Humbaba (crater)
Largest dark crater on Ganymede with a double halo.
Humbaba is a crater on Jupiter’s moon Ganymede, measuring about 40 km (25 mi) across. It features a dark ray system—an uncommon type of formation on Ganymede—and is the largest dark crater on the moon.
**Naming** The crater takes its name from Humbaba, a fearsome guardian of the gods’ cedar forest in Mesopotamian mythology. In the Epic of Gilgamesh, King Gilgamesh and his friend Enkidu, after a wrestling match that ended in a draw, set out to kill Humbaba to make their names legendary. The International Astronomical Union (IAU) requires that craters on Ganymede be named after deities, heroes, or places from ancient Middle Eastern mythology, including Mesopotamian tales. The name was approved in the year 2000.
**Location** Humbaba sits in Ganymede’s southern latitudes, about two-thirds of the way from the equator to the moon’s south pole. To its west lies Babylon Sulci, a region of grooved terrain, and to its east is Nicholson Regio, an old, dark area. It belongs to the Nabu crater quadrangle (designated Jg11), near the quadrangle’s southwestern corner. The crater is on the side of Ganymede that always faces Jupiter—due to the moon’s synchronous rotation—close to the subjovian point, where Jupiter always hangs overhead. From inside Humbaba, Jupiter would appear nearly directly above at all times.
**Morphology** The crater is about 40 km (25 mi) wide, with a dark interior and a distinctive double halo: dark ejecta surrounded by brighter ejecta. This makes it the widest dark crater on Ganymede. The origin of the dark material is debated. A study by Namitha Baby suggests the impactor excavated it from 3 to 5.6 km (1.9 to 3.5 mi) below the surface. In contrast, Dr. Paul Schenk’s research proposes that the dark material came from the impactors themselves, which spread it across the moon during the collision.
**Exploration** The Galileo spacecraft was the first to image Humbaba. During its mission orbiting Jupiter from December 1995 to September 2003, it flew past Ganymede multiple times. In June 1997, during a close encounter, Galileo captured high-resolution images of the crater and its surroundings. As of 2026, these remain the best views available.
**Future Missions** The European Space Agency’s Jupiter Icy Moons Explorer (Juice), launched in April 2023, is set to reach Jupiter in July 2031.
Quick Facts
- Diameter
- 40.0 km
- Eponym
- Humbaba
Facts from the source article.
Lore & Background
Humbaba is named after a mighty creature from Mesopotamian mythology who guarded the cedar forest of the gods. According to the Epic of Gilgamesh, King Gilgamesh and his friend Enkidu slew Humbaba to immortalize their names. The International Astronomical Union (IAU) approved the name in the year 2000, following its rule that craters on Ganymede be named after deities, heroes, and places from Ancient Middle Eastern mythology.
The crater is located in the southern latitudes of Ganymede, near the subjovian point—the point on the moon that always faces Jupiter due to synchronous rotation. To its west lies Babylon Sulci, and to its east is Nicholson Regio. It is part of the Nabu crater quadrangle (Jg11), near its southwestern corner.
Humbaba is approximately 40 km wide with a dark interior and a unique double halo configuration: dark ejecta material surrounded by bright ejecta. The source of the dark material is debated. A study by Namitha Baby suggests it was excavated from 3 to 5.6 km below the surface, while Dr. Paul Schenk's studies propose it originated from the impactors themselves.
Reader's Guide
Humbaba crater holds significance as the largest dark crater on Ganymede, a rare feature on the moon. Its dark ray system and double halo configuration make it a key subject for understanding Ganymede's surface composition and impact processes. The debate over the dark material's origin—whether excavated from depth or delivered by impactors—highlights ongoing questions about the moon's subsurface and the nature of impacting bodies. The Galileo spacecraft provided the first and, as of 2026, highest-quality images of Humbaba during a close encounter in June 1997. Future exploration by the European Space Agency's Juice mission, scheduled to enter low orbit around Ganymede in July 2034, is expected to return high-resolution images that may help resolve these questions. Humbaba's location near the subjovian point also offers a unique perspective for studying the moon's tidal locking and its relationship with Jupiter.
Did You Know?
- Humbaba is the largest dark crater on Ganymede, with a diameter of about 40 km.
- The crater exhibits a rare dark ray system and a double halo of dark ejecta surrounded by bright ejecta.
- The source of its dark material is debated: one study suggests it was excavated from 3 to 5.6 km below the surface, while another proposes it came from the impactors.
- An observer inside Humbaba would always see Jupiter almost overhead because the crater lies near Ganymede's subjovian point.
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