The Height of the Northern Lights: Using SLR Cameras to Measure the Aurora

The aurora borealis is one of the most spectacular sights on our planet. The green, purple and red waves that stretch across northern skies can be both beautiful and awe-inspiring as they light up snowy plains. Now, researchers have discovered a way to measure the height of the aurora, a technique that could let them learn a little bit more about these lights.

So how do you measure the Northern Lights? You use two digital single-lens reflex (SLR) cameras in order to capture 3D images of the Aurora. In fact, the new technique is based on the same way we see 3D images with our own eyes. The separation distance between the human eyes is what allows us to see in 3D. When we look at an object the images captured by the left and right eyes are slightly different from each other and when combined, give the brain the perception of depth. Since our eyes are so close together, though, this only works for objects that aren't very far away.

Because of this, it was important to put the two digital cameras far apart. In fact, the researchers placed the two cameras about 8 km apart across the Chatanika area in Alaska. Each of the cameras was equipped with fisheye lenses and GPS units.

"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," said Ryuho Kataoka from the National Institute of Polar Research in Tokyo, in a news release.

Altitude maps of the aurora are nothing new. But this is the first time that the emission height of the Northern Lights has been measured using images captured by two digital SLR cameras. This is a major discovery since it's far cheaper than other methods, which means that scientists can more easily and more frequently measure this altitude.

"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, in a news release. "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."

The findings could lead to a better understanding of the aurora and could further scientific research. In addition, the new technique could enable citizen scientists to contribute to this understanding.

The findings are published in the journal Annales Geophysicae.