- Original Caption Released with Image:
-
This montage compares similar sides of Io photographed by the Galileo
spacecraft in October 1999 (left) and the New Horizons spacecraft on
February 27, 2007. The New Horizons image was taken with its Long Range
Reconnaissance Imager (LORRI) from a range of 2.7 million kilometers (1.7
million miles).
Most features on Io have changed little in the seven-plus years between
these images, despite continued intense volcanic activity. The largest
visible feature is the dark oval composed of deposits from the Pele
volcano, nearly 1,200 kilometers (750 miles) across its longest dimension.
At high northern latitudes, the volcano Dazhbog is prominent as a dark
spot in the New Horizons image, near the edge of the disk at the 11
o'clock position. This volcano is much less conspicuous in the Galileo
image. This darkening happened after this 1999 Galileo image but before
Galileo took its last images of Io in 2001.
A more recent change, discovered by New Horizons, can be seen in the
southern hemisphere (circled). A new volcanic eruption near 55 degrees
south, 290 degrees west has created a roughly circular deposit nearly 500
kilometers (300 miles) in diameter that was not seen by Galileo. Other New
Horizons images show that the plume that created this deposit is still
active.
The New Horizons image is centered at Io coordinates 8 degrees south, 269
degrees west.
- Image Credit:
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NASA/Johns Hopkins University Applied Physics Laboratory/Southwest
Research Institute
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