Encyclopedia Entry #1 – Aurora

Welcome to the inaugural Encyclopedia Entry, where I will give you some brief, but interesting facts about various topics.  In this week’s entry, I talk about something that’s been in the news, and should be peaking in a few hours, aurora.

Aurora over Amundsen-Scott South Pole Station
Aurora over Amundsen-Scott South Pole Station

Aurorae are light emissions in the atmosphere caused by oxygen and nitrogen gaining an electron or going from an excited state to ground state.  These atoms are hit by energized particles from the sun that enter the atmosphere and are directed to the polar regions by the Earth’s magnetic field.

5 Interesting Facts

1.  Aurorae come in a variety of colours.  Usually they’re green, but they can also be red or blue.  Green aurorae are caused by oxygen atoms returning to ground state.  Red can also be caused by the same mechanism, but with a different energy level.  Blue is caused by nitrogen atoms regaining an electron after being ionized, while red is caused by nitrogen returning to ground state. For more, see here.

2.  Aurora borealis is visible in the northern hemisphere.  Aurora australis is visible in the southern hemisphere.

3.  Aurorae may cause sounds, but this is rare.  It has been observed by researchers. For more information, check this out.

4.  Aurorae are very strong and bright on Jupiter and Saturn, and have also been observed by telescope on Uranus and Neptune.  Venus and Mars also have aurorae, but are very diffuse due to the lack of a significant magnetic field.  Also, Io, Europa, and Ganymede have been observed to have aurorae. See here.

5. Aurorae are at their most frequent and strongest during the sun’s sunspot peak and the following 3 years.  The last peak was May 2013, so we are currently in an active period.

For more information, check out the Wikipedia article.

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