FACT SNACK
December 21
How Big the Moon?
- How Big Is It? Bigger than Mercury and Pluto.
- So big that it's three and a half times the size of our moon ~ 3273 miles across.
- By volume, it's a little bigger than Mercury, and about half the size of Mars.
- In fact, if Ganymede orbited the Sun instead of orbiting Jupiter, it would be classified as a planet instead of a moon.
It's What's Inside That Counts. Ganymede has a metallic core 250~800 miles in. The core supports a magnetic field, an ice and silicate mantle, and a thick crust that is probably a thick layer of water ice.
Breathe Deep. Ganymede has a thin oxygen atmosphere that is produced by high-energy particles that break up surface water molecules.
Great Moons in History. Voyager images of Ganymede show a complex geological history. Its surface is a mixture of two types of terrain: highly cratered dark regions and a light grooved terrain that forms intricate patterns across Ganymede.
In the Groove. This grooved terrain was probably caused by tensional faulting or the release of water from beneath the surface. Two thousand foot-high ridges have been observed and the grooves run for hundreds of miles across Ganymede's surface.
The Dark Side. The dark regions on Ganymede are old and rough. The dark cratered terrain is thought to be Ganymede's original crust. Lighter regions are young and smooth, unlike those on our moon.
Word of the Day. The term sulcus, meaning a groove or burrow, is often used to describe the grooved features of Ganymede.
Ganymede Highlights. The largest area on Ganymede ~ Galileo Regio ~ is one of the areas targeted by the Galileo spacecraft.
Who Was Ganymede? A Trojan boy of great beauty. Zeus carried him away to be a cup bearer for the gods.
Earthling Discoverer. Ganymede was discovered by Galileo and Marius in 1610.
Link for More.