Ganymede
Ganymede is the largest moon of Jupiter and the solar system's largest satellite, surpassing even the planet Mercury in diameter. Here are some detailed facts about Ganymede:
Discovery
Physical Characteristics
- Size: With a diameter of 5,268 km, Ganymede is larger than the planet Mercury, although its mass is significantly less due to its lower density.
- Composition: Ganymede is composed of roughly equal parts of silicate rock and water ice, with a small iron core.
- Atmosphere: It has a thin oxygen atmosphere, which is too sparse to sustain life as we know it. This atmosphere is thought to be sourced from the sublimation of its icy surface due to radiation bombardment from Jupiter's magnetosphere.
- Surface Features: The surface of Ganymede is a mix of two types of terrain:
- Dark, heavily cratered regions similar to Callisto.
- Lighter regions with grooved terrain, indicating tectonic activity in its past.
- Magnetic Field: Ganymede is the only moon known to have its own magnetic field, which is believed to be generated by a molten iron core.
Orbital Characteristics
- Ganymede orbits Jupiter at an average distance of about 1.07 million kilometers and completes one orbit every 7.15 Earth days.
- Its orbit is locked in a 1:2:4 resonance with Europa and Io, meaning for every orbit Ganymede makes, Europa completes two orbits, and Io completes four.
Exploration
- Several spacecraft have visited Ganymede, most notably:
- Voyager 1 and Voyager 2, which flew by in 1979, providing the first detailed images of its surface.
- The Galileo spacecraft orbited Jupiter from 1995 to 2003 and made numerous flybys of Ganymede, mapping its surface in detail.
- Future missions like JUICE (JUpiter ICy moons Explorer) by ESA, set to launch in 2022, will focus on Ganymede, Europa, and Callisto.
Scientific Interest
- Scientists are particularly interested in Ganymede due to its potential subsurface ocean, which might be warm enough to support life.
- The interaction between its own magnetic field and Jupiter's magnetosphere also makes it a unique study case for planetary magnetism.
External Links
Related Topics