Menhit (crater)

Lore & Background

Menhit crater is located within an unnamed, bright terrain on Ganymede, southeast of the terminus of the bright terrain Sippar Sulcus. To its west lies the prominent ray crater Osiris, to its southwest the crater Thoth, to its south the surface depression Yaroun Patera, and to its east the craters Ashîma and Irkalla. Because Ganymede rotates synchronously, Menhit lies on the hemisphere that always faces away from Jupiter, meaning an observer at Menhit would never see Jupiter in the sky.

Menhit is probably a very old crater, based on how much of its original structure has disappeared. All that remains of its original rim are concentric zones of broken massifs and ridges surrounding the central dome. According to a study by Caussi, Dombard, Korycansky, White, Moore and Schenk, dome craters on Ganymede form when meltwater develops beneath craters after an impact, then refreezes and expands, pushing the crater floor upward to form a dome. Domes usually only form if a crater is more than 60 kilometers in diameter. The terrain surrounding Menhit rises approximately 500 metres above the surrounding plains, which is unusual because crater floors are normally at or below the elevation of the surrounding surface; the exact cause of this formation is not yet known.

Two pit craters of similar size overlap Menhit's rim on its northwest and southeast, almost perfectly diametrically opposite each other with respect to Menhit. Another dome crater comparable to Menhit in age and stage of formation is Neith, located on the opposite side of Ganymede.

Reader's Guide

Menhit's significance lies in its role as a well-studied example of a dome crater on an icy moon, providing insights into the geological processes that shape Ganymede's surface. The crater's advanced degradation and the presence of a central dome illustrate the long-term evolution of impact structures on icy bodies, where subsurface meltwater and refreezing can dramatically alter crater morphology. The unusual elevation of the terrain surrounding Menhit, rising 500 metres above the plains, challenges typical expectations for impact crater floors and remains unexplained. As of 2026, only Voyager 2 has imaged Menhit up close, during its July 1979 flyby of Ganymede's anti-Jovian hemisphere. The Galileo spacecraft captured only distant images, such as during a June 1996 flyby. The European Space Agency's Jupiter Icy Moons Explorer (Juice), scheduled to arrive at Jupiter in July 2031 and enter low orbit around Ganymede in 2034, is expected to obtain the first close-up images of Menhit, which could help planetary scientists better understand the nature and formation of dome craters on icy moons like Ganymede.

Did You Know?

• Menhit is named after a lion-headed goddess of war from Nubian mythology, later part of Egyptian mythology.
• The crater has a diameter of 140 kilometres (87 mi).
• Two unnamed pit craters overlap Menhit's rim on its northwest and southeast, nearly diametrically opposite each other.
• An observer at Menhit would never see Jupiter in the sky because it lies on Ganymede's anti-Jovian hemisphere.