Ever stood outside looking at the aurora and felt as though it was swirling just a short distance above your head? It’s hard to judge altitude when looking at sky phenomena because there are few landmarks above us. (The moon effect at the horizon is an example.) But it turns out there is a way to measure aurora altitude.
The eerie, green glow of the Northern Lights swirls about in the video you see above. A group of researchers used a unique but simple technique to measure how high the electrons were during the dazzling light display: they mounted two digital SLRs eight kilometers (five miles) apart in Alaska, and used that old astronomical friend, parallax, to measure distances.
“Using the parallax of the left-eye and the right-eye images, we can calculate the distance to the aurora using a [triangulation] method that is similar to the way the human brain comprehends the distance to an object,” stated Ryuho Kataoka, an associate professor at the National Institute of Polar Research in Japan. “Parallax is the difference in the apparent position of an object when observed at different angles.”
Altitude measurements have been done before using this technique, but it’s the first time digital SLRs were employed, the research team said. A typical aurora has electrons that are between 90 kilometers and 400 kilometers (55 miles and 249 miles) high.
By the way, for all the amateur astronomy photographers, there’s a potential chance for you to get involved with future research activities.
“Commercially available GPS units for digital SLR cameras have become popular and relatively inexpensive, and it is easy and very useful for photographers to record the accurate time and position in photographic files,” said Kataoka. “I am thinking of developing a website with a submission system to collect many interesting photographs from night-sky photographers over the world via the Internet.”
Read the entire paper in Annales Geophysicae.
Source: European Geophysical Union