Saturday, August 7, 2010

Light phenomenas like the Northern Lights on Jupiter and other planets

Light phenomena like the Northern Light on Jupiter
Photo: John T. Clarke (U. Michigan), ESA, NASA

Did you know that light phenomenas like the Northern Lights (aurora borealis or aurora australis) can be seen on other planets? Unfortunately, Hurtigruten cannot take you there, but it's a fact that both Jupiter and Saturn have magnetic fields much stronger than Earth's, and both have large radiation belts. Aurora has been observed on both, most clearly with the Hubble Space Telescope. Uranus and Neptune have also been observed to have auroras.

The auroras on the gas giants seem, like Earth's, to be powered by the solar wind. In addition, however, Jupiter's moons, especially Io, are powerful sources of auroras on Jupiter. These arise from electric currents along field lines ("field aligned currents"), generated by a dynamo mechanism due to the relative motion between the rotating planet and the moving moon. Io, which has active volcanism and an ionosphere, is a particularly strong source, and its currents also generate radio emissions, studied since 1955. Auroras have also been observed on Io, Europa, and Ganymede themselves, e.g., using the Hubble Space Telescope. These are generated when Jupiter's magnetospheric plasma impact their very thin atmospheres.

Auroras have also been observed on Venus and Mars. Because Venus has no intrinsic (planetary) magnetic field, Venusian auroras appear as bright and diffuse patches of varying shape and intensity, sometimes distributed across the full planetary disc. Venusian auroras are produced by the impact of electrons originating from the solar wind and precipitating in the night-side atmosphere. An aurora was also detected on Mars, on August 14, 2004, by the SPICAM instrument aboard Mars Express.

Read more on Wikipedia

When travelling to Norway with Hurtigruten in the winter, you can experience the Northern Lights.

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