Alder (crater)
impact crater on the Moon
Alder is a lunar impact crater that is located in the southern hemisphere on the far side of the Moon. It is located in the South Pole-Aitken basin, and lies to the southeast of the crater Von Kármán. Southeast of Alder is Bose, and to the south-southwest lies Boyle.
This crater dates from the Late Imbrian epoch, with an age of around ~3.5+0.01−0.2 Ga. The inner wall of Alder is rough and slightly terraced, with the material scattered across the edges of the otherwise relatively flat interior floor. There are several low central ridges lying along a band from the midpoint toward the eastern rim. A small crater lies on the eastern inner slopes. The crater is otherwise free of significant impacts within the rim.
The two small central mounds in Alder are similar in form but have distinctly different spectra. The mound to the west is strongly mafic, while the eastern mound shows more plagioclase.
The public source identifies “Alder (crater)” as impact crater on the Moon. This brief keeps that definition visible, then builds a research path around Alder, crater and impact.
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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 Jul 5, 2026. The linked authority identifier is Q1658702. Authority coordinates are -48.630, -177.880. 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 “Alder (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.