Bath Astronomers

November Night Sky

This  is a good month for enjoying galaxies in the Andromeda region, as it is pretty well overhead at about 11 pm towards the end of the month when the Full Moon is out of the way.

Star (!) billing, of course, goes to M31, the Great Andromeda Nebula. I usually find it via the distinctive “W” shape of Cassiopeia – just follow the pointy part of the W down by one length of the letter, and a bit to the right, and there it is. If you are in a reasonably dark location, and your eyes are dark adapted, it should be obvious. ( If it is not, then it is a poor night, and you might as well head for the pub!) M31 is the biggest member of our Local Group of galaxies, and , at a distance of 2 million light years, it is by far the most distant object that you can see with the naked eye. When you are looking at it with the naked eye, or binoculars, or indeed most telescopes, you are seeing mainly the bright core of the Galaxy. Once the fainter spiral arms are included through imaging, or patient observing through a large aperture telescope, the whole Galaxy is about 3 degrees, or 6 Moon widths, across. Two details that are easier to see are M31′s two companion galaxies – M32, quite small and bright, close in, and M110, more diffuse and further away.

M31 is also a good starting point for finding the other bright member of our Local Group of Galaxies (apart from our own Milky Way) – this is M33, the Pinwheel Galaxy in Triangulum. Images show why M33 has its name – it has a very impressive set of spiral arms and a relatively small core, and we see it pretty well face on. But, as with M31, these fainter spiral arms can be hard to see, so M33 is much harder to find. However, M31 points the way, as the map below shows. If you start from M31, and head down to the star marked Beta below, and simply keep on going for the same distance, that will take you to M33. It is often easier to see in binoculars, than in a telescope.

Finally, if you have a telescope, for a rather different galaxy experience, head back to the star Beta (Andromedae) I mentioned above, and  look to one side, roughly in the direction of M31, you will see another much smaller (because much more distant) galaxy, NGC 404. This apparent closeness is a mere chance because they are in the same line of sight, but the galaxy is bright enough to be fairly easy to see even in the glare of its apparent neighbour, and that is unusual.

November Galaxies 2016