The Sky Today on Thursday, July 30: Meteors may shine

The Alpha Capricornid and the Southern Delta Aquariid meteor showers peak overnight, but the bright Moon will run interference.

A wide-angle night sky photograph showing a lone meteor streaking diagonally across the upper portion of the frame against a deep blue, star-filled sky. The Pleiades star cluster is visible as a tight grouping of blue-white stars in the upper right. The foreground is a dark silhouette of rolling hills and trees, with a faint green glow of airglow near the horizon.

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July 29: July’s Full Buck Moon rises

Today marks the convergence of two meteor showers, as both the Alpha Capricornids and the Southern Delta Aquariids peak. But despite the enticing sound of that setup, both showers are quite light, with expected hourly rates of some 5 and 25 meteors per hour, respectively, even at their very best. Plus, there’s the bright, just-past-Full Moon to contend with, and it’s right in the thick of things, hanging near the border of Capricornus and Aquarius.

Despite the unfortunate setup, you can still test your luck overnight and into the early morning of July 31. The Southern Delta Aquariids’ radiant rises in the east around 9:30 P.M. local daylight time and stands highest in the south a few hours after midnight. You’ll want to look in the regions of sky some 40° to 60° on either side of the Full Moon for meteors — this is where the longest trains will appear, and also offers a better chance of a sighting with the Moon out of direct view. It will be a challenge, but any shooting stars you do see should feel doubly rewarding!

Sunrise: 5:57 A.M.
Sunset: 8:15 P.M.
Moonrise: 9:02 P.M.
Moonset: 6:49 A.M.
Moon Phase: Waning gibbous (98%)
*Times for sunrise, sunset, moonrise, and moonset are given in local time from 40° N 90° W. The Moon’s illumination is given at 10 P.M. local time from the same location.

If you’re still up early on the 31st to catch the brightest Southern Delta Aquariid meteors, turn your gaze eastward about an hour before sunrise (roughly 5 A.M. local daylight time) to look for Mercury, now magnitude 0.5 and roughly 4° above the eastern horizon. The small planet should be bright enough to spot easily if your horizon is clear. You may even notice that it stands directly in line with two faint stars, Delta (δ) and Lambda (λ) Geminorum, although these two pinpricks of light will quickly disappear in the encroaching twilight.

If you’re able, try to take a closer peek at the planet with a telescope, as long as you’re mindful of the time and put your instrument away well before sunrise. Under magnification, Mercury’s disk spans 8” on the sky and shows off a slim crescent with 33% of its surface illuminated. Because Mercury has no significant atmosphere, you’re seeing all the way down directly to its cratered surface when you look at it.

Alison Klesman is senior editor of Astronomy magazine. She holds a Ph.D. in astronomy and has studied a variety of topics, from minor planets to supermassive black holes.