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Moon, Saturn and Antares on September 18


Tonight for September 18, 2015

The constellation Scorpius. From the Northern Hemisphere, it’s highest up in the evening on hot summer nights of July and August. It’s heading into the sunset glare every year in late September.

For us in the Northern Hemisphere, summer is fading away, and the constellation Scorpius the Scorpion – which we associate with summertime – is visible only at nightfall and early evening. But the night of September 18, 2015, presents a good opportunity to view Scorpius one more time, or at least to glimpse the Scorpion’s Heart, the star Antares to the east of the September 18 moon and Saturn.

The chart at the top of this post shows the sky scene from the vantage point of North America this Friday evening. If you’re elsewhere in the world, the orientation of these objects with respect to each other might not be identical … but it will be similar. Take a look!

Golden Saturn and the red star Antares – and the moon – all set around mid-evening at mid-northern latitudes. In the Southern Hemisphere, the moon, Saturn and Antares shine higher up in the sky as darkness falls and stay out later after dark.

Recommended almanacs can help you find setting times for the sun, moon and planets in your sky

The Scorpion is one of the few constellations that looks like the creature for which it was named. It’s that curved “tail” of stars looping down toward the southern horizon that does the trick. The star Antares is sometimes called the Heart of the Scorpion. It is a fiery red star, one of the brightest stars in the sky, with a reputation for twinkling fiercely. The fierce twinkling no doubt stems from the fact that, to us in the Northern Hemisphere, Antares arcs across the southern sky and is often seen low in the sky. And when we look low in the sky, we’re looking through a thicker-than-usual mass of Earth’s atmosphere. The atmosphere, of course, is what causes stars to twinkle.

The September 18 waxing crescent moon, as seen from North America, is about 27% illuminated by sunshine. In the world’s Eastern Hemisphere – Europe, Africa, Asia, Indonesia, Australia and New Zealand – the waxing crescent exhibits a little thinner phase and lies somewhat farther west of Saturn than it does in North America.

No matter where you live, the moon – as always – is moving eastward in front of the background stars (and planets) of the Zodiac, and heading toward Antares as we speak.

The moon always moves eastward in front of the constellations of the Zodiac.. The green line depicts the ecliptic - the sun's annual pathway in front of the zodiacal constellations.

The moon always moves eastward in front of the constellations of the Zodiac.. The green line depicts the ecliptic – the sun’s annual pathway in front of the zodiacal constellations.

Bottom line: Look for the waxing crescent moon near the planet Saturn and star Antares, the Scorpion’s Heart, on the evening of September 18, 2015.

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