Jupiter Aurora

Solar Wind and Aurora at Jupiter


March 8, 2001

For higher resolution image, click here.

NASA's Earth-orbiting Hubble Space Telescope and Saturn-bound
Cassini spacecraft recently provided scientists an opportunity
to watch whether changes in Jupiter's glowing auroras
correspond in timing to fluctuations in the solar wind
reaching Jupiter.

While Cassini passed near Jupiter in December 2000 and January
2001, the Hubble telescope obtained ultraviolet images of the
ring-shaped aurora near Jupiter's north pole. The auroras,
comparable to Earth's northern lights, are glows caused when
charged particles steered by the planet's magnetic field
excite gases high in the atmosphere. They give an indication
of conditions in the invisible magnetic field. The Hubble
images were taken at times when instruments on Cassini were
measuring the solar wind approaching Jupiter. The solar wind
is a fluctuating stream of particles speeding away from the
Sun. The Cassini measurements allowed scientists to
extrapolate the properties of the solar wind even closer to
Jupiter, where it interacts with the planet's magnetic field.

One example of these sets of data is presented in this pair of
images. An image of Jupiter's northern aurora, taken by Hubble
on Dec. 16, 2000, shows the aurora as a white loop against a
blue background in the top frame. The bottom frame presents
information that Cassini's plasma spectrometer and
magnetometer instruments collected about the solar wind
reaching Jupiter at the same time. It gives measurements of
the solar wind's speed, density, pressure and magnetic-field
direction.

The Hubble Space Telescope is a project of international
cooperation between NASA and the European Space Agency (ESA).
It is managed for NASA by the Space Telescope Science
Institute, Baltimore, Md.

Cassini, on course to reach Saturn in 2004, is a cooperative
mission of NASA, ESA and the Italian Space Agency. The Jet
Propulsion Laboratory, a division of the California Institute
of Technology in Pasadena, manages Cassini for NASA's Office
of Space Science, Washington, D.C. More information about the
studies of Jupiter while Cassini passed it available online at:
http://www.jpl.nasa.gov/jupiterflyby .

Credit: NASA/JPL/University of Michigan