Special to CosmicTribune.com, May 4, 2025

Excerpts from weekly Sky&Telescope report.

SATURDAY, MAY 3

■ Now the waxing Moon shines next to Mars. They’re only couple degrees apart. Meanwhile, Mars is less than 1° to the right of the Beehive star cluster, as binoculars or a telescope at low power will reveal.

SUNDAY, MAY 4

■ Mars skims across the northern edge of the Beehive cluster this evening and tomorrow evening.

■ First-quarter Moon (exact at 9:52 a.m. Eastern Daylight Time). By evening for North America the Moon’s terminator will be showing a slight bit of convexity.

After dark the Moon will be under the Sickle of Leo, with Regulus to its left or upper left and Mars (similar to Regulus in brightness but different in color!) farther to the Moon’s right or lower right.

■ The Eta Aquariid meteor shower should be at its peak in the hour or so before the beginning of Monday’s dawn (i.e. from about 3 to 2 hours before sunrise. Also, the Moon will have set by then.) This tends to be the best meteor shower of the year for Southern Hemisphere observers, but it’s poorer for those of us living at mid-northern latitudes due to the placement of its radiant (at the head of Aquarius, the Water Jar asterism). From north of about 40° latitude, almost no Eta Aquariids are seen.

MONDAY, MAY 5

■ The waxing gibbous shines near Regulus, magnitude 1.4. The star is 3° or 4° to the Moon’s right early in the evening, then lower right of it as the night grows late.

TUESDAY, MAY 6

■ As night descends, look high in the west for Pollux and Castor lined up almost horizontally (depending on your latitude) with Mars upper left of them. The two stars, the heads of the Gemini twins, form the top of the enormous Arch of Spring. To their lower left spot Procyon, the left end of the Arch. Farther to their lower right is the other end, formed by 2nd-magnitude Menkalinan (Beta Aurigae) and then brilliant Capella. The whole thing sinks in the west through the evening.

WEDNESDAY, MAY 7

■ 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. Robert H. Baker may have been the first to name the Great Diamond, in his 1954 book When the Stars Come Out.

The bottom three of these stars, the brightest, form a nearly perfect equilateral triangle. We can call this the Spring Triangle to parallel to those of summer and winter.

THURSDAY, MAY 8

■ Whenever the stick figures of the Gemini twins stand upright in the west, as they do after dark for much of the spring, you know that the two-star pattern of Canis Minor lower left of them (Procyon and much fainter Beta CMi) lies horizontal or nearly so. And that the Big Dipper hangs vertically by its handle high in the northwest.

FRIDAY, MAY 9

■ Three zero-magnitude stars shine after dark in May: Arcturus high in the southeast, Vega much lower in the northeast, and Capella in the northwest. They appear so bright because each is at least 60 times as luminous as the Sun and because they’re all relatively nearby: 37, 25, and 42 light-years from us, respectively.

■ Spica, less bright than Arcturus at 1st magnitude, shines a couple degrees lower left of the Moon this evening, as shown below.

The Moon sails below Virgo as waxes from gibbous to nearly full. It’ll be full on the 12th.

SATURDAY, MAY 10

■ Now Spica shines about 10° upper right of the bright evening Moon, as shown above.

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. (Everything on or just 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.

  May 3-11: Three stars bright, The Sky