Jean-Luc Dauvergne from France reports the possible detection of a volcanic plume on Io attached to the Loki Patera region. The detection occurred on a series of images and videos obtained on 29 July 2021 at around 23:40 UT with a 300 mm telescope. Moisés Portillo from Spain reports a similar event from a set of images obtained on 28 July at around 01:49 UT (see image on the right). This is probably the first detection of a volcanic plume on Io from ground-based telescopes (ground-based observations of Io with large telescopes monitor the volcanic activity through the detection of hot spots in the surface without resolving volcanic plumes). Frank Marchis, an specialist on high-resolution imaging of Io reports that Io has been active since the month of April.
We encourage observers to look for possible additional detections of this plume in images of Io obtained close to 29 July and in recent observations. Volcanic plumes are better detected on the blue channel than in red light because the light observed is diffused in the tenuous material of the plume. So, color observations that do not show the plume might be checked in its blue channel.
See Jean-Luc's images and his report on Astrosurf.