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Double cat's eyes in the skies

Starwatch — Mike Lynch column sig

We have two pairs of cat’s eyes this summer, one much brighter than the other. The brighter pair is made up of the bright planets Jupiter and Saturn, appearing in the Rochester southeast evening skies. Even in areas of horrible light pollution, you can’t miss them. Jupiter is the brighter of the pair on the upper left. These two solar system giants are the closest they’ve been to each other in the sky in 20 years. They’re also tremendous telescope targets, even in smaller scopes. Just remember to take long, continuous looks to give your eye a chance to get used to the light level in your eyepiece. That will help you see more details on the dynamic duo of the solar system.

The other pair of cat’s eyes in the sky are not as bright, but they are a lot of fun to look for in the classic summer constellation Scorpius the Scorpion. Scorpius isn’t far away from Jupiter and Saturn in the low southern sky as evening begins.

Scorpius the Scorpion is one of my favorite constellations because it’s one of the few that actually looks like what it’s supposed to be. The only problem is that the great scorpion never gets all that high in our sky in Southeastern Minnesota. In fact, part of the tail of the scorpion never gets above our horizon. Stargazers in the southern half of the U.S. have a better view of Scorpius, as the celestial beast takes a much higher track in the sky. I highly recommend checking out Scorpius if you’re down south this summer.

Nonetheless, even in more northern latitudes Scorpius is still a great attraction in the summer sky. It lies within the Milky Way band that runs from the northern to southern horizon. It is made of the combined light of billions of distant stars that lie in the thicker plane of our home Milky Way Galaxy. Scorpius lies nearly in the direction of the center of our galaxy, so the Milky Way band is a little brighter there, especially if you see it in the dark countryside on a moonless night.

The brightest star in Scorpius is the bright brick-red star Antares at the heart of the beast. It’s the brightest star in that part of the heavens. To the right of Antares, you’ll see three dimmer stars in a vertical row that make up the Scorpion’s head. To the lower left of Antares, look for the long, curved tail of the beast. Antares has a definite reddish hue. That’s because it’s a red supergiant star. Antares is cooler than our own sun, with a surface temperature of close to 6,000 degrees Fahrenheit, compared to 10,000 Fahrenheit. The red hue of Antares is also reflected in its name.

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Antares is over 6 hundred million miles in diameter! Our sun isn’t even a million miles in girth. If Antares replaced the sun as the center of our solar system, the outer edge of Antares would extend beyond the orbit of Mars. We would be living inside Antares!

The tail of Scorpius is the home of the dimmer pair of “cat’s eyes” this summer. Unlike Jupiter and Saturn, we see these feline eyes every year. They are made up of two moderately bright stars, Shaula and Lesath, and mark the stinger of the scorpion. This pair of cat’s eyes is a bit of a challenge because they’re also very low in the sky, super close to the horizon. Trees can easily block your view, so you have to look for them in a location where you can see all the way down to the actual horizon.

With the naked eye, these two stars aren’t really all that impressive, and to be honest with you, they’re not all that much better with a telescope. Despite that, they are actually a couple of really impressive stars. Shaula, a little over 700 light-years away, is the brighter of the two of these cat’s eyes. It’s at least 6 million miles wide. Its surface temperature is over 40,000 degrees, more than five times as hot as the sun, and it kicks out more than 35,000 times more light than our home star. Lesath, the dimmer right eye of the cat, is almost as impressive as Shaula. It’s nearly 600 light-years away, and slightly smaller, cooler and dimmer, but still a mighty star in our Milky Way Galaxy.

Even though they’re a lot dimmer than the bright cat’s eyes of Jupiter and Saturn, Shaula and Lesath dwarf them!

Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis/St. Paul and is author of the book, “Stars, a Month by Month Tour of the Constellations” published by Adventure Publications. Send questions to mikewlynch@comcast.net .

The Rochester Astronomy Club welcomes new members and puts on public star parties. Their website is rochesterskies.org .


SW DIAGRAM FOR AUG 14-16, 2020.jpg
(Courtesy Mike Lynch)

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