Astronomy Picture of the Day

While I am an incurable fan of looking at my own personal set of photons given off by deep sky objects, I can also be attracted to beautiful photographs of the same sky objects. I grew up with black and white versions of long photographic exposure time pictures that showed much more than I can see with my eye. These days, color photos and false color photos are all the rage. They are beautiful.

Sometime last fall, I decided to take an online course offered free by Robert Nemiroff (Michigan Technical University) from the upper peninsula of the state. It was an online collection of the lectures used for a college course. They were offered completely free as long as no college credit was needed. Dr Nemiroff is one of the editors of the Astronomy Picture of the Day (APOD). This is a NASA hosted site where one photograph or piece of art is featured each day. In the course, the students were responsible for knowing something about each one of the APODs for their testes.

I started taking a closer look at the descriptions under the pretty pictures. It turns out that the writing about the photographs is as well done as the photography. Here is a recent example:

“Why take a picture of just the Badlands when you can take one that also shows the spectacular sky above it? Just such a picture, actually a digital stitched panorama of four images, was taken in late June near midnight, looking southwest. In the foreground, the unusual buttes of the Badlands Wall, part of the Badlands National Park in South Dakota, USA, were momentarily illuminated by flashlight during a long duration exposure of the background night sky. The mountain-like buttes visible are composed of soft rock that show sharp erosion features from wind and water. The South Dakota Badlands also contain ancient beds rich with easy-to-find fossils. Some fossils are over 25 million years old and hold clues to the evolutionary origins of the horse and the saber-toothed tiger. Bright Jupiter dominates the sky on the left just above the buttes, while the spectacular Milky Way Galaxy runs down the image right.”

When I take a careful look at this prose, it is as illuminating as the photograph it described. Here is another recent description from the APOD site:

“Sprawling across hundreds of light-years, emission nebula IC 1396, visible on the upper right, mixes glowing cosmic gas and dark dust clouds. Stars are forming in this area, only about 3,000 light-years from Earth. This wide angle view also captures surrounding emission and absorption nebula. The red glow in IC 1396 and across the image is created by cosmic hydrogen gas recapturing electrons knocked away by energetic starlight. The dark dust clouds are dense groups of smoke-like particles common in the disks of spiral galaxies. Among the intriguing dark shapes within IC 1396, the winding Elephant's Trunk nebula lies just right of the nebula's center. IC 1396 lies in the high and far off constellation of Cepheus.”

I like the idea of the nebula sprawling across the heavens instead of many more prosaic ways of saying the same thing. I might have written something like “IC1396 I several hundred light years in diameter.”

I got into the habit of looking at the APOD each day while I was taking the course last fall. I keep a link to the APOD on my blog site. It is one of the great internet archives of both beautiful photographs and instructive descriptions of deep sky objects. There is a lot of cosmology to be learned just by reading the descriptions from a month’s worth of the APOD library. Enjoy them.

The daily APOD can be found at

http://apod.nasa.gov/apod/