sky & Telescope Magazine in 2004. He is well known in astronomy circles for writing the great book ‘The Modern Moon: A personal View‘ (link opens Amazon in a different tab).
Check out our other favorite books about the moon.
What Charles set out to achieve was an education about the complexities of the lunar surface. His list does this not by showing, necessarily, the ‘best’ features the moon has to offer our telescopes but by showing the diversity of what’s available.
He arranged the hundred lunar features in rough order of difficulty. We begin with the moon itself, followed by earthshine – the light we see from the dark moon which is reflected from Earth – before moving on to actual features.
By the time we hit the final 20 discoveries, we’re looking for tiny craters, barely visible domes, views that can only be seen during lunar librations, and magnetic swirls in the regolith.
The whole point is to discover the moon in more depth, almost like receiving 100 lessons from a very knowledgeable teacher.
The Lunar 100 List
The whole lunar 100 list is reproduced below. You can download it as a PDF at the bottom of this page, where you’ll also find our comprehensive guide to finding the Lunar 100.
|L||Feature||Significance||Lat. (°)||Long. (°)||Diam. (km)|
|L2||Earthshine||Twice reflected sunlight||–||–|
|L3||Mare/highland dichotomy||Two materials with distinct compositions||–||–|
|L4||Appenines||Imbrium basin rim||18.9N||3.7W||70|
|L5||Copernicus||Archetypal large complex crater||9.7N||20.1W||93|
|L6||Tycho||Large rayed crater with impact melts||43.4S||11.1W||85|
|L7||Altai Scarp||Nectaris basin rim||24.3S||22.6E||425|
|L8||Theophilus, Cyrillus, Catharina||Crater sequence illustrating stages of degradation||13.2S||24.0E||–|
|L9||Clavius||Lacks basin features despite its size||58.8S||14.1W||225|
|L10||Mare Crisium||Mare contained in large circular basin||18.0N||59.0E||540|
|L11||Aristarchus||Very bright crater with dark bands on its walls||23.7N||47.4W||40|
|L14||Sinus Iridum||Very large crater with missing rim||45.0N||32.0W||260|
|L15||Straight Wall||Best example of a lunar fault||21.8S||7.8W||110|
|L16||Petavius||Crater with domed and fractured floor||25.1S||60.4E||177|
|L17||Schroter’s Valley||Giant sinuous rille||26.2N||50.8W||168|
|L18||Mare Serenitatis dark edges||Distinct mare areas with different compositions||17.8N||23.0E||N/A|
|L19||Alpine Valley||Lunar graben||49.0N||3.0E||165|
|L21||Fracastorius||Crater with subsided and fractured floor||21.5S||33.2E||124|
|L22||Aristarchus plateau||Mysterious uplifted region mantled with pyroclastics||26.0N||51.0W||150|
|L23||Pico||Isolated Imbrium basin-ring fragment||45.7N||8.9W||25|
|L24||Hyginus Rille||Rille containing rimless collapse pits||7.4N||7.8E||220|
|L25||Messier & Messier A||Oblique ricochet-impact pair||1.9S||47.6E||11|
|L26||Mare Frigoris||Arcuate mare of uncertain origin||56.0N||1.4E||1600|
|L27||Archimedes||Large crater lacking central peak||29.7N||4.0W||83|
|L28||Hipparchus||First drawing of a single crater||5.5S||4.8E||150|
|L29||Ariadaeus Rille||Long, linear graben||6.4N||14.0E||250|
|L30||Schiller||Possible oblique impact||51.9S||39.0W||180|
|L31||Taruntius||Young floor-fractured crater||5.6N||46.5E||56|
|L32||Arago Alpha & Beta||Volcanic domes||6.2N||21.4E||26|
|L33||Serpentine Ridge||Basin inner-ring segment||27.3N||25.3E||155|
|L34||Lacus Mortis||Strange crater with rille and ridge||45.0N||27.2E||152|
|L35||Triesnecker Rilles||Rille family||4.3N||4.6E||215|
|L36||Grimaldi basin||A small two-ring basin||5.5S||68.3W||440|
|L37||Bailly||Barely discernible basin||66.5S||69.1W||303|
|L38||Sabine and Ritter||Possible twin impacts||1.7N||19.7E||30|
|L39||Schickard||Crater floor with Orientale basin ejecta stripe||44.3S||55.3W||227|
