Jeff's Blog - Wednesday, August 31, 2016 - M31

Here's my second serious attempt at Astrophotography.

The Great Andromeda Galaxy, AKA Messier 31 or simply M31, photographed with my simple DSLR camera and my 70-300mm focal length zoom lens set to 262mm lens from beside the North Goodland Baptist Church in Imlay City, Michigan with the gracious permission of its pastor. This image was formed by combining seventy-three 20-second exposures, simulating a 24-minute exposure, along with many crazy shots which calibrated the source photos for the peculiarities of my camera and its sensor.

M31 is the nearest major galaxy to the Milky Way, at a distance of 'only' 2.5 million light years. Yes, the light in the glowing part of this image travelled for 2.5 million years, just to register its presence in my camera (and to my eyes, since M31 is barely visible to the naked eye from this dark sky site)! The glow of this majestic spiral galaxy is formed by bazilions of stars which are too distant and too close together to be resolved by this photo. The bright individual stars in the photo are foreground stars within the Milky Way galaxy in which we live. The dark swirly lines within the M31 galaxy are dust lanes which block our view of the bright glow behind them. They will someday condense and ignite into new stars which will harbor planets and perhaps people just like us.

The large fuzzy-spot above M31 is the galaxy M110, and the smaller round fuzzy spot to the lower-right of M31's core is the galaxy prosaicly named M32. Both M110 and M32 are dwarf elliptical galaxies in orbit around M31, our galaxy has similar subordinates named the Large- and Small Magellanic Clouds, visible from the southern hemisphere.

The bright star at the bottom of the frame is the naked-eye star named Nu Andromedae. North is to the upper left, east is to the lower left in the photo. The bright patch at the upper-right edge of M31 is NGC 206, a huge cluster of very bright class- O and B stars within M31. These massive superstars will live exceptional but short lives and explode as brilliant supernovae. Several of the globular clusters surrounding M31 are visible in the photo, but they look just like very faint stars so would be difficult for me to point out. As with most galaxies, at the center of the bright central glow of M31 is a black hole which is not visible to us, but dominates the destiny of stars and perhaps inquisitive explorers which venture too close to it.

To be clear, this photo (and all other astrophotos you'll see) does not represent what you can see if you look at M31 through a telescope. Instead, you'll only that fuzzy bright central glow, none of the outlying fainter glow. If you get good at observing and try hard with a larger scope (perhaps 10-inch aperture), you'll be able to see the faint glow along the top, separated from the bright glow by the dust lane, and you'll be able to see the large OB Association. When you look through a telescope, your eyes can only see the light immediately reaching them; they cannot integrate the light over a long period of time to build up a brighter image. The camera does just that, forming a brighter and therefore more detailed image that anything you could ever see through a telescope with your eyes. Of course, the sense of immediacy is lost; it's quite a thrill to look through a telescope and be seeing the light in real time with your very own eyes, and with only a couple lenses or mirrors making the view possible.

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