Many Astronomers, both professional and “backyard” alike claim M101 (AKA The Pinwheel Galaxy), as one of their favorite objects in the night sky. One defining feature is that from our vantage point, we are able to see M101 in a “top-down” view, which allows the wonderful spiral structure to be seen in its entirety. The above image, which utilizes data from multiple wavelengths shows the even distribution of both new and old stars in M101′s tightly-wound spiral arms. Composite views such as the image above allow astronomers to compare features visible in one portion of the spectrum tho those seen in others. Imagine being able to combine your normal vision with night-vision (infrared), AND Superman’s X-ray vision, all at the same time!

On a personal note, like many other astronomers, M101 is one of my favorite Messier objects. I’m not sure of the total integration time on the above image, however for comparison, here is an image from my 8″ telescope, with five minutes of total exposure time.

One (of several) reasons why the image from my own observatory isn’t as colorful as the NASA image shown above is that my image is only using visible wavelength data. Secondly, with my telescope only having a diameter of just over 200mm, the about of light captured by my telescope is a small fraction of what even the Hubble space telescope is capable of. Additionally, there are other factors such as the semi-rural location of my observatory which adds an element of light pollution to the mix, as well as interference from Earth’s atmosphere (all four telescope that provided data for the NASA image are space-based). Consider also, that while my DSLR might be 15.1 megapixels, the CCD present in the camera is designed for taking standard photos, and isn’t a “purpose-built” CCD specifically designed to collect data.

While not as detailed and colorful as the above image, consider the above image most likely uses data from the Hubble and Chandra space-based telescopes. Below is the wide-field raw image showing the location of M101 which is located in Ursa Major (Big Dipper). At a diameter of about 170,000 light-years, M101 is about 70 percent larger than our own Milky Way Galaxy, and is at a distance of roughly 21 million light years (6.4 Million Parsecs) from Earth.

Source:NASA Image of the Day / Serenity Valley Observatory