The year was 1892. While most of the world was still celebrating the dawn of a new year, two German gentlemen had other ideas. For on January 1, 1892, astronomer and physicist Martin Brendel along with geographer and meteorologist Otto Baschin reached a crucial phase of their mission.
Brendel braves the cold
Having set out to study the Northern lights (aurora borealis) and conduct magnetic field measurements, Brendel and Baschin arrived at Altafjord in northern Norway on January 1. Having reached a latitude just shy of 70° N, they went about their next steps. On January 5, Brendel managed the first successful auroral photograph that survives to this day.
Even though the photograph turned out to be blurred and had low contrast, the black-and-white image went some way towards conveying the shape of the observed aurora. In order to study the science of aurora, Brendel spent two months during the coldest and darkest part of the year living in the Arctic Circle. One of his photographs, taken on February 1, 1892, went on to be published in a magazine, giving many people their first glimpse of this eye-catching phenomenon.
What causes these?
The reason behind auroras remained a mystery for long. We now know that auroras are a result of an interaction between energetic particles from the sun and the earth’s magnetosphere – the region in the earth’s atmosphere and beyond where the effects of its magnetic field can be felt.
De-excite, it is!
Energetic particles can speed out from the sun either as a steady stream called the solar wind or as a result of massive eruptions known as coronal mass ejections. When these charged solar particles reach the earth, they react with the magnetic fields.
As a result of this reaction, the atoms in the region get excited, meaning they move to higher-energy orbits, away from the nucleus. When they de-excite, that is, fall back from the excited energy level to a lower energy level, a photon of light is released. The vastness in scale leads to the aurora.
While the Northern lights or aurora borealis in the northern hemisphere is more popular, it has a counterpart in the southern hemisphere called the Southern lights or aurora australis. Even though aurora australis is equally brilliant, it isn’t often mentioned in the same breath as aurora borealis only because there isn’t enough accessible landmass for us to observe it. The regions bordering the Arctic Ocean afford better spots to observe this phenomenon than in the Antarctic, which remains largely inaccessible.
The camera eye
The first colour photographs of aurora were only taken in the middle of the 20th century and in the decades that have followed, they have given us some of the best shots of our night sky. It is interesting to note that the eye of the camera in fact does a better job at capturing these dancing lights, when compared to our own eyes.
This is because the human eye perceives the aurora in the night only in faint colours and in shades of gray and white. As the cameras carry no such restrictions and have the added ability of longer exposure times, among other capabilities, they are able to reproduce the colours and magnificence of the aurora, thus giving us a better picture of it as it appears in the sky.
The auroras are no longer the mysteries they used to be, but it hasn’t stopped fascinating viewers, holding them spellbound. Even if not to witness the science in action, it surely is worth a visit, to see the kind of thoughts and imagination that such a sight stirs inside you.
