Northern Lights' Height Can Be Determined Using Just Two Digital Cameras, Say Researchers [VIDEO]
Using two cameras placed five miles apart, Japanese researchers were able to measure the altitude of aurora borealis, or the Northern Lights, according to a study published in the geoscience journal Annales Geophysicae.
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The scientists were able to determine the height of the Northern Lights by placing two digital single-lens reflex (SLR) cameras in the Chatanika area of Alaska. The two digital SLR cameras used fisheye lenses and GPS to capture images of the sky at the same time, and combined them to make a 3D image (video below).
"We had initial success when we projected the digital SLR images at a planetarium and showed that the aurora could be seen in 3D. It was very beautiful, and I became confident that it should be possible to calculate the emission altitude using these images," said lead paper author Ryuho Kataoka, from the National Institute of Polar Research in Tokyo, Japan.
In humans, objects appear in 3D because of the slight difference between how an object is seen from the right eye versus how it's seen from the left. Because the eyes are only set a few inches apart, only close objects are glimpsed in 3D. For very far away objects, like the Northern Lights, the distance between the two "eyes" -- in this case, the two cameras -- had to be very great in order to form a 3D image.
"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," Kataoka said.
While the Northern Lights' altitude has been determined before, the researchers say that the two-camera method is a low cost and effective way for professional and amateur astronomers to measure objects in the sky. Kataoka said he's considering starting a website for photographers to share night-sky images.
"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.
The Northern Lights appear when electrically charged solar particles enter the atmosphere and collide with Earth's gaseous particles. The Northern Lights' colors change depend on the different types of gas involved in the collision. The Northern Lights' altitudes range from about 50 to 250 miles; different altitudes have different gases, and hence create auroras of different colors. Yellow-green, the most common Northern Lights color, is caused by oxygen molecules 60 miles about the Earth.
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