Special to CosmicTribune.com, May 19, 2024

Excerpts from weekly Sky&Telescope report.

SUNDAY, MAY 19

■ The Moon continues to illuminate Virgo’s part of the sky. Early this evening look about 3° or 4° lower left of the Moon for Spica, Virgo’s brightest star. By midnight the Moon moves closer to Spica, which then will be directly to its left.

MONDAY, MAY 20

■ Now Spica shines upper right of the Moon. Much farther to their upper left (three fists) is brighter Arcturus.

■ The Arch of Spring still spans the western sky in late twilight, but it’s getting lower. Pollux and Castor form its top: They’re lined up roughly horizontally in the west-northwest, about three finger-widths at arm’s length apart. Look far to their lower left for Procyon, and farther to their lower right for 2nd-magnitude Menkalinan and then bright Capella.

TUESDAY, MAY 21

■ Have you ever seen Alpha Centauri? At declination –61° our brilliant, magnitude-zero neighbor is permanently out of sight if you’re north of latitude 29°. But if you’re at the latitude of San Antonio, Orlando, or points south, Alpha Cen skims just above your south horizon for a little while late these evenings.

WEDNESDAY, MAY 22

■ The Moon this evening is ½ day before full (it’ll be exactly full at 9:53 a.m. EDT Thursday morning), so “full Moon” applies equally to both this evening and tomorrow evening.

The Moon each month takes three or four days to walk the wide gap from Spica to Antares.

THURSDAY, MAY 23

■ Full Moon occults Antares. Tonight the brilliant round Moon passes right over Antares for the southeastern U.S., Central America, northeastern South America, the Caribbean, and parts of west and central Africa. Elsewhere the Moon performs a near miss.

That’s not Antares but Aldebaran, similar in brightness and color, about to be occulted in blue-sky daylight on Oct. 2, 2015. Photographer Bob King wrote, “I took this picture with an older iPhone through a 10-inch scope, shortly before the Moon occulted Aldebaran an hour after sunrise.” The Moon was waning gibbous.

Telescope users in Miami will see Antares disappear at 9:12 p.m. EDT when the Moon is just 6° above the southeast horizon. Then Antares will reappear from behind the Moon’s other side at 10:18 p.m. EDT, when the Moon has climbed to 18° high.

Wherever the occultation happens, the star will disappear smack on the Moon’s bright edge, then will reappear from behind the extremely thin “dark crescent” of night on the other edge. So yes, in both cases you will definitely need a telescope.

Antares is a double star; its companion, magnitude 5.4, lurks a mere 2.7 arcseconds west of Antares A. The blazing moonlight is likely to overwhelm Antares B, but see if you can detect it emerging from behind the Moon’s dark limb just a few seconds before the magnitude-1.1 primary pops out.

FRIDAY, MAY 24

■ Vega is the brightest star shining in the east-northeast after dark. Look lower left of it, by about two fists at arm’s length, for Deneb, less bright. Those stars are two thirds of the Summer Triangle.

So where’s the third? It’s Altair. With summer still four weeks away (astronomically speaking), it stays below the eastern horizon until somewhat after dark. Watch for it to clear the horizon three or four fists at arm’s length to Vega’s lower right.

■ Have you tried for Mercury in the dawn? It’s very low in the east a half hour before sunrise, as indicated below. This is about your last chance at Mercury this apparition. Bring binoculars.

Mercury has been brightening but sinking lower in the dawn. Modest Mars, less low, guides the way. This morning they’re 25° apart.

SATURDAY, MAY 25

■ Capella sets low in the northwest not very long after dark, depending on your latitude. That leaves Vega and Arcturus as the brightest stars in the evening sky. Vega shines in the east-northeast. Arcturus is very high toward the south.

Right after full dark and before the Moon rises, look a third of the way from Arcturus to Vega for semicircular Corona Borealis, with 2nd-magnitude Alphecca as its one moderately bright star.

Two thirds of the way from Arcturus to Vega is the dim Keystone of Hercules, now lying almost level.

Use binoculars or a telescope to examine the Keystone’s top edge. A third of the way from its left end to the right is 6th-magnitude M13, one of Hercules’s two great globular star clusters. In binoculars it’s a tiny glowing cotton ball. A 4- or 6-inch scope begins to resolve some of its speckliness. Located 22,000 light-years away far above the plane of the Milky Way, it consists of several hundred thousand stars in a swarm about 140 light-years wide.

SUNDAY, MAY 26

■ Back to Vega getting high in the east-northeast. Look for its faint little constellation Lyra, the Lyre, hanging down from it with its bottom canted to the right.

■ The waning gibbous Moon rises around midnight. Once it’s well up, cover it with your fingertip to help reveal that it’s in the middle of the Sagittarius Teapot.

  May 19-26: Full Moon occults Antares on May 23, The Sky