The Ring Nebula (Lyra) As the summer draws to a close we are still able to enjoy some of the sights of the summer sky over in the west after sunset. One of the bright stars low in the west is Vega in the constellation Lyra, and just a little distance away you will find the Ring Nebula, a star at the end of its life. At a distance of 2,300 light-years from Earth it gives us a great view of what will happen to our sun when it dies in around 5 billion years time. Average-mass stars eventually lose the ability to hold on to their outer layers that slowly, over many thousands of years, get shed into space. That's what we can see in the Ring Nebula -- its outer shells slowly leaving the star.
The Dumbbell Nebula (Vulpecula) Similar in nature to the Ring Nebula, the Dumbbell Nebula in Vulpecula is another example of a star at the end of its life. Complex magnetic fields and rotational effects have shaped the departing shells of gas into its characteristic dumbbell shape. To give you an idea of scale, the nebula extends for just under 0.75 light-years from the the star's core. It can be found at the southern end of the Summer Triangle and even modest amateur telescopes reveal its delicate structure.
M15 (Pegasus) It surprises many people when they realize the stars can often be found in clusters. M15 in Pegasus is one of the better examples of a "globular cluster" in the northern sky. Stellar clusters of this type are common in the Universe and are typically found in a gigantic halo surrounding galaxies. M15 is just one of the clusters that orbit the Milky Way. Thought to be around 13.2 billion years old, it's one of the oldest known clusters in the Universe.
NGC7331 (Pegasus) A member of the 'New General Catalogue', NGC7331 in the constellation Pegasus is one of the few galaxies that looks like more than just a smudge through amateur telescopes. It's a spiral galaxy 40 million light-years away which means we see it as it was 40 million years ago! Unlike most galaxies, the central bulge seems to be rotating in the opposite direction to the rest of the galaxy. It's not known what mechanism has caused this although it is possible that infalling material has a part to play.
The Andromeda Galaxy (Andromeda) Probably the most spectacular object photographically and easiest to find visually is the mighty Andromeda Galaxy. It's the nearest major galaxy to our own at a distance of 2.3 million light-years, which means its actually pretty big in the sky, much larger than the size of the full moon. While it is visible to the unaided eye from a dark site, it's often unimpressive through a telescope as only the central core is prominent. Images taken by Hubble and powerful ground-based telescopes show the true beauty of our nearest galactic neighbor.
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