Figure 1: Andromeda Galaxy, imaged in October 2022 at Lac Teeples.
The Andromeda Galaxy, also known as Messier 31, M31, or NGC 224 and originally the Andromeda Nebula, is the nearest large galaxy to our home, the Milky Way. It is a huge object in our sky, much greater in apparent size than the moon. A giant spiral galaxy similar to the Milky Way it is probably the most often studied object outside our own Milky Way.
It’s big, it’s nearby and it’s spectacular.
It’s big, as in having 1000 billion, or one trillion, stars (perhaps three times as many as the Milky Way), and big in extending over 3 degrees by 1 degree on the sky. Nearby is perhaps debatable, at 2.5 million light-years away, although that makes it part of our local group of galaxies. Spectacular… well that’s in the eye of the beholder.
I wondered which part of the galaxy is closest to us and researched this question. As it is presented here, our perception would suggest that the bottom part is closest. I think this is because we tend to look down from above on objects like this in real life. I could rotate the image and reverse that perception. Apparently it isn't entirely settled, but the top part as shown here is believed to be the closest, and the bottom is most distant.
The Andromeda Galaxy is the most distant object I’ve ever seen with the naked eye and that was only once, from Bon Echo Provincial Park. They say it can be seen quite easily, but even from Lac Teeple dark skies I need binoculars. With binoculars I can find it very quickly and easily: It has the appearance of a small starry cloud, although I can’t make out any actual points of light.
In 964 the Persian astronomer Abd al-Rahman al-Sufi first documented Andromeda, although it had been seen long before this date. He called it the “little cloud”, which makes sense to me. That name, “little cloud”, began to be used in star catalogues. Telescopes were invented in the early 1600s, so al-Sufi did not have one in hand.
There was some early speculation that Andromeda was an island universe, outside the Milky Way galaxy (1745), and Messier catalogued it as Messier #31 in the 1760s. Twenty years later William Herschel observed some structure and a reddish core. Herschel estimated the distance to be around 20,000 light-years: The true distance is 100 times greater.
In 1850 the Earl of Rosse, using the Leviathan telescope, drew a picture of the Andromeda Nebula that showed the spiral structure. In 1864 it was realized that the light spectrum of the galaxy was a continuum of frequencies, like what we’d expect from a star, unlike the spectral line structure of other nebulae.
Figure 2: This image (Wikipedia; Andromeda Galaxy, in the public domain) is an early astrophotography photo taken in 1899 by Isaac Roberts.
The Andromeda Galaxy is easily observed from the northern hemisphere, it is nearby and of great apparent size, showing clear spiral arms, dust lanes, star formation regions, basically everything we would expect to find in a spiral galaxy. Discoveries of supernovae in this galaxy, outside the Milky Way, contributed significantly to the realization that these types of “nebulae” were in fact island universes, galaxies. Decades of work in this area culminated with the work of Mr. Hubble who settled the question of island universes.
Oddly, given all the information above, I have had trouble creating a good image of this galaxy. It is big enough that one needs a wide-field telescope, but my current system is almost perfect for this. The galaxy is very bright, so I was getting nice images in one or two minutes, but I did struggle to get decent colour: Early attempts were basically black & white. Finally, the background has a certain level of glow, which is real, but processing tended to create wavy light patterns in the dark sky.
The image here, part of my “new series” using additional narrowband imaging, seems to have largely resolved all previous problems. The core is quite large, and I’d prefer it be smaller (did I saturate a big region?), but this bright core seems to contribute to a sense of the power and majesty of the target. It works. The colour is strong and the red star-formation nebulae are very apparent due to the Hydrogen-alpha narrowband imaging. Spectacular? Yes, it is.
The Andromeda Galaxy image at top was created by RGB data supplemented by Hydrogen-alpha narrowband data. Imaging began in August 2022 and was completed in October 2022. Each channel has approximately 1 hour of data, with 3 hours of Hydrogen-alpha narrowband for a total of around 6 hours. RASA-11, ZWO ASI6200MM camera. Lac Teeples Deep Sky Observatory.
Something like this puts the modesty of our own very small lives in perspective.
It is little wonder that people instinctively look to the existence of a higher force ie. God.