Date: July 22, 2011
Title: Auroras and the Solar Storm of 1859
Podcaster: Liminality
Organization: Binary Particle
Links: If you want to be part of a science database or just read about some interesting components of science, visit: http://www.binaryparticle.com/.
Description: The aurora is a fascinating and beautiful phenomenon that has captivated the minds of many people through history, we’ll take a look at some details about aurorae and the greatest solar storm ever recorded in history.
Bio: Liminality is the creator of Binary Particle, and a science fan.
Sponsor: This episode of 365 Days of Astronomy is sponsored by — no one. We still need sponsors for many days in 2010, so please consider sponsoring a day or two. Just click on the “Donate” button on the lower left side of this webpage, or contact us at signup@365daysofastronomy.org.
Transcript:
Hello, I’m Liminality from binaryparticle.com, today I’m going to talk to you about auroras and what causes them.
First, let’s start with some history.
On August 28, 1859 an unexpected solar storm reached the Earth, causing electromagnetic disturbances that were specially noticeable in the electrical telegraphs of the time, when seemingly most of them were unusable for no apparent reason, it also caused spectacular auroras all around our planet, the known sightings go as far south as the Caribbean; it ended on August 30 and it could have been the greatest solar storm on record, but just a couple days later, on September 1st when everything seemed to be going back to normal, English amateur astronomers Richard Carrington and Richard Hodgson independently witnessed the first and possibly largest solar flare that has been observed by astronomers, which was later called the Carrington Super Flare.
This super flare announced what was soon to come, it was probably related to a coronal mass ejection that released a massive number of charged particles that quickly reached the Earth, taking about 18 hours, when it usually takes days for particles coming from the Sun to get to our planet. The Earth’s magnetic field was completely overwhelmed by the storm, auroras were seen near the Equator and again, most of the telegraphs were unusable, but there are records of people that were under the right circumstances to produce geomagnetically induced currents that allowed them to use their telegraphs even when disconnected from their power supplies.
After a few days, the second storm finally ended, we now refer to it as the Carrington event, if a solar storm of that scale were to happen in modern times, it could cause serious damage to the whole electrical system of entire cities.
Now, let’s talk about the relationship between the solar wind and auroras. The Sun is constantly releasing matter into space, forming what we know as the solar wind, and the Earth’s magnetic field usually protects us from most of the charged particles released by the Sun, but sometimes a solar flare or a coronal mass ejection happens to be pointing at us and the number of charged particles that the Earth receives can be much larger than usual, causing a geomagnetic storm. Guided by the magnetic field, the charged particles reach the gases of the Earth’s atmosphere, when they collide with oxygen and nitrogen, the energy puts the oxygen atoms in an excited state, so when they return to their ground state they emit green or red light, while ionized nitrogen emits blue light when it regains an electron; that is what we know as aurora.
Some auroras can be regularly seen near the polar regions, but the really intense ones appear due to coronal mass ejections. Some of the best places to look at auroras are Canada or Alaska, specially during a period of solar maximum and keeping an eye on the space weather to know what to expect.
Even though auroras are commonly associated with the north pole and are usually called northern lights, the same phenomenon also occurs in the south pole, know as aurora australis
Is not surprising that the cultures lucky enough to have witnesed such a beatiful phenomenon have tried to explain it in their own way, the name aurora borealis comes from the Roman goddes of dawn, Aurora and the Greek god of the north wind, Boreas; it has appeared in drawings and folklore since pre-historic times, seen as spirits or signals from gods.
If you want to help a science database grow or just read some interesting things about science, visit binaryparticle.com
Thanks for listening
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365 Days of Astronomy
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