As we move into autumn, the “Summer Triangle” of stars will start in the western side of the sky as new stars like the “Great Square of Pegasus” climb higher into the east. These are large groups of bright stars whose patterns are easy to find, like the Big Dipper. They serve as stellar guideposts to other stars, constellations, and 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 (comprising the stars Vega, Deneb and Altair), 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.
Speaking of planets, the only planet readily visible in the evening sky is Venus, visible low in the southwest after sunset. It will appear like an exceptionally bright star, but you’ll have to look low to the horizon before evening twilight ends. If you have binoculars, scan slowly to the left of Venus to find a moderately bright reddish star – no it’s not Mars, but the “Rival of Mars” – Antares, the heart of Scorpius the Scorpion.
When it does get completely dark (after astronomical twilight), and if you’re away from most of the city lights, you should notice the faint band of the Milky Way arching high overhead from NE to SW. Many more star clusters and nebulae (clouds of gas and dust) can be found there.
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. M15 is just one of about 200 globular clusters that orbit around the galaxy’s central bulge. It will appear as a tiny fuzzy splotch in binoculars, but telescopes can resolve it into a sphere of many specs of stars. Take your time and look around the edges of the swarm and you’ll see that more and more stars twinkle into view!
Join us at 6:45 pm on Saturday, October 5 and see how to “star hop” your way to the deep sky objects! Tickets are just $2. Members are free.