|L40||Janssen Rille||Rare example of a highland rille||45.4S||39.3E||190|
|L41||Bessel ray||Ray of uncertain origin near Bessel||21.8N||17.9E||N/A|
|L42||Marius Hills||Complex of volcanic domes & hills||12.5N||54.0W||125|
|L43||Wargentin||A crater filled to the rim with lava or ejecta||49.6S||60.2W||84|
|L44||Mersenius||Domed floor cut by secondary craters||21.5S||49.2W||84|
|L45||Maurolycus||Region of saturation cratering||42.0S||14.0E||114|
|L46||Regiomontanus central peak||Possible volcanic peak||28.0S||0.6W||124|
|L47||Alphonsus dark spots||Dark-halo eruptions on crater floor||13.7S||3.2W||119|
|L48||Cauchy region||Fault, rilles and domes||10.5N||38.0E||130|
|L49||Gruithuisen Delta and Gamma||Volcanic domes formed with viscous lavas||36.3N||40.0W||20|
|L50||Cayley Plains||Light, smooth plains of uncertain origin||4.0N||15.1E||14|
|L51||Davy crater chain||Result of comet-fragment impacts||11.1S||6.6W||50|
|L52||Cruger||Possible volcanic caldera||16.7S||66.8W||45|
|L53||Lamont||Possible buried basin||4.4N||23.7E||106|
|L54||Hippalus Rilles||Rilles concentric to Humorum basin||24.5S||29.0W||240|
|L55||Baco||Unusually smooth crater floor and surrounding plains||51.0S||19.1E||69|
|L56||Australe basin||A partially flooded ancient basin||49.8S||84.5E||880|
|L57||Reiner Gamma||Conspicuous swirl and magnetic anomaly||7.7N||59.2W||70|
|L58||Rheita Valley||Basin secondary-crater chain||42.5S||51.5E||445|
|L59||Schiller-Zucchius basin||Badly degraded overlooked basin||56.0S||45.0W||335|
|L60||Kies Pi||Volcanic dome||26.9S||24.2W||45|
|L61||Mosting A||Simple crater close to the center of the moon’s near side||3.2S||5.2W||13|
|L62||Rumker||Large volcanic dome||40.8N||58.1W||70|
|L63||Imbrium sculpture||Basin ejecta near and overlying Boscovich and Julius Caesar||11.0N||12.0E||–|
|L64||Descartes||Apollo 16 landing site; putative region of highland volcanism||11.7S||15.7E||48|
|L65||Hortensius domes||Dome field north of Hortensius||7.6N||27.9W||10|
|L66||Hadley Rille||Lava channel near Apollo 15 landing site||25.0N||3.0E||–|
|L67||Fra Mauro formation||Apollo 14 landing site on Imbrium ejecta||3.6S||17.5W||–|
|L68||Flamsteed P||Proposed young volcanic crater and Surveyor 1 landing site||3.0S||44.0W||112|
|L69||Copernicus secondary craters||Rays and craterlets near Pytheas||19.6N||19.1W||4|
|L70||Humboldtianum basin||Multi-ring impact basin||57.0N||80.0E||650|
|L71||Sulpicius Gallus dark mantle||Ash eruptions northwest of crater||19.6N||11.6E||12|
|L72||Atlas dark-halo craters||Explosive volcanic pits on the floor of Atlas||46.7N||44.4E||87|
|L73||Smythii basin||Difficult-to-observe basin scarp and mare||2.0S||87.0E||740|
|L74||Copernicus H||Dark-halo impact crater||6.9N||18.3W||5|
|L75||Ptolemaeus B||Saucer-like depression on the floor of Ptolemaeus||8.0S||0.8W||16|
|L76||W. Bond||Large crater degraded by Imbrium ejecta||65.3N||3.7E||158|
|L77||Sirsalis Rille||Procellarum basin radial rilles||15.7S||61.7W||425|
|L78||Lambert R||A buried “ghost” crater||23.8N||20.6W||54|
|L79||Sinus Aestuum||Eastern dark-mantle volcanic deposit||12.0N||3.5W||90|
|L80||Orientale basin||Youngest large impact basin||19.0S||95.0W||930|
|L81||Hesiodus A||Concentric crater||30.1S||17.0W||15|
|L82||Linne||Small crater once thought to have disappeared||27.7N||11.8E||2.4|
|L83||Plato craterlets||Crater pits at limits of detection||51.5N||9.4W||101|
|L84||Pitatus||Crater with concentric rilles||29.8S||13.5W||97|
|L85||Langrenus rays||Aged ray system||8.9S||60.9E||132|
|L86||Prinz Rilles||Rille system near the crater Prinz||27.0N||43.0W||46|
|L87||Humboldt||Crater with central peaks and dark spots||27.0S||80.9E||207|
|L88||Peary||Difficult-to-observe polar crater||88.6N||33.0E||74|
