It seems I catch a glimpse of M31 with my unaided eye about once a year. The night of October 19-20, 2009, was one of the best I have seen in Maryland for a long time for astrophotography or visual observing. M31, which is located about 2.5 million light years from Earth, is said to be the most distant object that is visible to the unaided eye. I was able to see it from my driveway on the night of October 19-20, 2009 with dark-adapted eyes. It only made sense to try to make my first photo of M31. M31 is an image-processing challenge because the extreme contrast between its bright core and the dimmer regions and dust lanes.

Among the public, persons who know what a galaxy is are likely to think of the spiral galaxy M31 as the paradigm of a galaxy. There is no such paradigm, as galaxies come in every conceivable size and shape, and in no shape at all (amorphous). M31 must, however, look very much like our home galaxy, the Milky Way, would look if viewed from a suitable distance.

Speaking of distance, M31 is a little bit closer to you now than it was when you started reading this. The Milky Way and M31 are moving toward each other with a net velocity of about 120 km/sec. They will meet in about 2.5 billion years. It will not be a violent collision for the most part—the distance between stars within the two galaxies is very great (except at the cores, where tightly packed stars orbit the massive central black holes) and stars will not be colliding and merging or being smashed to bits. While there are too many unknown variables to predict the outcome of the collision, one possibility is the creation of a single, giant elliptical galaxy. The fate of the massive central black holes is impossible to predict. What would happen to the Sun and planets? Again, the answer is unknown, but the possibilities range from not very much at all to ejection from the galaxy by gravitational forces. The human race will either have moved elsewhere or become extinct by then, so chances are the fate of the Solar System will matter only to the bacteria that survive deep underground as the Sun ages and moves toward its red-giant phase.

Notice M31's much smaller companion galaxies, the dwarf elliptical galaxies M110 (top left) and M32 (center right). M31 is believed to have at least 14 dwarf galaxies gravitationally bound to it. There are numerous named objects and areas in the vicinity of M31. The blue star cloud at top right is called NGC 206. The Milky Way also has a number of companion galaxies, the most prominent of which are the Greater Magellanic Cloud and the Lesser Magellanic Cloud, which are visible from the southern hemisphere.

M31 is believed to contain about one trillion (10¹²) stars, compared to between 200 and 400 billion (4X10¹¹) in the Milky Way. Recent measurements of dark matter, however, show evidence that the Milky Way is as massive as M31 and possibly slightly more massive.

This image is all Mac: Equinox 6, PHD Guider, and Nebulosity controlled the Astro-Physics 1200GTO mount and Takahashi 6-inch refractor, the Starfish guide camera, the RoboFocusers, and the SBIG STL-11000M CCD camera. Images were reduced with Nebulosity, Pixinsight, and Photoshop. Everything ran on 15" and 17" MacBook Pro's.

Attention sentient beings everywhere! If your planetary authorities should alert you that your home star is about to “go supernova” in the near term, drop what you are doing and proceed immediately to the designated assembly point for your planetary evacuation ship. The filaments of gas seen in this inverted (photographic negative) Hydrogen Alpha (Hα) image are the remnants of a star that exploded about 43,000 years ago. The only parts of the star that remain are the gas that you see in this image and a neutron star, or pulsar. If the stellar core had been more massive it would have collapsed into a black hole. Click here for a larger version.

Planets have been discovered orbiting neutron stars, but it is not known whether they survived the supernova explosion or formed afterward. It would seem that a planet orbiting a massive star that exploded as a supernova should be thrown out of its orbit and ejected into interstellar space because the gravitational dynamics of the star system would change radically and suddenly; specifically, the star’s gravitational pull on the planet would suddenly weaken. In any case, it is unlikely that any planets that might have orbited the doomed star contained advanced life, because the massive stars that undergo supernova explosions have life spans that are too short for intelligence to evolve on their planets. The Earth is about 4.5 billion years old and it required practically all of that time for self-aware primates (that's you and me) to evolve; we have been here for a mere blink of an eye compared to the age of the Earth. Massive stars that are bound to end up as supernovas have life spans that are measured in just a few millions of years—perhaps 10 to 20 million. Since we don't know of any life elsewhere, we have no basis for a firm statement, but it seems extremely unlikely that a planet just 10s of millions of years old could evolve intelligence. A planet that formed in orbit around the neutron star after the explosion would be subjected to extremely high levels of X-ray and Gamma radiation that would be inimical to the origin and evolution of life.

The Simeis 147 remnant is about 150 light-years (LY) in breadth. By comparison, the distance from Earth to the nearest star beyond our Sun, Proxima Centauri, is only four LY. Since the remnant is only about 3000 LY from Earth, it appears quite large—as large as six full Moons—and this photo shows only a part of the remnant. Click here for a newer, wider view of Simeis 147.

Simeis 147 is one of the faintest of the known and catalogued deep-sky objects. It was not discovered until 1952 when two astronomers at the Crimean Astrophysical Observatory at Simeis in the USSR saw it in a plate (glass photographic negative) made with a .64 meter (25") Schmidt Camera.

Takahashi 6-inch refractor with TOA Reducer and an SBIG STL-11000M camera, binned 2x2. Cumulative exposure time was one hour. Made at Gambrills, Maryland, on November 20, 2009. Made on two Macs using TheSkyX SAE; Equinox 6; PHD; Nebulosity; Photoshop CS3; and FITS Liberator.