Overview
On the evening of May 20, skywatchers across much of the globe will witness a striking celestial pairing: the waxing Moon glides close to Jupiter, the largest planet in our solar system. This conjunction offers an accessible yet mesmerizing opportunity for anyone with clear skies and a basic curiosity about the cosmos. In this tutorial, you'll learn exactly when, where, and how to observe this dance—no telescope required, though binoculars can enrich the view.
Prerequisites
Timing and Location
The event occurs shortly after sunset on May 20. To see it, you need an unobstructed view of the western horizon. Start looking about 30 to 45 minutes after sunset, when the sky is dark enough for Jupiter to become visible but the moon still rides low. Your local sunset time can be looked up via weather apps or astronomical almanacs. For best results, choose a location away from city lights and tall buildings.
Equipment
- Eyes: The pairing is clearly visible to the naked eye.
- Binoculars (recommended): 7x to 10x magnification will reveal Jupiter's four largest moons (Io, Europa, Ganymede, Callisto) as tiny points of light flanking the planet.
- Telescope (optional): A small telescope at 30–50x shows Jupiter's cloud bands and Great Red Spot if it's facing Earth.
- Star map or app: Helps confirm you're looking at the right object. Free apps like Stellarium or SkyView are excellent.
Step-by-Step Instructions
Step 1: Determine Sunset and Moonrise Times
Use a reliable source (e.g., timeanddate.com) to find the sunset time for your specific latitude and longitude. The moon will already be up at sunset on May 20, since it's a waxing crescent. Jupiter follows the sun by only a few hours, so it sets soon after the sky darkens. Mark the golden window: approximately 30–60 minutes after sunset.
Step 2: Find the Moon
Go outside as twilight deepens. Look toward the western sky—the moon will be a slender crescent, about 20–25 percent illuminated. It's unmistakable: the brightest object in that region of the sky. Use the moon as your guidepost; Jupiter will be just to its lower left (or upper right, depending on your location—check an app for the precise orientation).
Step 3: Locate Jupiter
Once you've spotted the moon, let your eyes scan a few degrees to the left and slightly downward (for Northern Hemisphere observers). Jupiter shines brilliantly, outshining every star in that part of the sky. Its steady, non-twinkling white light distinguishes it from background stars. If you're using binoculars, point them at the moon, then shift slightly left until Jupiter pops into view.
Step 4: Enhance Your View (Optional)
If you have binoculars, brace them against a wall or use a tripod adapter for stability. Focus carefully—Jupiter will appear as a tiny disk, not a point. The four Galilean moons will be arrayed in a line near the planet. With a telescope, increase magnification to 50x to see subtle cloud bands. The Great Red Spot may not be visible without high power and good seeing, but enjoy the disk itself.
Step 5: What to Look For
- Angular separation: On May 20, Jupiter and the Moon are about 4–5 degrees apart (roughly the width of your three middle fingers held at arm's length).
- Color contrast: Note the moon's warm, grayish glow against Jupiter's cool white.
- Dark sky features: On the moon's unlit side, you might glimpse earthshine—sunlight reflected from Earth faintly illuminating the dark portion.
- Time progression: Watch over 15–20 minutes as the pair sets lower, eventually vanishing below the horizon.
Common Mistakes
Mistake 1: Looking Too Early
If you go outside right at sunset, the sky is too bright—Jupiter will be invisible. Wait at least 30 minutes. Conversely, waiting too long (more than 90 minutes after sunset) may cause both objects to set or become too low.
Mistake 2: Confusing Planets
Other bright planets like Venus or Mars might be elsewhere in the sky. In May 2024, Venus sets earlier, while Mars is in the morning sky. Jupiter is the only bright planet near the moon that evening. If you see a bright 'star' far from the moon, it's probably a star (e.g., Procyon). Use a star map to double-check.
Mistake 3: Forgetting Binoculars
Many observers assume they need a telescope to see more. Actually, binoculars are ideal for this event—Jupiter's moons are an easy target. If you skip them, you miss a lovely detail. Bring them along even if you think you won't need them.
Summary
On May 20, the waxing moon and Jupiter perform an elegant pas de deux low in the western sky after sunset. With no special gear, you can enjoy their proximity; with binoculars, Jupiter's moons come into view. Plan your viewing time, avoid common pitfalls like early or late attempts, and you'll be rewarded with a memorable celestial sight.