This Week’s Sky at a Glance, August 22 – 30

Friday, August 22

Altair is the brightest star shining halfway up the southeastern sky after nightfall. Look to its left, by a little more than a fist at arm's length, for the dim but distinctive constellation Delphinus, the Dolphin. He's leaping leftward, just below the Milky Way.

Moon, Venus, and Jupiter form a triangle at dawn August 23, 2014

The waning Moon passes Jupiter and Venus low in the east as dawn brightens. (The Moon here is positioned for the middle of North America. European skywatchers should move each Moon symbol a quarter of the way toward the one for the previous date.)

In Saturday's dawn, the thin waning crescent Moon forms an elegant triangle with Jupiter and Venus low in the east, as shown at lower right.

Saturday, August 23

August is prime Milky Way time. After dark, the Milky Way runs from Sagittarius and Scorpius in the south-southwest, up and left across Aquila and through the big Summer Triangle very high in the southeast and east, and on down through Cassiopeia to Perseus rising low in the north-northeast.

Sunday, August 24

Mars and Saturn are closest together this evening and Monday evening, separated by 3.4°. They're the same brightness but not the same color. And compare Mars's color to that of its rival Antares, not quite as bright, in Scorpius about 20° to the left. (See the last illustration below.) Mars will pass Antares by just 3° in late September.

Monday, August 25

Before moonlight comes back into the evening sky, take the opportunity to explore the dim nebulae, and the somewhat brighter star clusters, around Deneb and the North America Nebula in Cygnus, now nearly overhead. They're not easy; use Sue French's maps, drawing, photo, and article in the September Sky & Telescope, page 56, to pinpoint what you're looking for.

New Moon (exact at 10:13 a.m. EDT).

Tuesday, August 26

If you're in the Earth's mid-northern latitudes, bright Vega shines near your zenith just as night becomes fully dark. Whenever you see Vega most nearly straight up, you know that Sagittarius, with its deep-sky riches, is at its highest in the south.

Wednesday, August 27

The wide W pattern of Cassiopeia is tilting up in the northeast after dark. Below the W's last segment to the lower left, by a little farther than the segment's length, look for an enhanced spot of the Milky Way's glow if you have a dark enough sky. Binoculars will show this to be the Perseus Double Cluster — even through a fair amount of light pollution.

Thursday, August 28

The Great Square of Pegasus is now well up in the east as soon as nightfall is complete. It's larger than your fist at arm's length and currently stands on one corner. Seen from your latitude at your time, how close is the balance to perfect?

Friday, August 29

The Moon is coming back into the evening sky. Look for the waxing crescent low in the southwest in twilight, as shown below. Can you make out Spica twinkling beneath it? Binoculars help. Far to the upper left are Saturn and Mars.

The waxing Moon crosses the southern sky as seen at dusk each evening, passing Saturn and Mars.

The waxing Moon steps to the east (left) as seen at dusk each evening, passing Saturn and Mars.

Saturday, August 30

The waxing crescent Moon now shines closer to Saturn and Mars, as shown here. Can you see little Alpha Librae inside the middle of the narrow triangle they make?


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 is deep in the sunset.

Venus (magnitude –3.9) and Jupiter (a sixth as bright at magnitude –1.8) shine low in the east-northeast during dawn. Jupiter is the upper one. They're drawing farther apart each morning: from 5° apart on August 23rd to 12° by the 30th. Jupiter is moving higher, and Venus is gradually sinking a little lower.

Mars and Saturn at dusk

Watch Mars passing leftward below Saturn day by day at dusk.

Mars and Saturn, both magnitude +0.6, glow in the southwest at dusk, finally having their conjunction. Mars is the lower one. They'll be just 3½° apart from August 23rd to 26th, then will widen again slowly. Compare their colors.

In a telescope, Mars is just a tiny 7 arcseconds wide. Saturn's dimmer globe is 17 arcseconds wide, and its rings span 38 arcseconds from end to end.

The fainter star just to their right is the wide binocular double Alpha Librae, magnitudes 2.8 and 5.2.

Uranus (magnitude 5.8 in Pisces) and Neptune (magnitude 7.8 in Aquarius) are well placed in the southeast and south after midnight. See our Finder charts for Uranus and Neptune online or in the September Sky & Telescope, page 50.


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.


"The universe is full of magical things patiently waiting for our wits to grow sharper."

— Eden Phillpotts, "A Shadow Passes," 1918


 

6 thoughts on “This Week’s Sky at a Glance, August 22 – 30

  1. mary bethmary beth

    I’m really looking forward to comparing the colors of the planets, and also just seeing them so close together! The crescent moon will be an enchanting addition to the sky as well. Its pairing with the departing Spica will be a very picturesque way to end the summer! Hope all S&T readers have clear skies and enjoy the last weeks of the Late Summer night sky!

    The moving Moon went up the sky,
    And nowhere did abide;
    Softly she was going up,
    And a star or two beside.

    –Samuel Taylor Coleridge (1772–1834)

  2. David DunnDavid Dunn

    It will be good to look at Saturn and Mars in the evening, even if they doing get that close. I’ll be able to tell my students next week about it. Missed the Jupiter and Venus gathering, however.

  3. mary bethmary beth

    Hope the new school year gets off to a great start! Hard to believe its already that time of year! Your students will have lots of ‘homework’ this week :)! I missed the J/V gathering also….was too lazy to get up. M/S were so bright as they sank in the late evening sky. The color differences were very noticeable. I saw Zubenelgenubi pretty clearly on Thursday. Too bad your classes weren’t online, live!! I’d love to hear your lectures! Happy Stargazing!!

  4. Paul-Noble

    Did get up early to feed the horses on 9/20 and saw the close pairing of J/V with the moon nearby.
    If only Mercury was in the mix…..

    1. mary bethmary beth

      Nice! A very pastoral scene! Makes me wonder what the animals ‘see’ that we miss by sleeping. Glad you got to enjoy!

  5. mary bethmary beth

    I was pleasantly surprised to see the crescent moon last evening. We had clouds on the western horizon but I caught a glimpse of a dark orange spot, then clouds cleared and we saw a big slender young moon right before it set. My neighbor said it looked very autumny. Spica and Antatres seemed extra brilliant. The ISS had flown over right before dark as well, so it was a very busy night in the Houston sky!

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