|L89||Valentine Dome||Volcanic dome||30.5N||10.1E||30|
|L90||Armstrong, Aldrin and Collins||Small craters near the Apollo 11 landing site||1.3N||23.7E||3|
|L91||De Gasparis Rilles||Area with many rilles||25.9S||50.7W||30|
|L92||Gylden Valley||Part of the Imbrium radial sculpture||5.1S||0.7E||47|
|L93||Dionysius rays||Unusual and rare dark rays||2.8N||17.3E||18|
|L94||Drygalski||Large south-pole region crater||79.3S||84.9W||162|
|L95||Procellarum basin||The Moon’s biggest basin?||23.0N||15.0W||3200|
|L96||Leibnitz Mountains||Rim of South Pole-Aitken basin||85.0S||30.0E||–|
|L97||Inghirami Valley||Orientale basin ejecta||44.0S||73.0W||140|
|L98||Imbrium lava flows||Mare lava-flow boundaries||32.8N||22.0W||–|
|L99||Ina||D-shaped young volcanic caldera||18.6N||5.3E||3|
|L100||Mare Marginis swirls||Possible magnetic field deposits||18.5N||88.0E||–|
How to Find All 100 Features
The first step, of course, is to have the list at your side. You can download the PDF version using the link at the bottom of this article.
On its own, unless you’re comfortable with the lunar coordinate system, the list is not hugely helpful for actually finding the objects. For that, you’re going to need a visual guide.
Then, of course, you could invest in a lunar map. As the name suggests, this is a map of the moon. I have owned one for many years and it is a great guide, but plotting 100 different features onto it to then find is not so simple.
What none of these options give you is a clear, unambiguous guide to the details and location of each individual feature. That’s why we developed the Guide to the Lunar 100.
Guide to The Lunar 100
Our guide to the Lunar 100 comes with everything you’ll need to successfully find, observe, and record all 100 challenges on the list. That includes a guide to the best nights to see each of the one hundred targets based on the moon’s phase.
Perhaps the most useful element though is the detailed, annotated NASA images of the lunar surface. Four whole-moon maps show the lunar surface at waxing crescent, first quarter, last quarter, and waning crescent, so you can see which features are best observed at which time.
Each of those four whole-moon images is then zoomed into with a further 14 detailed maps. See an example of a whole moon map and a zoomed-in area so you can see the detail and precision of what’s included in the guide. Click on each image to see a full-size version.
In total, there are 18 high-definition lunar maps with precise locations for all features clearly marked.
Some of the later features in the list are dastardly and even these detailed maps might not make it clear enough what you are searching for. That’s why we also included more detailed guidance for each feature on a printable PDF. Using the PDF with the maps means you’ll quickly discover exactly the right feature every time.
Finally, you’ll need somewhere to record your lunar voyage of discovery, which is why our guide contains printable recording sheets. You can note when and how you discovered each feature as you go.
If you’re ready to take on this epic challenge, click here to purchase our low-priced Guide to the Lunar 100.
Chasing down the Lunar 100 is an epic challenge that any of us can take on, no matter where in the world we live, or even if we do our astronomy in an urban area.
You will need a telescope to complete the whole list. Binoculars will show many of the larger features, and a small telescope reveals almost everything else. However, for the most intricate areas, you’ll need a 6″ model to reveal the fine structures, small hills, and tiniest craters.
However you tackle the Lunar 100, let our guide help you, and have fun!
Click the button below to download the whole Lunar 100 list as a PDF.