This Week’s Sky at a Glance, July 3 – 11

Friday, July 3

Venus and Jupiter, low in the west at dusk, are now 1.5° apart: still strikingly close but widening every day.

Venus and Jupiter still make quite a sight. The blue 10° scale is about the size of your fist at arm's length.

Venus and Jupiter still make quite a sight. The blue 10° scale is about the size of your fist at arm's length.

Venus and Jupiter move wider apart (and lower) every day, as Regulus draws closer to them.

Venus and Jupiter move wider apart (and lower) every day, as Regulus draws closer to them.

Saturday, July 4

Out to watch fireworks? As dusk settles in, do a bit of astronomy outreach. Point out to people Venus and Jupiter still forming a striking pair low in the west (1.9° apart now). And fainter Regulus to their upper left.

Also the two brightest stars of summer: Arcturus, 37 light-years away, very high toward the southwest, and Vega, 25 light-years distant, nearly as high in the east. It's amazing the number of people who don't quite grasp you can see such things for yourself, with your own eyes.

Sunday, July 5

Vega is the brightest star high in the east. Barely to its lower left after dark is one of the best-known multiple stars in the sky: 4th-magnitude Epsilon (ε) Lyrae, the Double-Double. It forms one corner of a roughly equilateral triangle with Vega and Zeta (ζ) Lyrae. The triangle is less than 2° on a side, hardly the width of your thumb at arm's length. Binoculars easily resolve Epsilon, and a 4-inch telescope at 100× or more should resolve each of Epsilon's wide components into a tight pair.

Zeta Lyrae is also a double star for binoculars; much tougher, but easily split with any telescope. Delta (δ) Lyrae, a similar distance below Zeta, is much wider and easier to separate.

Monday, July 6

After nightfall, Altair shines in the east-southeast. It's the second-brightest star on the eastern side of the sky, after Vega high to its upper left. Above Altair by a finger-width at arm's length is little orange Tarazed. And a bit more than a fist-width to Altair's lower left is Delphinus, the Dolphin, leaping leftward.

Tuesday, July 7

The Big Dipper, high in the northwest after dark, is turning around to "scoop up water" through the evenings of summer and early fall.

Wednesday, July 8

Last-quarter Moon (exact at 4:24 p.m. EDT). It rises around 1 a.m. tonight, in Pisces far below the Great Square of Pegasus (and close below dim Uranus!).

Have you ever explored the Small Sagittarius Star Cloud, between M23 and M25? On these moonless late evenings, work through this area with Sue French's Deep-Sky Wonders story, chart, and photos in the July Sky & Telescope, page 56.

And stretch your observing skills with Rod Mollise's Deep-Sky Summer tour, page 62.

Got a big scope? Explore the galaxy cluster above the back of Draco with Ken Hewitt-White's Going Deep, page 59.

Thursday, July 9

This month two spacecraft are imaging the two brightest dwarf planets, Ceres and Pluto, up close. Find Ceres, magnitude 7.7, just below Capricornus using the chart in the July Sky & Telescope, page 50. Pluto is a daunting 14th magnitude, but its chart starts on page 52. Coincidentally, both are in the late-night southern sky about 25° apart.

The waning crescent Moon passes the "fall and winter" stars of Taurus in the dawns of July. Look early!

The waning crescent Moon passes the "fall and winter" stars of Taurus in the dawns of July. Look early! The Moon is plotted for its position at the time of twilight near the middle of North America: at latitude 40° north, longitude 90° west.

Friday, July 10

If you have a dark enough sky, the Milky Way now forms a magnificent arch high across the whole eastern sky after nightfall is complete. It runs all the way from below Cassiopeia in the north-northeast, up and across Cygnus and the Summer Triangle (crowned by bright Vega) in the east, and down past the spout of the Sagittarius Teapot in the south.

Saturday, July 11

As dawn brightens on Sunday morning the 12th, look east for the thin waning crescent Moon not far from Aldebaran, as shown here. Observers in Japan, northeast Siberia, and the far north of North America can see the Moon occult (cover) the orange-giant star. Far to Aldebaran's lower left (out of the scene here) is brighter Mercury.

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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.

Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of charts). The standards are the little Pocket Sky Atlas, which shows stars to magnitude 7.6; the larger and deeper Sky Atlas 2000.0 (stars to magnitude 8.5); and once you know your way around, 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, the bigger Night Sky Observer's Guide by Kepple and Sanner, or the beloved if dated Burnham's Celestial Handbook.

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). 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

Mercury is low in the glow of dawn, brightening from magnitude –0.4 to –1.0 this week. Look for it 30 or 40 minutes before sunrise just above the east-northeast horizon, very far down to the lower right of Capella. Binoculars help, especially as dawn grows bright. (Don't confuse Mercury with 1st-magnitude Aldebaran far to its upper right.)

On June 30th, Damian Peach imaged Venus at high resolution in the near-infrared shortly before sunset. "No details were seen."

Shortly before sunset on June 30th, Damian Peach imaged Venus at high resolution in the near-infrared. "No details were seen."

Venus and Jupiter are the two bright "stars" low in the west at dusk. They're moving apart after their June 30th conjunction and are getting lower every week. But they still make an impressive pair, shining at an magnitude –4.7 and –1.8, respectively. Jupiter is the one on the right. They're separated by 1.5° on July 3rd and 4.1° by the 10th. Look for fainter Regulus to their upper left.

Mars is hidden deep in the glare of sunrise.

Saturn (magnitude +0.3, in Libra upper right of the head of Scorpius) is highest in the south at dusk. Lower left of Saturn by 13° twinkles fiery orange Antares, not quite as bright. Delta Scorpii is the star roughly midway between them.

Uranus (magnitude +5.8, in Pisces) and Neptune (magnitude +7.9, in Aquarius) are in the southeast and south, respectively, just before dawn begins to brighten. Finder charts.

Jupiter map by Peach, March 2015

Damian Peach assembled this complete map of Jupiter from images he took in March 2015. Click here for full-size version. North is up. Among other notable features are Red Spot Junior (Oval BA) to the lower right of the Great Red Spot, eleven white ovals all at the same latitude just a bit farther south in the South Temperate Belt, and the strikingly dark red, but transient, barge in the broken North Temperate Belt. Here's a rotating Jupiter globe that Peach made from this map.

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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.

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“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

 


One thought on “This Week’s Sky at a Glance, July 3 – 11

  1. Jakob

    There is a slight error in the dusk picture of july 11. Venus should be the brighter object of the two planets. My very best regards from Sweden. Jakob

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