Marvelous Moondance: Jupiter Satellites Caught Eclipsing And Transiting

On Christmas Eve, as millions upon millions of people focused on wrapping gifts and getting ready for the holidays, an amateur astronomer gave a small gift to the world. The person turned a telescope and camera to Jupiter and caught volcanic Io going across the face of the gas giant. This happened just a few days after professional astronomers caught a rare eclipse involving that very same moon.

“I wish I had been able to go on for longer but Jupiter went behind the house just before the transit ended. The transit is 102 frames (306 captures in total, RGB separate). Seeing was rather poor and a small amount of dew formed resulting in reduced brightness and contrast in some parts of the GIF,” wrote Reddit user IKYLSP.

“Something rather interesting with this one is the brief appearance of Ganymede from behind the planet’s shadow just before it’s eclipsed by the planet. If you zoom in you can actually see it as a half-moon shape which is really awesome.”

Speaking of half-moons, check out another awesome animation of Io taken from the Gemini North observatory on Dec. 16. Here, you can see icy Europa passing in front of the volcanic moon from the telescope’s perspective. Here’s part of what the observatory wrote about the rare event:

Observations of Jupiter’s volcanically active moon Io, obtained that night as part of a program led by Katherine de Kleer of UC Berkeley to watch for volcanic outbursts, revealed an unusual event involving Io and another large jovian moon, Europa. According to de Kleer, the images captured an occultation event in which Europa briefly blocked some of the light from Io, “…giving Io a very un-Io-like appearance!” These sorts of events occur when we observe the moons’ orbits edge-on, and can occasionally view the moons passing in front of one another.

And below you can see individual frames from the eclipse.