Challenge: Find These Stars

Look at the pattern of stars below. What does it look like to you?

What do you see in this pattern of stars?
What do you see in this pattern of stars?

It’s a shame that the stars of this constellation are not brighter, because it is actually one of the constellations that looks like what it is supposed to be. This is the constellation Scorpio, the scorpion, one of the original signs of the Western Zodiac. July is the best month to see Scorpio from Chicago and other cities in the Northern Hemisphere. Unfortunately, because of its southerly location, it never gets very high above the horizon here; you will have an easier time seeing it, for example, in the southern United States.

Your challenge: find as many of these stars as you can amidst the glow of the city lights.

Wait at least an hour after sunset (9:30 pm Central time should be good enough) and look to the south. You will see a bright orange star, not very far above the horizon. This is Antares, the brightest star in Scorpio, and one of the 15 brightest stars visible from Chicago. Its orange color resembles that of the planet Mars, and that is where the star got its name: Antares means “rival of Ares” (Ares is the Greek name for the Roman god of war, Mars). Antares is star number 1 in the diagram below.

If you go observing on Thursday night (July 18), the moon will be in Scorpio (near star number 2 below). This will make it easy for you to look in the right area for the stars of Scorpio, but the moon is getting close to full, and its bright light will wash out the dimmer stars.

How many of these stars can you find in the city?
How many of these stars can you find in the city?

On Tuesday night, I was able to see five of Scorpio’s stars (1 through 5 in the diagram). Stars 2 and 3 were fairly easy for me to see, but both are quite a bit dimmer than Antares. Star 2 is called Acrab (from the Arabic word for scorpion) and star 3 is called Dschubba (from the Arabic word for forehead–of the scorpion, presumably). Acrab and Dschubba are as bright as some of the stars in the Big Dipper.

After that, things got tricky for me. Stars 4 and 5 were about at the limit of my eyesight. Although star 4 (called Pi Scorpii) is the dimmest of the 6 stars I labeled, I was able to spot it occasionally. Star 5 (called Epsilon Scorpii) is actually brighter than both stars 2 and 3, but I still had a hard time seeing it. The problem is the glow of the city lights. Star 5 (Epsilon Scorpii) is closer to the horizon than the first four stars on the diagram, and so it is closer to the city glow. This problem is especially hard to overcome on the north side of Chicago (where I live), because looking south means looking toward the Loop and the lights of the downtown skyscrapers.

This brings us to star 6, which I could not find. Star 6, called Shaula (from the Arabic for “the raised tail”) is actually the second brightest star in Scorpio, so it should be easy to find. Its position close to the horizon makes it very susceptible to the bright city glow, and I think that is why I could not see it Tuesday night.

How many of these can you see? Can you see any of the stars I did not label? Give yourself at least half an hour outside to acclimate your eyes to the night. Find as dark a spot as possible; this can be a challenge as there are street lights everywhere in the city, but parks and unlit athletic fields are good locations. Finally, when trying to find a dim object in the sky, don’t look directly at the spot you want to observe. Your peripheral vision is more sensitive to low light.

Give it a try later this week or this month, and share your findings in the comments. Scorpio will be in good view for another couple of weeks, before it dips below the horizon.

(Diagrams based on screen shots from Stellarium.)

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