Special to CosmicTribune.com, May 11, 2025

Excerpts from weekly Sky&Telescope report.

SUNDAY, MAY 11

■ What is the oldest thing you have ever seen? For everyone in the world it’s at least the Sun and other objects of the solar system, age 4.6 billion years. (Virtually everything on or a little way under Earth’s surface is much younger.)

Next is Arcturus, which most people have surely seen whether they know it or not, since it’s one of the brightest stars in the sky. It’s a Population II orange giant, age about 7 billion years, just passing through our region of the Milky Way.

Amateur astronomers have globular clusters. Most are older still, at least in part. White dwarfs in familiar M4 in Scorpius have dated it (or at least some population of it) at 12.7 ±0.7 billion years old.

MONDAY, MAY 12

■ Full Moon this evening (it’s exactly full at 12:56 p.m. EDT today). The Moon rises in the southeast about a half hour after sunset. Once it’s well up and the night is dark, spot orange Antares and the other, whiter stars of upper Scorpius to the Moon’s lower left.

TUESDAY, MAY 13

■ The Moon, nearly a day past full, rises around the end of nightfall closely accompanied now by Antares. As they climb higher and cross the sky through the night, watch them draw farther apart as the Moon moves eastward along its orbit.

The other stars of upper Scorpius also lie in the Moon’s background. Cover the glary Moon with your fingertip to help see them.

WEDNESDAY, MAY 14

■ A gigantic asterism you may not know about is the Great Diamond, some 50° tall and extending over five constellations. It now stands upright in the southeast to south after dusk.

Start with Spica, its bottom. Upper left from Spica is bright Arcturus. Almost as far upper right from Arcturus is fainter Cor Caroli, 3rd magnitude. The same distance lower right from there is Denebola, the 2nd-magnitude tailtip of Leo. And then back to Spica.

The bottom three of these stars, the brightest, form a nearly perfect equilateral triangle. This has been called the Spring Triangle to parallel to those of summer and winter.

THURSDAY, MAY 15

■ Jupiter’s 2024-25 apparition is finally drawing toward its close. Jupiter is the “False Evening Star” shining at a bright magnitude –2.0 low in the west-northwest during and after dusk.

But this evening Jupiter performs a noteworthy naked-eye act on its way out. It forms an exact straight line with Taurus’s two horntip stars: Beta Tauri to its upper right and fainter Zeta Tauri closer to its lower left (magnitudes 1.6 and 3.o).

FRIDAY, MAY 16

■ Vega is the brightest star in the east-northeast after dark. Look 15° (about a fist and a half at arm’s length) upper left of Vega for Eltanin, the 2nd-magnitude nose of Draco the Dragon. Closer above and upper left of Eltanin are the three fainter stars that form the rest of Draco’s stick-figure head, also called the Lozenge. Draco always points his nose to Vega, no matter how he’s oriented. Dragons do have a thing for jewels.

The faintest star of Draco’s head, opposite Eltanin, is Nu Draconis. It’s a fine, equal-brightness double star for binoculars (separation 61 arcseconds, both magnitude 4.9). The pair is 99 light-years away. Both are hot, chemically peculiar type-Am stars somewhat larger, hotter, and more massive than the Sun.

■ The brightest asteroid, 4 Vesta, is nicely placed now in a moonless dark sky in late evening. It’s two weeks past opposition and still magnitude 5.9. It’s some 24° below Arcturus, near the Virgo-Libra border about 9° and 10° above Beta and Alpha Librae, respectively. You’ll need the finder chart with Bob King’s article Asteroid Vesta Now an Easy Catch in Binoculars.

If you have a really dark sky, can you detect Vesta now with the unaided eye? It’s pretty much the only naked-eye dwarf planet, and only near its opposition.

SATURDAY, MAY 17

■ And as Vega climbs higher in the evening, its little constellation Lyra, the Lyre, becomes easier to recognize. Lyra’s main pattern hangs down from Vega with its bottom canted to the right. Look for a little equilateral triangle with Vega as its top corner, and a longer parallelogram attached to the triangle’s bottom corner.

SUNDAY, MAY 18

■ This is the time of year when Leo the Lion starts walking downward toward the west, on his way to departing into the sunset in early summer. Right after dark, spot the brightest star fairly high in the west-southwest. That’s Regulus, his forefoot.

Regulus is also the bottom of the Sickle of Leo: a backward question mark about a fist and a half tall that outlines the lion’s forefoot, chest, and mane.

  May 11-18: The rise of Vega, The Sky