Thoth (crater)

This article is about the crater. For the Egyptian god, see Thoth.
Thoth
An image of Thoth crater, taken by Voyager 2 on 9 July 1979.
Feature typePit crater
Coordinates43°13′S 147°15′W / 43.22°S 147.25°W / -43.22; -147.25
Diameter102 kilometres (63 mi)[1]
EponymThoth

Thoth is a crater on Ganymede, the largest moon of Jupiter. The crater is approximately 102 kilometres (63 mi) wide[1] and it has a pit at its center which is quite common on Ganymede.

Naming

Thoth is named after the ibis-headed Egyptian deity Thoth, the god of wisdom, learning, and writing. According to the Ogdoad tradition of Ancient Egyptian belief, in the beginning of time, Thoth created himself and then he used his magical words to create the universe. He is credited as the inventor of writing and mathematics and was also considered the mediator of disputes between the gods, as well as the one who records the judgment of people after death on behalf of Osiris, the ruler of the Egyptian afterlife.[2]

The International Astronomical Union (IAU), the organization responsible for formally naming surface features on celestial bodies, chose the name Thoth in accordance with the convention specifying that craters on Ganymede are to be named after deities, heroes, or places from Ancient Middle Eastern mythology.[3] Ancient Egyptian mythology is traditionally considered one of the Middle Eastern mythologies.

The IAU approved the name for Thoth in 1985.[1]

Location

Thoth is located at mid-latitudes in the southern hemisphere of Ganymede.. The area in Thoth's vicinity is populated by different kinds of craters. To its west lies the prominent ray crater Osiris which dominates the region.[4]

To the northeast is the crater Menhit, while to the southeast is a surface depression called Yaroun Patera, which is a possible ground-level cryovolcano. Another ray crater called Andjeti lies to the southeast.[4]

Thoth is situated within the Osiris quadrangle (or section) of Ganymede (designated Jg12).[5]

Thoth is located on the hemisphere of Ganymede that never faces Jupiter as a result of the moon's synchronous rotation. From this location, Jupiter would never be visible in the sky.[a]

Morphology and Geology

Thoth is a crater with a pit at its center. This crater morphology is rare on rocky bodies like the Moon or planet Mercury, but common on icy moons like Ganymede.[7] It is believed that this is due to the nature of Ganymede's crust being made of water ice. Central pits form when heat from an asteroid impact generates meltwater beneath the crater floor. As this water refreezes, it expands—because water increases in volume upon freezing—fracturing and weakening the floor and causing it to collapse into a sinkhole-like pit, often near the center of the crater. These pit craters may continue to evolve if meltwater persists below the surface, as repeated freezing and expansion can eventually uplift the pit into a dome, similar to the one found in the nearby Osiris crater.[8]

Thoth does not have any crater rays, unlike the nearby ray craters Osiris and Andjeti. The exact reason for this is not yet fully known, but it is possible that Thoth is a much older crater that has lost its rays long ago due to space weathering. Some of the extensive bright rays and secondary craters from Osiris coat portions of Thoth's structure, strongly indicating that Osiris is more recent than Thoth.[8]

Exploration

Voyager 2 was the first spacecraft to image the side of Ganymede that never faces Jupiter during its flyby in July 1979. Owing to its slightly southward trajectory during the encounter with Jupiter and Ganymede, the probe captured high-quality images of the regions surrounding Thoth.[9]

The Galileo probe was the next—and, as of 2026, the most recent—spacecraft to observe Thoth while orbiting Jupiter between December 1995 and September 2003. However, it imaged Thoth crater only from a distance, and no high-resolution images of the crater are available in its image archive.

Future Missions

The European Space Agency's (ESA) Jupiter Icy Moons Explorer (Juice) is scheduled to arrive at Jupiter in July 2031.[10] After performing several flybys of Europa, Ganymede, and Callisto while orbiting Jupiter for three and a half years, Juice is set to enter a low orbit around Ganymede at a distance of just 500 kilometres (310 mi) in July 2034.[11] The probe is expected to return clear images of Thoth.

See also

Notes

  1. ^ For moons in synchronous rotation, such as Ganymede, 0° longitude corresponds to the part of the surface that always faces Jupiter. Regions between 90° W and 270° W longitude never face the moon's parent planet.[6]

References

  1. ^ a b c "GANYMEDE - Thoth". USGS. 2015. Retrieved 2026-01-27.
  2. ^ "Thoth Egyptian god". Britannica. 2026. Retrieved 2026-01-29.
  3. ^ "Categories (Themes) for Naming Features on Planets and Satellites". USGS. 2025. Retrieved 2026-01-27.
  4. ^ a b Schenk, Paul, ed. (2012). Atlas of the Galilean Satellites. Cambridge University Press. p. 165. doi:10.1017/CBO9780511676468. ISBN 9780511676468.
  5. ^ Ganymede Map Images Archived 2007-11-19 at the Wayback Machine
  6. ^ "Discussion of Chapter 6". Open University. Retrieved 2026-01-17.
  7. ^ "Isis Ganymede, Jupiter". Lunar and Planetary Institute. 1997.
  8. ^ a b Caussi, Michael; Dombard, Andrew; Korycansky, David; White, Oliver; Moore, Jeffrey; Schenk, Paul (2024-06-27). "Dome Craters on Ganymede and Callisto May Form by Topographic Relaxation of Pit Craters Aided by Remnant Impact Heat". Journal of Geophysical Research: Planets. 129 (7) e2023JE008258: 1–19. arXiv:2403.15653. Bibcode:2024JGRE..12908258C. doi:10.1029/2023JE008258. Retrieved 2026-01-29.
  9. ^ "Eyes in the Solar System". NASA. 2026. Retrieved 2026-01-27.
  10. ^ "Juice Jupiter Icy Moons Explorer". ESA. 2023. Retrieved 2026-01-29.
  11. ^ "Juice's journey and Jupiter system tour". ESA. 2022. Retrieved 2026-01-29.
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