Help Shape the Future of Space Exploration

Join The Planetary Society Now  arrow.png

Join our eNewsletter for updates & action alerts

    Please leave this field empty

Headshot of Emily Lakdawalla

Door 3 in the 2010 advent calendar

Posted by Emily Lakdawalla

03-12-2010 16:20 CST

Topics: Jupiter's moons, pretty pictures, amateur image processing, Ganymede, Galileo

Time to open the third door in the advent calendar. Until the New Year, I'll be opening a door onto a different landscape from somewhere in the solar system. Where in the solar system is this wispy terrain?

Door 3

NASA / JPL-Caltech / color composite by Gordan Ugarkovic

Door 3
The image has a resolution of about 710 meters per pixel horizontally and 900 meters per pixel vertically, so it covers an area about 710 by 900 kilometers square.

This landscape is actually covered not with "wispy terrain" (that's found elsewhere in the solar system) but instead by "grooved terrain." And "groovy" is synonymous with "Ganymede," at least if you're a planetary geologist. Ganymede is, of course, Jupiter's largest moon -- the largest moon in the solar system, in fact. Galileo swung close to Ganymede on December 28, 2000 to capture the images for this observation of its surface.

Ganymede is a wonderful puzzle. It has two major types of terrain, "dark" and "light," both of which are visible here. The dark terrain is clearly older than the light terrain, because the grooves in the light terrain crosscut the dark terrain and because the dark terrain is more heavily cratered than the light terrain. But the story's much more complicated than that. In most places, the light terrain is sliced up by grooves that cross and cross and cross each other, so there's a detailed geologic history to be told by unraveling their interrelationships. And both are cratered, so these things happened a long time ago. It's taken many years to unravel this story; a definitive paper on the geologic history of Ganymede as revealed in maps of Galileo images appeared in Icarus earlier this year.

The images that Galileo took here were in green and violet wavelengths, so Gordan Ugarkovic created a synthetic red-filter image to make the color view.

The Planetary Society Blog 2010 Advent Calendar

See other posts from December 2010


Or read more blog entries about: Jupiter's moons, pretty pictures, amateur image processing, Ganymede, Galileo


Leave a Comment:

You must be logged in to submit a comment. Log in now.
Facebook Twitter Email RSS AddThis

Blog Search

Essential Advocacy

Our Advocacy Program provides each Society member a voice in the process.

Funding is critical. The more we have, the more effective we can be, translating into more missions, more science, and more exploration.


Featured Images

NGC 4100
The Flaming Star Nebula (IC 405)
LDN 604 and GGD 30
Schiaparelli backshell and parachute landing location from HiRISE in color
More Images

Featured Video

The Planetary Post - Carl Sagan's Pale Blue Dot

Watch Now

Space in Images

Pretty pictures and
awe-inspiring science.

See More

Join The Planetary Society

Let’s explore the cosmos together!

Become a Member

Connect With Us

Facebook, Twitter, YouTube and more…
Continue the conversation with our online community!