Volcano of the Month

 

The first images returned to Earth by New Horizons during its close encounter with Jupiter feature the Galilean moon Io, snapped with the Long Range Reconnaissance Imager (LORRI) at 0840 UTC on February 26, while the moon was 2.5 million miles (4 million kilometers) from the spacecraft. This is the clearest view yet of a plume from Tvashtar, one of Io's most active volcanoes. Ground-based telescopes and the Galileo Jupiter orbiter first spotted volcanic heat radiation from Tvashtar in November 1999, and the Cassini spacecraft saw a large plume when it flew past Jupiter in December 2000. The Keck telescope in Hawaii picked up renewed heat radiation from Tvashtar in spring 2006, and just two weeks ago the Hubble Space Telescope saw the Tvashtar plume in ultraviolet images designed to support the New Horizons flyby.

 

 

The New Horizons images of the plume ? which show features as small as 20 kilometers (12 miles), are 12 times sharper than the Hubble images and about three times sharper than the Cassini images. "This is the best image of a large volcanic plume on Io since the Voyager flybys in 1979," says John Spencer, deputy leader of the New Horizons Jupiter Encounter Science Team from Southwest Research Institute. "If the Tvashtar plume remains active, the images we take later in the encounter should be even better.