When it comes to the multitude of moons that exist in our solar system, we often hear a lot about the few big stars of today’s scientific stage: Titan, Europa, Enceladus, Pluto’s most recently-discovered companions Kerberos and Styx, Mars’ moon Phobos… and of course our very own lovely moon, The Moon. But in the vast pantheon of heavenly satellites there’s one that looms above all the rest: Ganymede, the seventh moon of Jupiter and the largest moon in the entire solar system.
But just because Ganymede doesn’t make the headlines as often as its smaller cousins doesn’t mean it lacks fans in the scientific community, as evidenced by a brand-new geologic map released today by the USGS.
The comprehensive (and very colorful) map is the result of a project led by Geoffrey Collins of Wheaton College, and uses the most detailed images obtained of Ganymede by NASA’s Voyager 1 and 2 and Galileo spacecraft, executing imaging flybys of Jupiter and its moons in 1979, and the late 90s and early 2000s, respectively.
Using colors to differentiate the incredibly varied terrain on Ganymede, the illustrative map provides planetary scientists with the first solid evidence for distinct periods in the massive moon’s history: ancient, heavy cratering; tectonic upheaval; and then more recent settling and geologic decline.
Watch a 360-degree rotation of Ganymede and its new map below:
“This map illustrates the incredible variety of geological features on Ganymede and helps to make order from the apparent chaos of its complex surface,” said Robert Pappalardo of JPL. “This map is helping planetary scientists to decipher the evolution of this icy world and will aid in upcoming spacecraft observations.”
ESA’s upcoming Jupiter Icy Moons Explorer (JUICE) mission is slated to launch in 2022 and orbit Ganymede around 2032, and this map will undoubtedly aid in mission planning and the targeting of specific objectives.
The largest of Jupiter’s 63 named satellites, Ganymede has twice the mass of our moon and is even larger than the planet Mercury. In fact, at 3,280 miles wide Ganymede is bigger than Mercury and almost as large as Mars! Its complex icy surface is crisscrossed by dark regions covered with craters and lighter areas lined with grooves and ridges.
Ganymede even has a very thin oxygen atmosphere as well as its very own magnetosphere, generated by a molten core made up of heavy conductive metals. It’s been said that if Ganymede were to be orbiting the sun instead of Jupiter, it would easily be classified as a planet in its own right.
Discovered by Galileo in 1610, Ganymede is visible from Earth as one of the four Galilean moons seen alongside Jupiter (with Callisto, Io and Europa). With Jupiter so bright in the sky right now it’s fairly easy to spot Ganymede for yourself. All that’s needed is a small telescope or decent pair of binoculars (preferably mounted on a tripod) and a clear night sky… and a way to know what you’re seeing.
Source: NASA news release