A lengthy lunar eclipse

THE SOLAR SYSTEM’S CHANGING LANDSCAPE AS IT APPEARS IN EARTH’S SKY.

A total eclipse of the Moon greets observers of the sky this month. It’s perfectly timed for the evening of May 15 across the U.S. and the early morning hours of May 16 in Europe, Africa, and the Middle East. Meanwhile, catch Mercury early in May, ending its period of best evening viewing this year for Northern Hemisphere skygazers. It quickly sinks out of view. This leaves planetary observers to enjoy the pre-dawn treat of four visible planets, starting out with Venus and Jupiter spectacularly close, while Saturn and Mars continue to climb higher in the morning sky.

Mercury shines at magnitude 0.5 on May 1, hanging 11° high in the western sky 45 minutes after sunset. The Pleiades (M45) linger nearby and become visible as twilight fades. A 1.2-day-old crescent Moon sits 7° below Mercury and M45 — look for its very slender crescent just above the horizon. Once the sky is dark enough, look also for the binocular Comet C/2021 O3 (PANSTARRS) 3.5° to the right (northwest) of the Pleiades. The comet’s path will take it due north into Perseus, and it should be visible over a few nights — but its brightness will certainly surprise observers, either because it is fainter or brighter than predicted, so keep an eye on it.

The crescent Moon slides farther along the ecliptic by

May 2, now higher than Mercury (4.5° away). It’s a beautiful sight with the Hyades and 1st-magnitude star Aldebaran, the Moon, Mercury, and M45 spanning the western horizon — one not to be missed.

Watch Mercury each evening for as long as you can. The small planet drops to magnitude 1.4 by May 7, becoming harder to spot. It reaches inferior conjunction with the Sun on May 21, and will reappear by next month in the morning sky.

Late on May 15, observers across the U.S. will be greeted with a total eclipse of the Moon, the first of two this year (the second one occurs early on the morning of Nov. 8). The

Y. BELETSKY (LCO)/ESO This stunning trick of perspective makes it look as if the European Southern Observatory’s Very Large Telescope is shouldering the weight of Earth’s eclipsed satellite. A longer-than-usual total lunar eclipse will delight skywatchers this month.

ALL ILLUSTRATIONS: ASTRONOMY: ROEN KELLY On May 2, Mercury, the Moon, and the Pleiades all put in an appearance after sunset. If Comet PanSTARRS doesn’t disappoint, you’ll find it 8° north of Mercury.