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Emily Lakdawalla • Mar 26, 2018

#MoonMon: Io's pretty plumes

On this Moon Monday, I'm still catching up from the Lunar and Planetary Science Conference. So rather than dig into the data archives to make my own moon photo, I'm featuring an animation processed by Gordan Ugarkovic, showing Jupiter's volcanic moon Io with its prominent plumes. You can get a sense of how high the plumes reach above the surace as you watch Io rotate. The tops of the plumes rise from nighttime darkness into sunlight, so they remain visible on the night side of the moon.

Animation of Pele and Tvashtar's Plumes
Animation of Pele and Tvashtar's Plumes This animation, composed of UV3 frames from the Cassini Imaging Science Subsystem (ISS) taken on 2 January 2001 and magnified by a factor of 2, shows plumes from Io's Tvashtar and Pele Paterae (volcanoes).Image: NASA / JPL-Caltech / SSI / Gordan Ugarkovic
Animation of Tvashtar and Pele's Plumes
Animation of Tvashtar and Pele's Plumes This animation, composed of UV3 frames from the Cassini Imaging Science Subsystem (ISS) taken on January 2, 2001 and magnified by a factor of 2, shows plumes from Io's Tvashtar and Pele Paterae (volcanoes).Image: NASA / JPL-Caltech / SSI / Gordan Ugarkovic

When I first looked at these photos, I thought they were from New Horizons, which famously photographed Tvashtar erupting when it passed by Jupiter in 2007. But nope! It's Cassini! I had no idea Cassini had seen such dramatic plumes from Io. That's what you get when amateurs dig into archival data!

One note about these images: they're taken through an ultraviolet filter. Io looks quite different in an ultraviolet filter than it does in a clear (broadband) filter. Here, for fun, is a New Horizons clear-filter image, which I've animated to show you what happens when you adjust the contrast -- you can reveal hidden plumes!

Volcanic plumes on Io
Volcanic plumes on Io As New Horizons approached the Jupiter system for its flyby, it captured many images of Io to search for active volcanic plumes. This animation is based upon two images captured on February 26, 2007, from a distance of about 4 million kilometers.Image: NASA / JHUAPL / SwRI / Animation by E. Lakdawalla

And here, because I can't not include it, is the famous New Horizons Tvashtar eruption sequence.

Tvashtar in motion
Tvashtar in motion In this amazing animation from the New Horizons flyby of Jupiter, the 300-kilometer-high plume erupting from Io's Tvashtar volcano is visibly in motion, its fountains of lava spraying up, out, and back down to the Ionian surface. New Horizons captured the motion fortuitously; the images were part of an observation of the ring system designed to search for structures in the rings, and because Io was close by the science team planned the ring images to encompass Io in the same frame. The animation contains five images taken over an eight-minute span of time beginning at 23:50 UT on March 1, 2007.Image: NASA / JHUAPL / SwRI

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