Sky ArchiveTonight

Moon, Saturn, Mars on May 4 to 6

These next several mornings – May 4, 5 and 6, 2018 – the bright waning gibbous moon will be putting a damper on the predawn Eta Aquariid meteor shower. But this bright moon will show you Saturn and Mars in the starry sky. Saturn and Mars are easily as brilliant as 1st-magnitude stars, so you should have no trouble seeing them in the moon’s glare. The only requirement (besides a clear sky) will be to stay up very late, or to rise before the sun on these mornings. Saturn and Mars will be the two brilliant “stars” near the moon.

Both Saturn and Mars are shining in front of the constellation Sagittarius the Archer right now. Saturn will stay within Sagittarius’ boundaries for the rest of the year, but – by mid-May 2018 – Mars will cross over into the neighboring constellation to the east, Capricornus the Sea-goat.

Still, Sagittarius – with its famous “Teapot” asterism – is a great constellation to learn to identify. It marks the direction toward the center of our Milky Way galaxy, and many wonderful binocular sights lie in this part of the sky. Let the moon show you bright planet Saturn over the next few days. Then let Saturn be your guide to the constellation Sagittarius for the rest of 2018.

This sky chart, via IAU, highlights the Teapot asterism in western Sagittarius. The sun resides in the constellation Sagittarius on the December solstice (where the ecliptic crosses 18 hours of right ascension). Right ascension on the sky’s dome is the equivalent of longitude here on Earth.

The sun will enter the constellation Sagittarius on December 18, 2018. It’ll remain in front of Sagittarius until January 19, 2019, at which time the sun will enter the constellation Capricornus the Sea-goat. But you can’t see Sagittarius in December and January. That’s because the sun is in front of this constellation during a Northern Hemisphere winter or Southern Hemisphere summer.

Once the moon leaves this part of the sky, Saturn serves as your faithful guide to the constellation Sagittarius for many months to come. Although modern eyes have a tough time seeing Sagittarius as a centaur with a drawn-out bow and arrow, the Teapot asterism in western Sagittarius is fairly easy to make out on a dark night. What’s more, you can see the starlit boulevard of stars known as the Milky Way – an edgewise view of our home galaxy – passing right though the Teapot in a dark sky free of moonlight and pesky artificial lights.

Use the planet Saturn to locate the Teapot asterism in 2018.

If you’re not one to wake up early, simply wait for another month or two. By that time, Saturn and the Teapot will be yours to behold in the evening sky.

Bottom line: If you’re an early bird, get up before dawn on May 4, 5 and 6, 2018, to see the moon, Saturn and Mars – and possibly some of the brighter Eta Aquariid meteors in moonlight.

May 3, 2018
Sky Archive

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Bruce McClure

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