Volcanic Moon Creates Glowing Aurora Spots on Jupiter

[n2doc]

An ultraviolet image taken by the Hubble Space Telescope (top) shows glowing auroral structures around Jupiter's north pole. A bright spot near the center of the image is known as the Io footprint, because researchers think it is created by interactions between Jupiter and the volcanic moon Io.

Now astronomers have described a new model for these interactions in which the moon disrupts the flow of particles in a donut-shaped cloud (yellow) around Jupiter, as seen in an artist's conception (bottom). This sends plasma waves (blue) curving around the moon from one pole of Jupiter to the other that generate electron beams (red) along the planet's magnetic field lines.

Images courtesy LPAP/Université de Liège

Anne Minard
for National Geographic News
March 20, 2008
Unexpected spots on Jupiter's poles could solve the decades-old mystery of what powers the gas giant's spectacular "hyper-auroras," according to a new study.

Auroras were first spotted on Jupiter in 1979, and astronomers have known since the 1990s that the planet's polar light shows are hundreds of times more powerful than Earth's auroras—with bands and curtains that can get as big as Earth itself.

Scientists think that Jupiter and its fiery moon Io are working in concert to cause these seemingly nonstop auroras.

The volcanic moon creates what's known as the Io footprint: a bright spot followed by smaller spots that are downstream of the flow of charged particles around Jupiter.

more:

http://news.nationalgeographic.com/news/2008/03/080320-jupiter-auroras.html

[Mika]

1. Great animation here

10mb

http://chandra.harvard.edu/photo/2007/jupiter/jupiter_aurora_lg.mov

[Jack Rabbit]

3. Cool

Thanks.

[Mika]

2. Galileo photo and analysis of Jupiter's northern aurora

PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE [phone]
http://www.jpl.nasa.gov

PHOTO CAPTION P-48699
June 5, 1997
False Color Aurora

Data from NASA's Galileo spacecraft were used to produce this
false-color composite of Jupiter's northern aurora on the night
side of the planet. The height of the aurora, the thickness of
the auroral arc, and the small-scale structure are revealed for
the first time. Images in Galileo's red, green, and clear filters
are displayed in red, green, and blue respectively. The smallest
resolved features are tens of kilometers in size, which is a ten-
fold improvement over Hubble Space Telescope images and a
hundred-fold improvement over ground-based images.

The glow is caused by electrically charged particles impinging on
the atmosphere from above. The particles travel along Jupiter's
magnetic field lines, which are nearly vertical at this latitude.
The auroral arc marks the boundary between the "closed" field
lines that are attached to the planet at both ends and the "open"
field lines that extend out into interplanetary space. At the
boundary the particles have been accelerated over the greatest
distances, and the glow is especially intense.

The latitude-longitude lines refer to altitudes where the
pressure is 1 bar. The image shows that the auroral emissions
originate about 500 kilometers (about 310 miles) above this
surface. The colored background is light scattered from Jupiter's
bright crescent, which is out of view to the right. North is at
the top. The images are centered at 57 degrees north and 184
degrees west and were taken on April 2, 1997 at a range of 1.7
million kilometers (1.05 million miles) by Galileo's Solid State
Imaging (SSI) system.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission
for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are
posted on the World Wide Web, on the Galileo mission home page at
URL http://www.jpl.nasa.gov/galileo. Background information and
educational context for the images can be found at URL
http://www.jpl.nasa.gov/galileo/sepo