Watching a volcano leave the surface

Tvashtar above Io’s limb — NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
Processed image. A still from the five New Horizons LORRI views of 1 March 2007. Tvashtar’s upper plume rises about 330 kilometres above Io; its vent is beyond the limb and not visible. Open the recording to compare the discrete exposures. NASA published this product on 14 May 2007, separately from the observation date.
NASA/JPL image-use policy · credited mission observation, resized to WebP
· Original image source · Image licence

Compare volcanic plumes across spacecraft generations.

World: Io
Case date or period: Observations · 1997–2024

Look closer

Follow five actual camera exposures as Tvashtar’s plume changes above Io’s edge. Two minutes separate each view. Galileo’s older panels and Andrea Luck’s processed Juno photograph show other dates and volcanoes; compare their lighting and viewpoint before interpreting a difference as changing activity.

Follow the evidence

A plume’s outline changes with lighting and camera geometry. The older comparison also documents migrating source activity; it should not be read as a single uninterrupted film.

Built by people looking closely

The credited image processors worked with publicly available mission observations. Their versions are part of this collection, with each person’s processing and licence retained. Compare the treatments and return to the underlying source when a small detail matters.

A moving deposit is not a travelling volcano

The Galileo comparison records plume fallout at four dates between June 1997 and August 1999. One ring largely disappeared within eight months, while later deposits differed in size and their centres were roughly 125 kilometres apart. The mission team described this as apparent migration of active plume location. These transient surface deposits track changing activity; they do not show a mountain moving or one plume drifting continuously across Io. The panels also differ in illumination and resolution.

What a camera can miss

Ravine and colleagues’ 2025 JunoCam study found that even distant observations near Io’s day–night boundary could reveal plume tops lit by the Sun above dark ground. They also reported no directly observed Pele-type plumes, while noting that JunoCam lacks sensitivity to the shorter wavelengths commonly needed to see them. Fresh reddish deposits can supply separate evidence of activity. A missing visible plume therefore does not prove a volcano is inactive; spectral response and viewing geometry limit the comparison.