- Original Caption Released with Image:
-
This image of Io eclipsed by Jupiter's shadow is a combination of several
images taken by the New Horizons Long Range Reconnaissance Imager (LORRI)
between 09:35 and 09:41 Universal Time on February 27, 2007, about 28
hours after the spacecraft's closest approach to Jupiter. North is at the
top of the image.
In the darkness, only glowing hot lava, auroral displays in Io's tenuous
atmosphere and the moon's volcanic plumes are visible. The brightest
points of light in the image are the glow of incandescent lava at several
active volcanoes. The three brightest volcanoes south of the equator are,
from left to right, Pele, Reiden and Marduk. North of the equator, near
the disk center, a previously unknown volcano near 22 degrees north, 233
degrees west glows brightly. (The dark streak to its right is an
artifact.)
The edge of Io's disk is outlined by the auroral glow produced as intense
radiation from Jupiter's magnetosphere bombards the atmosphere. The glow
is patchy because the atmosphere itself is patchy, being denser over
active volcanoes. At the 1 o'clock position the giant glowing plume from
the Tvashtar volcano rises 330 kilometers (200 miles) above the edge of
the disk, and several smaller plumes are also visible as diffuse glows
scattered across the disk. Bright glows at the edge of Io on the left and
right sides of the disk mark regions where electrical currents connect Io
to Jupiter's magnetosphere.
New Horizons was 2.8 million kilometers (1.7 million miles) from Io when
this picture was taken, and the image is centered at Io coordinates 2
degrees south, 238 degrees west. The image has been heavily processed to
remove scattered light from Jupiter, but some artifacts remain, including
a horizontal seam where two sets of frames were pieced together. Total
exposure time for this image was 56 seconds.
- Image Credit:
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NASA/Johns Hopkins University Applied Physics Laboratory/Southwest
Research Institute
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