We’ve been using stars like “The Summer Triangle” as a guidepost to the sky for months now, and it will remain prominent in the western sky through November. But as we progress into autumn, another asterism will serve as our “pointer” for the new season. The “Great Square of Pegasus” is climbing higher into the eastern sky. Like the Summer Triangle, its pattern of bright stars help us to “star hop” to other bright stars and constellations.
Star hopping on smaller portions of the sky also helps us pinpoint specific locations for our telescopes so we can see deep sky wonders like stars clusters and nebulae. For example, in the region of the Summer Triangle we’ll be able to find a famous planetary nebula called the “Dumbbell Nebula.” It represents the expanding shell of dust and gas that was expelled by its dying star thousands of years ago. We can see it as a faint grayish blob of light whose circular shape inspired the term “planetary nebula” even though they have nothing physically in common with planets.
In front of the nose of Pegasus the Winged Horse, we’ll locate the spot for M15, a famous globular star cluster. Sometimes called the Pegasus Cluster, it’s a massive swarm of 100,000 stars. Even at 35,000 light years away, it is still a part of our Milky Way galaxy, one of about 200 globular clusters that orbit around the galaxy’s central bulge.
Jupiter rises late in the eastern sky but will be coming up earlier and earlier as fall progresses. It will be the brightest star-like object in Taurus, located below and left of the famous Pleiades Star Cluster (the “Seven Sisters).