December 16, 2004
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