This Week’s Sky at a Glance, July 25 – August 2

Sharp view of Saturn, June 1, 2014

Christopher Go took this extraordinarily sharp image of Saturn during excellent seeing on June 1st using a 14-inch scope. It's a stack of many selected video frames, de-rotated and expertly processed. South is up. Note the growing shadow of the globe on the rings (just off the globe's lower-right edge), and the shadow of the rings on the globe (just above the rings' edge at top).

Friday, July 25

Mars and Spica shine in the southwest at nightfall. Mars keeps pulling farther away from Spica; they're now 6° apart. Saturn glows pale yellow to their upper left. Arcturus sparkles high to their upper right.

Saturday, July 26

New Moon (exact at 6:42 p.m. EDT).

Summer is hardly more than a third over, astronomically speaking. But already the Great Square of Pegasus, symbol of the coming fall, heaves up from behind the east-northeast horizon at dusk and climbs higher in the east through the evening. It's balancing on one corner.

Sunday, July 27

Quick, can you name the star cluster just off the handle of the Teaspoon in Sagittarius? If you said NGC 6774, you quality for a tiny inner sanctum of the sky elite. And yet it's visible in binoculars — Gary Seronik calls it "an easy catch in my 10×30 image-stabilized binos." See his Binocular Highlight column and chart for this V-shaped object in the August Sky & Telescope, page 45.

Monday, July 28

Mars continues its eastward trek against the cosmic backdrop. Look southwest at dusk. You'll notice that it's now definitely closer to Saturn than Antares is. Mars is to Saturn's lower right; Antares is to Saturn's lower left.

Tuesday, July 29

Vega is the brightest star very high in the east. Far down to its lower right shines Altair, almost as bright. Altair is flagged by little Tarazed (3rd magnitude) a finger-width above it, an orange giant far in Altair's background.

Wednesday, July 30

The two brightest stars of summer are Vega, just east of the zenith after dark, and Arcturus, less high toward the west. Both are zero magnitude.

The next zero-magnitude star to make its appearance will be Capella. It doesn't emerge until the early-morning hours. Look for it low in the north-northeast after about 1 a.m. local time (depending on your location, especially your latitude).

Thursday, July 31

In a really dark sky, the Milky Way now forms a magnificent arch high across the whole eastern sky after darkness is complete. It runs all the way from below Cassiopeia in the north-northeast, up and across Cygnus and the Summer Triangle high in the east, and down past the spout of the Sagittarius Teapot in the south.

Evening Moon passing Spica, Mars, and Saturn

Watch from night to night as the waxing Moon moves eastward past the lineup of Spica, Mars, and then Saturn. (The blue 10° scale is about the size of your fist held at arm's length. The Moon is plotted for the middle of North America, and it's shown three times actual apparent size.)

Friday, August 1

At dusk this evening, the Moon forms the lower-right end of a very long, curving line of celestial objects. Counting to the Moon's upper left, these are Spica, Mars, and Saturn, as shown here.

Today is Lammas Day or Lughnasadh, one of the four traditional "cross-quarter" days midway between the solstices and equinoxes. More or less. The actual midpoint between the June solstice and the September equinox this year comes at 2:40 a.m. August 7th Eastern Daylight Time (6:40 UT). That will be the exact midpoint of astronomical summer.

Saturday, August 2

The Moon shines about midway between Spica and Mars this evening, as shown here. Tomorrow evening it'll be between Mars and 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. Or download our free Getting Started in Astronomy booklet (which only has bimonthly maps).

Pocket Sky Atlas

The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6 — which may sound like a lot, but it's still less than one per square degree on the sky. Also plotted are many hundreds of telescopic galaxies, star clusters, and nebulae.

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 (able to point with better than 0.2° repeatability, which means fairly 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 (about magnitude –0.3) is sinking away deep into the glow of sunrise this week, farther and farther to the lower left of Venus.

Venus (magnitude –3.8) shines low in the east-northeast during dawn, far below Capella.

Mars (magnitude +0.4, in Virgo) is in the southwest at dusk. Spica twinkles to its lower right. In a telescope Mars's tiny gibbous disk is only 8 arcseconds tall.

Jupiter is very deep in the glare of sunrise.

Saturn (magnitude +0.5, in Libra) shines in the south-southwest in twilight, to the upper left of the Mars-Spica pair.

Uranus, in Pisces, and Neptune, in Aquarius, are nicely high in the southeast and south well before the first light of dawn. Use our finder charts for Uranus and Neptune.

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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.


 

One thought on “This Week’s Sky at a Glance, July 25 – August 2

  1. mary bethmary beth

    Last night, I noticed that the angle formed from Spica to the Cat’s Eyes looked like a housetop! Nice expanse of my favorite objects! I enjoyed reading about Pegasus. I highly encourage readers to download the S&T app. I love the feature that allows you to change date and time down to a second! I am interested in helical risings and this feature makes it fun! Thank you staff at S&T!

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