We are accustomed to see the moon in typical bright white with some dark patches. But have you ever thought what's the cause behind it ? The mystery has now come to an end. United States Geological Survey (USGS) has just released a comprehensive map to elucidate the surface geology of our planet's 4.53 billion years aged nearest neighbour.


The years-long hard toil of the scientists from USGS Astrogeology Science Center, in collaboration with NASA, and the Lunar Planetary Institute, finally results to a successful mapping of the entire geology of lunar surface (often called ‘lunar science’ or ‘selenology’) for the first-ever time. This map is called ‘Unified Geologic Map of the Moon’. It was released on 20th April 2020.

The above animation is showing a rotating globe of the new Unified Geologic Map of the Moon with shaded topography.

A Brief Description of the Map

USGS refered this map as ‘the definitive blueprint’ of the surface of moon that depicts the geology of the surface, rocks, stratigraphy in an ‘incredible detail’ which, no doubt, will be helpful for further mission to moon in future, as well as for other scientific researches. The digital map has prepared to a scale 1:5,000,000. This new unified geologic map has prepared in a orthographic projection, that has represented the 3-dimensional celestial object into a 2-dimensional map.

Orthographic projections of Unified Geologic Map of the Moon | Image Courtesy : USGS

Another presentation of the geologic map has done, where the two poles have shown in Polar Stereographic projection, and the equatorial and lower latitudinal regions through Mercator Projection.

Unified Geologic Map of the Moon | Image Courtesy : USGS Astrogeology

A total of forty-eight different map units with differently coloured map symbols, and six types of line symbols have been used in the map in order to picturesque explanation of the lunar topography.


Some geologic map units of the moon surface as shown in the above map are:

  • Copernican Crater
  • Eratosthenian Crater, Catena (Ecc)
  • Eratosthenian Mare (Em)
  • Imbrian Imbrium Apenninus Formation (Iiap)
  • Imbrian Orientale Hevelius Formation, Inner Facies (Iohi)
  • Nectarian Basin, Undivided (Nb)
  • pre-Nectarian Basin Massif (pNbm), and others.

The depicted six line symbols uded in map are:

  • Volcanic channel (rille)
  • Crest of buried crater rim
  • Crest of crater rim (hachures point inside crater)
  • Graben axis (dashed where approximate)
  • Lineament (ambiguous origins)
  • Wrinkle ridge crest (dashed where approximate)

Former NASA astronaut and present USGS Director Jim Reilly said,
“People has always been fascinated by the moon and when we might return. So, it is wonderful to see U.S.G.S. create a resource that can help NASA with their planning for various future missions.”

Corey Fortezzo, a USGS geologist and a lead author of this study, stated that,
“This map is a culmination of a decades-long project. It provides many essential information for new scientific studies by connecting the exploration of specific sites on the moon with the rest of the lunar surface.”

The Missions Which Carried Out this Study

This newest digital map has been developed by merging and aligning the regional geologic maps devised by previous Apollo missions to the moon, with the newly acquired data by recent satellite missions. Besides this, the USGS geologists refined the previous inconsistent geologic map of moon, by replacing with more definite rock structure or stratigraphy of lunar surface.

Scientists have studied topography of lunar surface by dividing it in three divisions, viz. equatorial region, north pole, and south pole.
The exploration for the elevation data in the equatorial region has carried out by Japan Aerospace Exploration Agency’s SELENE (Selenological and Engineering Explorer) mission. In the other side, the observation of topography in the north and south pole of moon has led down by a robotic spacecraft of NASA, named as Lunar Orbitar Laser Altimeter (LOLA).

The data acquired and provided by LOLA, as reported by USGS, can also pick out the safe landing sites, locate potential resources on moon, defining radiation environment, and others.

For Further Studies and References :

Wikipedia | Geology of the Moon

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