Stellar Vista Observatory Sky Report for Sept. 6-12

The Sky Report is presented as a public service by the Stellar Vista Observatory, a nonprofit organization based in Kanab, Utah, which provides opportunities for people to observe, appreciate, and comprehend our starry night sky. Additional information is at Send questions and comments to [email protected]

Venus and Mercury shine low in the west after sunset. Brilliant Venus is obvious but Mercury is so near the horizon and sets in twilight that you’ll have a tough time spotting it. The very thin crescent moon, only three days past new and only 12% illuminated by the sun, is just 3° from Venus on the evening of the 9th and they make a pretty pair; perhaps try a photograph if there is an attractive foreground. The star below them is Spica.

The moon moves on, and on the 12th, now near first quarter, it sits 3° above the giant orange star Antares, the heart of Scorpius. Antares is one of three orange stars that are bright enough to see their color (the others are Aldebaran and Betelgeuse); binoculars help bring out the color. Antares is about 550 light years distant and it’s a giant star about 100,000 times as luminous as our sun; if placed at the center of our solar system its surface would extend beyond the orbit of Mars. Antares is an evolved, old supergiant star that has swollen as it approaches the end of its life, and one day, perhaps within the next hundred thousand years, it will explode as a supernova; then it’ll rival the full moon in brightness for several months.

Look earlier in the week before the moon has brightened to see the rest of Scorpius, the Scorpion, which is one of the few constellations to look like what it is named after. Calling these stars a scorpion goes back to Babylon to at least 1,000 BC and certainly much longer, so it’s one of the oldest constellations.

Also before the moon becomes bright notice the Milky Way, stretching in the south from near Scorpius to nearly overhead and on to the northeast, and notice how much brighter it is toward Scorpius. That is the direction of the Milky Way’s center, its widest and brightest part, while Cassiopeia in the opposite direction has fewer stars and is fainter.

Jupiter and Saturn are almost halfway up the southeast sky as darkness falls and you can see them all night. Jupiter is brighter than Saturn, and Saturn is 17° west of Jupiter. This is the best time of the year to observe them with a telescope as they’re at their highest in the early evening, when it’s most convenient to be out.

Written by John Mosley.

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