Jupiter has a very large and very complex magnetic field.
More Info: While Jupiter has only a small rock and metal core about the size of the Earth, the core is surrounded by an extensive layer of liquid hydrogen with metallic properties such as conductivity. Combined with Jupiter’s fast rate of rotation at only about 10 hours per cycle, the liquid hydrogen produces a very strong magnetic field, which is about 20,000 times stronger than Earth’s magnetic field. * [“Jupiter and Saturn” University of Northern Iowa]
The enormous magnetosphere of Jupiter has a diameter of 30 million kilometers, which is even larger than the sun. The large magnetosphere interacts with the charged particles that make up solar wind. The solar wind pushes the magnetosphere into an elongated shape that extends beyond the orbit of Saturn. [“Jupiter’s Magnetic Field.” Georgia State University]
Aurorae of Jupiter
The magnetic field of Jupiter can be observed by the strong aurorae usually visible at its poles. Ions in the atmosphere follow the magnetic field lines down to the pole where they interact with atmospheric particles to produce light. The aurorae of Jupiter are some of the most active in the solar system because the atmosphere of Jupiter receives a flux of ions from Ios, its volcanically active moon, greatly increasing the frequency and intensity of aurorae. [“A Close Up of Aurora on Jupiter.” NASA]
*Some sources place this number at more than 20,000 times that of Earth. [“The Outer Planets: Giant Planets: Magnetospheres” Colorado State University]
“Jupiter and Saturn.” University of Northern Iowa | University of Northern Iowa. N.p., n.d. Web. 13 Dec. 2012. http://www.uni.edu/morgans/astro/course/Notes/section4/new20.html
“Jupiter’s Magnetic Field.” Georgia State University. N.p., n.d. Web. 6 Jan. 2013. <hyperphysics.phy-astr.gsu.edu/hbase/solar/jupmag.html>.
“A Close Up of Aurora on Jupiter.” NASA Astronomy Picture of the Day. N.p., n.d. Web. 6 Jan. 2013. http://apod.nasa.gov/apod/ap001219.html
“The Outer Planets: Giant Planets: Magnetospheres.” Laboratory for Atmospheric and Space Physics Colorado State University. N.p., n.d. Web. 6 Jan. 2013. http://lasp.colorado.edu/education/outerplanets/giantplanets_magnetospheres.php