Janssen (lunar crater)
lunar impact crater
Janssen is an ancient impact crater located in the highland region near the southeastern lunar limb. It dates to the Pre-Nectarian period of the lunar geologic timescale. The entire structure has been heavily worn and is marked by many lesser crater impacts. The outer wall is breached in multiple locations, but the outline of the crater rim can still be observed. The wall forms a distinctive hexagonal shape upon the rugged lunar surface, with a slight curvature at the vertices.
The crater is named after French astronomer Pierre Jules César Janssen.
The prominent crater Fabricius lies entirely within the outer wall, in the northeast quadrant of the floor. A number of other lesser, but still notable craters mark the crater floor. Connected to the northeast rim is Metius, and to the north is the heavily worn Brenner. Southeast of Janssen are the co-joined craters Steinheil and Watt.
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The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Jun 19, 2026. The linked authority identifier is Q422126. Authority coordinates are -44.960, 40.820. 1 of 1 selected statements include explicit references; 0 carry qualifiers and 0 use preferred rank.
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This entry incorporates text from “Janssen (lunar crater)” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.