This Week’s Sky at a Glance, June 30 – July 8


Moon, Saturn, Antares, July 5-7, 2017

Waxing toward full, the Moon passes over Antares and Saturn

Friday, June 30

• First-quarter Moon (exact at 8:51 p.m. EDT). The "star" left of the moon is Jupiter.

• And this evening, the Moon's dark limb will occult (cover) the bright, tight double star Gamma Virginis (Porrima) for much of the U.S. and Canada. The event happens in daylight for the West, twilight for the central longitudes of the continent, and later in darkness for the East. Read more in the July Sky & Telescope, page 50. Here are detailed timetables for hundreds of cities and towns. (The UT date of the event is July 1st.) Plan ahead!

Saturday, July 1

• The Moon in the southwest this evening forms a broad triangle with Jupiter and Spica, as shown above.

Sunday, July 2

• By the time it's fully dark, Altair shines well up in the east. Helping to identify it is its little sidekick Tarazed (Gamma Aquilae), a finger-width above it or to its upper left. (They're unrelated; Altair is 17 light-years from us; Tarazed is about 460.)

Look left of Altair, by hardly more than a fist width, for the compact little constellation Delphinus, the Dolphin.

Monday, July 3

• Look far lower right of the Moon at nightfall for Spica; to the right of Spica shines bright Jupiter. Look far lower left of the Moon for orange Antares; left of Antares is pale-yellow Saturn. These star-and-planet pairs form a roughly symmetrical pattern with the Moon this evening.

Venus, Aldebaran, Pleiades at dawn, July 1, 2017

Venus shines in the east-northeast in early dawn this month . . .

Pleiades, Venus, Aldebaran at dawn, July 8, 2017a

. . . while its background stars climb toward the upper right.

• Before and during dawn for the next few mornings, Venus is passing about 7° south (lower right) of the Pleiades.

• Earth is at the aphelion of its orbit, its farthest from the Sun for the year (only 3% farther than at perihelion in January).

Tuesday, July 4

• Waiting for fireworks to start? Point out some sky sights to folks around you. The waxing gibbous Moon is almost due south at dusk. Look lower left of it for orange Antares, one of the brightest "red" supergiants in the sky. Left of Antares is Saturn. Meanwhile, much farther to the right of the Moon, Jupiter shines brightly in the southwest.

Wednesday, July 5

• The Moon shines above orange Antares this evening. Upper right of Antares, and lower right of the Moon, is the near-vertical row of three stars marking the head of Scorpius. The top star of the row is Beta Scorpii or Graffias, a fine double star for telescopes.

Just 1° below Beta Sco is the fainter, very wide naked-eye pair Omega1 and Omega2 Scorpii, oriented diagonally. Binoculars may show their slight color difference.

Left of Beta by 1.6° is Nu Scorpii, another fine telescopic double. High power in good seeing reveals that Nu's brighter component is itself a close binary, separation 2 arcseconds.

Thursday, July 6

• Catch golden Saturn shining about 3° below the waxing gibbous Moon, as shown above.

Friday, July 7

• The nearly full Moon shines over the Teapot of Sagittarius after dark tonight, as shown above. Look for it carefully for its stars through the moonlight. The Teapot is about the size of your fist at arm's length, with its handle to the left and its spout to the right. Binoculars may help.

Saturday, July 8

• The full Moon is up in the southeast as twilight fades. Look far to its upper left for Altair, and far to its upper right for Saturn.


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.

Pocket Sky Atlas, jumbo edition

The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6 — which may sound like a lot, but it's less than one per square degree on the sky. Also plotted are many hundreds of telescopic galaxies, star clusters, and nebulae. Shown above is the Jumbo Edition for easier reading in the night. Larger view. Sample chart.

Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of charts). The basic standard is the Pocket Sky Atlas (in either the original or Jumbo Edition), which shows stars to magnitude 7.6.

Next up is the larger and deeper Sky Atlas 2000.0, plotting stars to magnitude 8.5; nearly three times as many. The next up, once you know your way around, is the even larger Uranometria 2000.0 (stars to magnitude 9.75). And read how to use sky charts with a telescope.

You'll also want a good deep-sky guidebook, such as Sue French's Deep-Sky Wonders collection (which includes its own charts), Sky Atlas 2000.0 Companion by Strong and Sinnott, or the bigger Night Sky Observer's Guide by Kepple and Sanner.

Can a computerized telescope replace charts? Not for beginners, I don't think, and not on mounts and tripods that are less than top-quality mechanically (meaning heavy and expensive). And as Terence Dickinson and Alan Dyer say in their Backyard Astronomer's Guide, "A full appreciation of the universe cannot come without developing the skills to find things in the sky and understanding how the sky works. This knowledge comes only by spending time under the stars with star maps in hand."

This Week's Planet Roundup

Saturn on June 11, 2017

This could be the sharpest image of Saturn ever taken from the ground. Damian Peach and six colleagues acquired it on June 11th using the 1-meter Pic Du Midi reflector high in the French Pyrenees. "Rarely seen details are observed, such as small ringlets within Ring C, including the Maxwell and Colombo divisions," writes Peach. "The Encke division is easily observed around the entire [outer] A ring." South is up.

Extremely high quality image of Jupiter by Damian Peach et al., June 11, 2017

And is this the best image of Jupiter ever taken from the ground? The same team at Pic du Midi took it the same night (June 11, 2017) — "months after opposition," notes Peach (as indicated by the slightly sideways illumination causing the shading on the left). North is up.

Mercury and Mars are deep down in the glow of sunset.

Venus (magnitude –4.2) shines brightly in the east before and during dawn.

Jupiter (magnitude –2.0, in Virgo) shines brightly in the southwest during evening. Spica (magnitude +1.0) glitters 10° left of it. In a telescope, Jupiter has shrunk to 37 arcseconds wide.

NASA's Juno spacecraft will fly over Jupiter's Great Red Spot on July 10th at a distance of only 9,000 kilometers. This flyby ought to provide the most detailed imagery of the Red Spot ever. Here's some recent infrared imagery of Jupiter in support of the mission. Update: And more.

Saturn (magnitude +0.1, in southern Ophiuchus) glows pale yellowish in the south-southeast to south during evening. Fiery Antares, less bright, is 14° to Saturn's right or lower right. Delta Scorpii, the third brightest object in the area, catches the eye half that far to the upper right of Antares.

Uranus (magnitude 5.9, in Pisces) and Neptune (magnitude 7.9, in Aquarius) are well placed in the east and southeast, respectively, before the beginning of dawn. Finder charts.


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, 2014

"Objective reality exists. Facts are often determinable. Vaccines stop diseases. Carbon dioxide warms the globe. Bacteria evolve in response to antibiotics. Science and reason are no political conspiracy; they are how we discover reality. Civilization's survival depends on our ability, and willingness, to do so."
— Alan MacRobert, your Sky at a Glance editor

"Facts are stubborn things; and whatever may be our wishes, our inclinations, or the dictates of our passions, they cannot alter the state of facts and evidence."
— John Adams, 1770


One thought on “This Week’s Sky at a Glance, June 30 – July 8

  1. Tony

    On the evening of July 2 at 9:50 PDT, I spotted Mercury with 16×50 binoculars while looking for Pollux. Mercury looked the brighter of the two by a healthy margin despite being lower in twilight. I’m on southern Vancouver Island at 48deg35min.

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