An Alarm Bell for Aurora

The World’s first auroral observatory was built by Kristian Birkeland in 1899 on the mountain Haldde just west of Alta in Northern Norway.

The observatory became permanently manned in 1912. One of the tasks of the observers was to take photographs of the aurora. This was done from two different locations at the same time in order to use the parallax to calculate the auroral altitude.

In a sense the early observers were space weather users. Rather than sitting outside waiting for the skies to clear and the aurora show up, they would use the fact that auroral currents would induce a signal in telegraph cables as the basis for an alert system warning about aurora!

I quote from the book “The Position in Space of the Aurora Polaris” by L. Vegard and O. A. Krogness:

At the telegraph station at Bossekop Mr. Feyling had kindly undertaken registering of earth-currents in two long telegraph lines by means of two miliampèremeters from RICHARD. The registering was produced mechanically, and for a certain deflection the diviating system closed a contact for an electric circuit which worked an electric bell. Now strong earth-currents are usually produced by the magnetic disturbances, and the latter in their turn generally accompanied by auroras. Thus by choosing a suitable deflection of the contact-maker we could use this signal as an indication of cosmic activity, and that aurora might be seen or might be expected soon to make its appearance. As the connection between aurora and magnetic disturbances is not a simple one, a strong aurora will not always follow such a signal; but still it will as a rule be the case, and the alarm bell has proved to be of considerable value to us and has saved much time.

The picture shows how the the observatory looks on a sunny Summer’s night. The buildings were refurbished during the 80s, and it is possible to lend the key at the local municipality for free. The observatory building itself can house up to 8 people sleeping over.