This Week’s Sky – July 24 – 30

Sunday, July 24

• The tail of Scorpius lies low due south right after dark. Look for the two stars especially close together in the tail. These are Lambda and fainter Upsilon Scorpii, known as the Cat’s Eyes. They’re canted at an angle; the cat is tilting his head and winking.

The Cat’s Eyes point… west (right) by nearly a fist-width toward Mu Scorpii, a much tighter pair known as the Little Cat’s Eyes. It takes very sharp vision to resolve Mu without binoculars!

Monday, July 25

• The Delta Aquariid meteor shower, modest but very long-lasting, should most active for the next week or so. Under a very dark sky, you might see a dozen Delta Aquariids per hour between midnight and the first light of dawn. The light of the waning Moon will present less interference each morning.

Tuesday, July 26

• Last-quarter Moon (exact at 7:00 p.m. EDT). The Moon rises around midnight or 1 a.m. daylight-saving time tonight, positioned near the Knot of Pisces. By early dawn Wednesday morning it stands high in the southeast.

• Are you checking the location of Nova Ophiuchi 1998, as described on page 51 of the July Sky & Telescope? It may re-explode to 10th magnitude any year now, and someone will be the first to discover this….

The consolation prize on any night are the five globular clusters in its immediate vicinity, as charted on that page.

Wednesday, July 27

• We’re not yet halfway through summer, but already W-shaped Cassiopeia, a constellation of fall and winter evenings, is climbing up in the north-northeast as evening grows late. And the Great Square of Pegasus, emblem of fall, comes up to balance on one corner just over the eastern horizon.

By the first light of dawn the Great Square stands very nigh in the south, almost overhead, as shown above.

Thursday, July 28

• The waning crescent Moon occults Aldebaran for observers in much of eastern North America. It will also occult the fainter, nearby star-pair Theta1 and Theta2 Tauri for some of the region. See your August Sky & Telescope, page 50, or the extensive timetables online for all three occultations.

Nearly a month later, on August 25th, the Moon will occult Aldebaran in daylight, as also briefly described in the August Sky & Telescope article.

Friday, July 29

• Bright Vega now passes almost straight overhead around 11 p.m. daylight-saving time, depending on your location. As with all star configurations, you’ll see it happening two hours earlier every month.

Saturday, July 30

• As summer proceeds, Scorpius shifts westward from its highest stance in the south just after dark, and Sagittarius moves in from the east to take its place. So we’re entering prime time for the profusion of Messier objects in and above Sagittarius. How many can you locate with binoculars?

Start with M8, the big Lagoon Nebula. It’s 6° above the spout-tip of the Sagittarius Teapot.


Want to become a better astronomer? Learn your way around the constellations! They’re the key to locating everything fainter and deeper to hunt with binoculars or a telescope.

This is an outdoor nature hobby. For an easy-to-use constellation guide covering the whole evening sky, use the big monthly map in the center of each issue of Sky & Telescope, the essential guide to astronomy.

All descriptions that relate to your horizon — including the words up, down, right, and left — are written for the world’s mid-northern latitudes. Descriptions that also depend on longitude (mainly Moon positions) are for North America.

Eastern Daylight Time (EDT) is Universal Time (UT, UTC, or GMT) minus 4 hours.


“This adventure is made possible by generations of searchers strictly adhering to a simple set of rules. Test ideas by experiments and observations. Build on those ideas that pass the test. Reject the ones that fail. Follow the evidence wherever it leads, and question everything. Accept these terms, and the cosmos is yours.”

— Neil deGrasse Tyson

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