Friday, May 20
Wednesday, May 13
■ 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.
■ Before and during early dawn Thursday and Friday, the waning Moon accompanies Mars as shown above.
Thursday, May 14
■ A gigantic asterism you may not know about is the Diamond of Virgo, some 50° tall and extending over five constellations. It now stands upright in the south after dark. 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 tail-tip of Leo. And then back to Spica.
The bottom three of these stars, the brightest, form a nearly perfect equilateral triangle. Maybe we should call this the "Spring Triangle" to parallel those of summer and winter?
■ Last-quarter Moon (exact at 10:03 a.m. Eastern Daylight Time). Tonight the Moon rises very late, around 3 a.m. Friday morning daylight-saving time, by which time it will be visibly a little past first quarter, as shown above. And Mars will be upper right of it.
Friday, May 15
■ A naked-eye Venus challenge! All week, the large, thin crescent shape of Venus is easy to discern with even a very small telescope or good, steadily braced binoculars. But can you resolve its crescent with your unaided eyes? Mere 20/20 vision isn't good enough; success may await the eagle-eyed with 20/15, 20/12, 0r (rare) 20/10 vision. Try during different stages of twilight before the sky is too dark and Venus's glare becomes overwhelming. Look long and carefully and report your results to Sky & Telescope's Bob King,
nightsky55@gmail.com, as told in the May issue, page 49.
You may improve your chances by sighting through a clean, round hole in a stiff piece of paper 1 mm or 2 mm in diameter (try both). This will mask out optical aberrations that are common away from the center of your eye's cornea and lens.
One person who apparently succeeded was Edgar Allan Poe. An amateur astronomer since boyhood, he used a naked-eye sighting of Venus's crescent as the central event in his poem "Ulalume" (1847). Before dawn, a bereaved lover roams an October woodland "with Psyche, my soul." Ahead of them low in the east, where Leo always ascends in mid-autumn, they witness the new-risen Venus, star of romantic love in Roman mythology, coming "up through the lair of the Lion." Poe refers to the planet as Astarte, the wilder, more wanton Greek version of the Roman Venus-goddess:
At the end of our path a liquescent
And nebulous lustre was born,
Out of which a miraculous crescent
Arose with a duplicate horn—
Astarte's bediamonded crescent
Distinct with its duplicate horn.
Poe compares its passionate brilliance to cooler, less dazzling Dian, the horned crescent Moon, and urges Psyche forward:
Let us on by this tremulous light!
Let us bathe in this crystalline light!
But Psyche, who knows better, is terrified, and this being Poe, it doesn't end well.