Aurora (astronomy)

:For other meanings, see Aurora

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In astronomy, an aurora is an optical phenomenon characterised by colourful displays of light in the night sky, caused by the interaction of charged particles from the solar wind with the upper atmosphere of a planet. The most powerful aurorae tend to occur after coronal mass ejections.

Related Topics:
Astronomy - Optical phenomenon - Light - Night - Sky - Solar wind - Planet - Coronal mass ejection

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On Earth, Jupiter, Saturn, Uranus and Neptune, aurorae are caused by the interaction of solar wind particles with the planet's magnetic field, and are therefore most prominent in higher latitudes near the magnetic poles. For this reason, the aurora occurring in Earth's Northern Hemisphere is called the aurora borealis, or northern lights; and in the Southern Hemisphere the aurora australis. However, aurorae also occur on Venus and Mars, which lack planetary magnetic fields. On Venus, atmospheric molecules are energised directly by the solar wind; on Mars, aurorae occur near localised magnetic anomalies in the planetary crust which are remnants of a presumed former planetary magnetic field which is now long extinct.

Related Topics:
Earth - Jupiter - Saturn - Uranus - Neptune - Magnetic pole - Northern Hemisphere - Southern Hemisphere - Venus - Mars - Crust

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On Earth, aurorae occur when the Van Allen radiation belts become "overloaded" with energetic particles, which then cascade down magnetic field lines and collide with Earth's upper atmosphere.

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In Latin, aurora means "dawn".

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