CMU physics professor traveled to both hemispheres to complete all-sky panorama

Axel Mellinger has a hobby that takes him halfway around the world.

The assistant physics professor is an amateur photographer and finished his second all-sky panorama in August. The photo, which took 22 months and two trips to South Africa, shows the entire night sky and allows viewers to see connections between night sky elements.

“It’s only my hobby,” he said. “During the daytime, I do polymer physics.”

In order to complete his all-sky image, Mellinger needed to photograph from the northern and southern hemispheres. He traveled to Texas and northern Michigan to take the photos for the northern hemisphere.

“What’s unique about Dr. Mellinger’s work is that it stretches and you can see how everything fits together,” said David Batch, director of Abrams Planetarium in East Lansing.

Comprehensive photo

Most astronomy photographs are of a very specific part of the sky, Batch said. Mellinger’s work allow viewers to see how objects are related.

Another unique part of Mellinger’s work is the color and exposure. He took each photo with red, green and blue filters, and used three exposure times in order to have proper dynamics. For clarity, he repeated the entire process five times to average the effects.

“I divided the sky in a grid of 70 fields, starting at the North Celestial Pole,” Mellinger said. “It takes about an hour and 40 minutes to complete each field.”

The photos show lanes of dust and any organic, metallic or silicate microscopic material, across the sky, said physics professor Glen Williams. It obscures light and causes distant stars to have a red tint.

“I was stunned when I saw his picture, and you see these dust lanes more clearly than I’ve ever seen before,” he said.

Serious hobby

Photography has been a serious hobby of Mellinger’s since he was a child. In 1998, he put together images of the Milky Way, which his friends said resembled a painting of the sky. Mellinger finished his first full-sky panorama in the late 1990s with a chemical film camera to replicate the painting. As a physicist, he had the skills to do the image processing.

“It was something that not a lot of other people were doing,” Mellinger said.

The new panorama was taken by a digital camera, offering instant feedback and allowing Mellinger to avoid photographing airplanes.

It’s actually quite a big problem if you do wide field astrophotography, he said.

Mellinger hopes his image will be placed in planetariums world-wide, and Williams agrees with its potential as an educational tool.

“It shows students and even professors in a very clear way what the galaxy looks like,” Williams said.