Here is the transcript for my podcast about how to see the Summer Triangle, the North America Nebula, and the Bow-Tie Nebula during the next few days.
Check out the Astronomy.com's interactive star chart to see an accurate map of your sky. It'll help you locate some of this week's key targets. Astronomy magazine subscribers have access to a slew of cool functions.
Targets for August 29-September 4
Naked-eye: Summer Triangle
Small telescope: North America Nebula
8-inch or larger telescope: Bow-Tie Nebula
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The Summer Triangle, the North America Nebula, and the Bow-Tie Nebula are visible in the next few days. We’ll help you find them in this week’s Astronomy magazine podcast.
Triple treat
To find our first object — which you can see with your naked eyes — I’m giving the easiest instructions ever: Go outside after twilight ends and look up. If your sky is clear, you’ll see three bright blue stars making a large right triangle. Astronomers call this group the Summer Triangle because, during the summer in the Northern Hemisphere, it’s visible all night long.
The Summer Triangle isn’t a constellation. Rather, it’s an asterism. What’s the difference? A constellation is one of 88 star patterns that astronomers recognize as “official.” Constellations cover the sky leaving no gaps, and there’s no overlap between any two groups.
An asterism, on the other hand, is a pattern of stars that makes a picture, but that is not one of the 88 constellations. Constellations can contain asterisms. A good example is the constellation Ursa Major the Great Bear. It contains the familiar asterism of the Big Dipper.
Asterisms also may come from several constellations. Such is the case with the Summer Triangle. Its three stars come from three separate constellations.
The brightest of the three, Vega, is part of Lyra the Harp. Southeast of Vega is Altair, in Aquila the Eagle. Finally, to the north-northeast of Altair sits Deneb, in Cygnus the Swan.
I’ve seen that figure somewhere
Our second object is a great target for binoculars or small telescopes. It’s the North America Nebula, also known as NGC 7000. The “NGC” designation refers to a famous catalog of deep-sky objects called the New General Catalog, which first appeared in 1888.
To find the North America Nebula, look 3° east of Deneb. (Yes, it’s the same Deneb that’s in the Summer Triangle.) The North America Nebula measures 2° across, so if you’re using a telescope, start with the eyepiece that gives you the widest field of view.
You may not see the whole continent at first glance. Start by finding the brightest part — Mexico — then patiently try to see the rest. A nebula filter will definitely help your search.
That’s no planet
Later in the evening, those of you with 8-inch or larger telescopes who observe under a dark sky can search for a planetary nebula called the Bow-Tie Nebula, also known as NGC 40.
The Bow-Tie Nebula sits 5.5° east-southeast of the star marking the head of Cepheus the King, magnitude 3.2 Gamma Cephei. Most planetary nebulae glow with a green or blue color. The Bow-Tie, however, shines with a pale-red glow.
Through a 12-inch scope, NGC 40’s disk shows several bright knots lying toward the southeast and northwest. Increase the magnification to 200x, and look for a dark cavity between the shell and the central star.
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Previous transcript — August 22, 2008: Jupiter, M57 (Ring Nebula), NGC 1