The science of exploration through photography The Durango … – The Durango Herald

Greetings, stargazers.

In 1995 the Hubble science team released the image of the Pillars of Creation. This photograph fundamentally changed the way most of us think of astrophotography. Yes, the high resolution and image details were quite impressive, but it was the color palette that made this image unique. I have written individual columns about nebulae, astrophotography, astronomical filters, and a bit of spectroscopy, but these topics all come together to create these assigned color photographs.

The Pillars of Creation are part of the Eagle Nebula, which was discovered in the eighteenth century and is the 16th object on Charles Messiers list of fuzzy things that are not comets. It was first photographed in the late nineteenth century and had been a regular late twentieth century target for astronomers using film cameras. While the first images were black and white, color film can produce some really nice images that would match (at least somewhat) what we might be able to see with our naked eyes if they were sensitive enough.

Because the Hubble telescope was primarily a science mission, there was great interest in studying the composition of the universe by looking at specific wavelengths of light. Each element has its own unique spectral signature, or fingerprint, so looking for a certain wavelength of light associated with a specific element will reveal the distribution of that element. For example, excited hydrogen atoms emit a prominent red line at 656 nanometers, and taking a photograph through a filter that passes 656 nanometer light will show the distribution of hydrogen atoms.

Narrowband filters are made by building up multiple layers of dielectric coatings on a glass surface. These coatings are the same as the anti-reflective coatings you can get on your eyeglasses, but by using specific thicknesses and layers, selected wavelengths of light can be allowed to pass through, while others are reflected.

Instead of simply looking at one element at a time, it is possible to associate an element to one of the red, green, or blue portions of a 3-color photograph. In what is now called the Hubble Palette, a line of sulfur was assigned to be red, a line of hydrogen was assigned to be green, and a line of oxygen was assigned to be blue.

Narrowband filters are now readily available, although they are not cheap. As the quality of digital cameras has improved over the last couple of decades, so has the quality of Earth-based narrowband images. It is easy to recognize narrow band images because of the vivid colors, instead of the overall magenta tones from hydrogen gas seen in natural light.

As the use of the Fort Lewis observatories continue expanding, I hope that more of these narrowband images will be produced locally.

Hubble image updates

https://hubblesite.org/contents/news-releases/2015/news-2015-01.html

Astronomy picture of the day

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

An Astronomers forecast for Durango

http://www.cleardarksky.com/c/DrngoCOkey.html?1

Old Fort Lewis Observatory

http://www.fortlewis.edu/observatory

hakes_c@fortlewis.edu

This month

Charles Hakes teaches in the physics and engineering department at Fort Lewis College and is the director of the Fort Lewis Observatory.

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The science of exploration through photography The Durango ... - The Durango Herald