Sea / bay

Mare Humorum

The Sea of Moisture is a rounded dark plain in the southwestern near side. Gassendi marks its northern edge.

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Mare Humorum and surrounding lunar terrain in the LROC Wide Angle Camera mosaic
Mare Humorum · North up, east right. Open image ↗
NASA / GSFC / Arizona State University · LROC WAC mosaic via USGS. Regional map crop; lighting is fixed and does not follow the selected date.
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How to observe Mare Humorum

Trace the boundary between dark plain and bright highlands, then inspect Gassendi when its rim is near the terminator.

Finding the region

Look at 24.48° S, 38.57° W on the lunar disc. The chart marker identifies the catalogue centre. Start with a wide field and use the nearby formations below as landmarks.

Equipment & conditions

These dark plains are a good starting point with binoculars. Trace their shapes at low power, then examine the boundary with the brighter highlands. Higher sunlight helps reveal brightness differences; low sunlight brings out ridges.

Lighting

For surface relief, try a time when the Sun is low over this region. To compare surface brightness and any bright rays, return under higher illumination. The atlas calculates the solar elevation at the formation’s centre for any selected date.

View Mare Humorum in the atlas

IAU / USGS Gazetteer

Official feature record

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Approved name
Mare Humorum
Feature classification
Mare, maria
Catalogue dimension / extent
419.67 km
Centre latitude
24.48° S
Centre longitude
38.57° W
Name origin (Gazetteer)
"Sea of Moisture."

Coordinates are selenographic, with east-positive longitude. Dimensions are the Gazetteer’s catalogue values; for extended formations they do not represent a circular crater diameter. Data snapshot: 2026-09-16. Observing guidance above is separate from the official record.

Nearby formations

The four closest catalogue entries, measured from their centres.

LROC photograph of GassendiImpact crater

Gassendi

A large crater on the northern edge of Mare Humorum. Its floor contains central peaks and a network of fractures.

LROC photograph of Mare NubiumSea / bay

Mare Nubium

The Sea of Clouds is an irregular dark region south of the lunar equator. Partly buried formations and neighbouring highlands make its borders varied.

LROC photograph of SchickardImpact crater

Schickard

A broad walled plain in the southwestern lunar highlands. Different parts of its floor have noticeably different surface brightness.

LROC photograph of SchillerImpact crater

Schiller

A markedly elongated crater in the southwestern highlands. Its shape stands out among the more rounded neighbouring formations.