Stunningly Beautiful

Aurora Borealis

August 28, 1859: A great geomagnetic storm disrupts the night sky. On both this day, and on September 2, the Aurora Borealis was visible in more southern latitudes in the US, Europe, and Japan and a more northern latitude for the Aurora Australis in Australia. An aurora is a natural light display in high latitudes in both the Arctic and Antarctic regions. Solar wind colliding with the magnetosphere’s charged particles create a light show. This usually happens in a 3⁰ to 6⁰ wide latitude band and is usually at 10⁰ to 20⁰ from the geomagnetic poles. Although possible all year long, they are more vivid around the vernal and autumnal equinoxes. A geomagnetic storm can expand the auroral zones.

When a solar wind shock wave and/or cloud of magnetic field interacts with the Earth’s magnetic field, there is a geomagnetic storm. The increased solar wind compresses the magnetosphere and the magnetic field from the Sun interferes with the Earth’s magnetic field, transferring energy into the magnetosphere. Both of these events cause an increase in the movement of plasma through the magnetosphere as well as an increased electric current in both the magnetosphere and the ionosphere. The frequency of geomagnetic storms is directly related to the sunspot cycle on our local star.

Auroras or aurorae are classified as either diffuse or discrete. The diffuse pattern is, as the name suggests, diffused across the sky and may not be visible to the naked eye, even on the darkest night. Discrete auroras have sharply defined features and can vary to minimally visible to the naked eye to spectacular light shows. Even so, they are only visible in the night sky. Aurora comes from the Roman goddess of dawn, Aurora. Borealis comes from the Greek name for the north wind, Boreas. Australis or the southern lights, can be seen in Antarctica, South America, New Zealand, and of course, Australia.

The auroras that occurred on this day and on September 2 made quite a stir in the scientifically minded period in which they took place. Balfour Stewart presented a paper to the Royal Society on November 21, 1861 describing the events as documented by a self-recording magnetograph at the Kew Observatory. With this data, Stewart was able to establish a connection between the auroral event and the Carrington-Hodgson flare event the two men had observed. The flare was observed by the scientists, but people around the world noted the disruption in the auroras and the event was described in scientific literature to be sure, but also in ship logs and daily newspapers. Elias Loomis published a series of nine papers on the Great Auroral Exhibition of 1859 in the American Journal of Science in which he collected world-wide reports about the events.

Aurora had but newly chased the night, / And purpled o’er the sky with blushing light. – John Dryden

But when Aurora, daughter of the dawn, / With rosy lustre purpled o’er the lawn. – Homer

The sky grew darker, painted blue on blue, one stroke at a time, into deeper and deeper shades of night. – Haruki Murakami

Some praise the Lord for Light, / The living spark; / I thank God for the Night / The healing dark. – Robert W. Service

Also on this day: First Tornado Photograph – In 1884, the first tornado photograph is made.
Sci Am – In 1845, Scientific American began publication.
Odds and Evens – In 888, the last date written in all even numbers for over a thousand years.
Enceladus – In 1789, William Herschel found Enceladus in the night sky.