|AAPT Winter Meeting 2006|
The aurorae come in two forms. The analogue form has an orange-red colour, and is produced by the D-state in oxygen. The discrete form has a green colour, and is produced by the S-state in oxygen. One often sees purple from ionized nitrogen. There are also sounds linked to the aurorae.
Heliophysics is a study linking geophysics to astrophysics at heliophysical windows to Earth. 2007 is the International Heliophysical Year.
The aurorae are powered by solar electrons and protons carried by the solar wind. The planetary magnetic field modulates and redirects the particles. Planet-wide, the aurorae dissipate 1000 GW, compared to 500 GW total electrical generation in the USA.
Solar flares cause a re-alignment of the planetary magnetic field, resulting in the aurorae. They oin the north and south "windows" in the field. Aurorae occur on other planets with magnetic fields, such as Jupiter and Saturn. Aurorae can be used to detect extra-solar planets, and whether those planets harbour life.