This week, skywatchers have a rare chance to observe the moon’s orbital motion in real time as a young crescent passes Venus and then Jupiter in the western sky after sunset. On May 18, the moon is just 2.4 days old, with only 6.2% of its surface illuminated, appearing close to the bright planet Venus. Jupiter sits slightly higher and dimmer, with the stars of Gemini—Castor and Pollux—faintly visible below.

The alignment unfolds over several evenings, with the moon moving eastward and growing in illumination each night as its angle to the sun changes. Observers in the southern hemisphere have an advantage, as the ecliptic—the orbital plane of the sun, moon, and planets—tilts more steeply at this time of year, lifting the conjunction higher above the horizon.

For the best view, find a location with an unobstructed western horizon. The sequence offers a quiet but vivid illustration of celestial mechanics, visible without telescopes. No special equipment is needed, just clear skies and timing shortly after sunset.