Snapshots of the Universe

Taking pictures is relatively easy nowadays. Anyone can whip out a smart phone from their pockets and snap a still image of what they're looking at in seconds flat. It's simple.

However, the same can not be said for photographing celestial objects. Simply pointing a telescope at an object in the sky and taking a picture through the eyepiece doesn't yield the colorful landscapes we all know and love. Following this method for astrophotography wouldn't yield very exciting results results.

M17: Swan Nebula - visual light only

This is because we rarely use optical light alone to image objects in the sky. Instead, we filter the light through different wavelengths, take long-exposure images with each filter, and combine the images to form a photograph that truly characterizes the object. This is how professional astrophotography works. 

M17: Swan Nebula - all wavelengths of light

In lab for my astronomy class at school, we went up to SUNY Oneonta's observatory and imaged objects of our choice. This was to help us learn about CCD cameras, the process of astronomical imaging, and how it isn't as simple as the "point and shoot" method. 

The object I chose to image was Neptune, the eighth and furthest planet in our Solar System. I can never get enough of planets. The fact that there are other worlds besides our home planet will always be one of my favorite things about this Universe. The reason I chose Neptune over other planets is pretty simple: There weren't any other planets above my local horizon at the time. Well... That's not entirely true. Uranus was visible at the time, but I never really liked Uranus, so I went with Neptune! 

One of the first steps in astrophotography is taking what is called a "bias frame" 

Bias Frame

Bias frames are just images of the natural static of the camera. We take images of this so that we can subtract this static from the images we take of our desired object. This enables us to have as clear of an image as possible. 

Following this, I pointed the 16-inch Schmidt-Cassegrain telescope to Neptune. With an exposure of roughly ten seconds, I took a series of photographs with various filters. 

Neptune - Red Filter

Neptune - Green Filter

Neptune - Blue Filter

Alone, these photographs don't look like much. It's even hard to distinguish which of these bright dots is Neptune. However, with manipulation and layering via photoshop (something I have yet to learn about), a final image can be created. This is the image my astronomy professor created with my filter images:

As you can see, the blue color of Neptune (the bottom object) is really apparent now that all the images have been combined. I am satisfied with the results, even though the planet just looks like a tiny blue speck. Neptune is far away and incredibly small in astronomical terms, so an image of this quality from an undergraduate astronomy student is very gratifying.