This Week's Sky at a Glance, August 9 – 18

FRIDAY, AUGUST 9

■ Early this evening, look west-southwest to spot Spica just 4° or 5° upper left of the crescent Moon.

Very high above or upper right of them shines Arcturus, brighter and pale yellow-orangish.

■ Before and during early dawn Saturday morning, take a look high in the east to catch Jupiter and Mars closing in on each other as shown below. They'll pass each other on Wednesday morning the 14th.

SATURDAY, AUGUST 10

■ This evening Spica shines to the Moon's right or lower right as twilight fades out. It's a little farther from the Moon than it was yesterday evening (as seen from the Americas).

■ The two brightest stars of summer are Vega, overhead shortly after nightfall, and Arcturus, shining in the west. Draw a line down from Vega to Arcturus. A third of the way down, the line crosses the dim Keystone of Hercules. Two thirds of the way down to Arcturus the line crosses the dim semicircle of Corona Borealis with its one modestly bright star, Alphecca. Near which, T Coronae Borealis may explode at any time.

■ Vega and the Hercules Keystone star closest to it (higher than the field above) form an equilateral triangle with 2nd-magnitude Eltanin to their north, the nose of Draco the Dragon. Eltanin is the brightest star of Draco's quadrilateral head. He's eyeing Vega.

SUNDAY, AUGUST 11

■ It's peak Perseid meteor night! And maybe the first of two. The actual peak of the shower is supposed to be from about 13h to 16h UT on the 12th, which is 9 a.m. to noon on the 12th Eastern Daylight Time; 6 to 9 a.m. Pacific Daylight time. That's not long after the ideal Perseid meteor-watching hours before dawn. But who knows, the next night could be just as good or nearly so.

In early evening the meteors will be few, but those that do appear will be Earth-grazers skimming far across the top of the atmosphere. As the hours pass and the shower's radiant (in northern Perseus near Cassiopeia) rises higher in the northeast, the meteors will become shorter and more numerous. The first-quarter Moon sets around 11 p.m. daylight-saving time, leaving the sky nicely dark. The shower's radiant continues to gain altitude until dawn puts an end to the show.

Layer up warmly even if the day was hot; remember about radiational cooling late at night under an open clear sky! A sleeping bag makes good mosquito armor, and use DEET on whatever parts of you remain exposed.

Bring a reclining lawn chair to a dark, open spot where no local lights get in your eyes. Lie back, and gaze up into the stars. Be patient. As your eyes adapt to the dark, you may see a meteor every minute or so on average as night grows late. You'll see fewer under light pollution, but the brightest ones will shine through.

The best direction to watch is where your sky is darkest, usually overhead. The shower's radiant (the meteors' perspective point of origin, if you could see them coming from the far distance) is in northern Perseus under Cassiopeia. But the meteors only become visible when they hit the upper atmosphere, and this can occur anywhere in your sky.

For more see Bob King's Woo-hoo — The Perseid Meteor Shower Is Coming!

MONDAY, AUGUST 12

■ The waxing Moon shines in the southwest after dusk. Look for orange Antares a little more than a fist at arm's length to the Moon's left or upper left. About halfway between them is Pi Scorpii, 3rd magnitude, the bottom star of the vertical row of three forming Scorpius's flat head.

■ Will the Perseids be as active late tonight as they were late last night? Set up again to watch and find out! See yesterday. Tonight the first-quarter Moon sets around 11 or midnight daylight saving time, depending on your location.

TUESDAY, AUGUST 13

■ Now the gibbous Moon shines only a degree or two from Antares. Cover the bright Moon with your fingertip to see its surrounding stars more easily.

■ Jupiter and Mars shine together in conjunction in the early morning hours tonight (Wednesday morning the 14th). They'll be just 0.3° apart. That's the width of the thin end of a chopstick held at arm's length. The two planets will easily fit into the same telescopic field of view at less than 100 power. Jupiter will be a white ball 37 arcseconds wide, perhaps showing its major belts (pale tan). Mars will be a much littler yellow-orange blob just 6 arcseconds wide.

WEDNESDAY, AUGUST 14

■ Now the gibbous Moon shines between Antares to its right and the Sagittarius Teapot to its left.

THURSDAY, AUGUST 15

■ This evening the Moon is in the Teapot, by its spout (for evening in North America). Again, cover the Moon with your fingertip to better see its background stars.

FRIDAY, AUGUST 16

■ The Moon is just left of the Teapot's handle this evening.

SATURDAY, AUGUST 17

■ As summer progresses and Arcturus moves down the western evening sky, the kite figure of Boötes that sprouts up from Arcturus tilts to the right (depending on your latitude). The kite is narrow, slightly bent, and 23° long: about two fists at arm's length. Arcturus is the kite's bottom point where the stubby tail is tied on.

■ The Big Dipper now slants at about the same height in the northwest, to the Kite's right. We're in the time of year when the Big Dipper scoops down during evening, as if to pick up the water that it will dump from high overhead early next spring.

SUNDAY, AUGUST 18

■ Whenever bright Vega shines nearest your zenith, as it does right after dark now, you know that the Sagittarius Teapot is at its highest down in the south.

Two hours later when Deneb passes the zenith, it's the turn of little Delphinus and boat-shaped Capricornus down below it to stand at their highest due south.

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This Week's Planet Roundup

Mercury is out of sight in conjunction with the Sun.

Venus, magnitude –3.8, is getting very slightly more visible week by week, very low above the west horizon in bright twilight. Look for it with binoculars a little to the right of due west starting 15 or 20 minutes after sunset. Much will depend on the clarity of your air; humid means hazy.

Mars and Jupiter (magnitudes +0.8 and –2.2, respectively, in Taurus) pair up closely this week. Watch for them to rise in the east-northeast around 1 a.m. daylight-saving time. Mars-like Aldebaran watches on from less than a fist at arm's length to their right. Above Aldebaran glitter the delicate Pleiades.

By the first sign of dawn they're all high in the east, with Orion below them, as shown at the top of this page.

The two planets rearrange daily. Mars shines to Jupiter's upper right early in the week, closing in on it day by day. On the morning of August 10th the planets are still 2° apart. They close to 0.3° apart on the morning of the 14th, the morning closest to their time of conjunction (17h UT) for observers in the Americas.

By next Saturday morning the 17th they're again 1.4° apart, now with Mars to Jupiter's lower left.

Saturn (magnitude +0.7, south of the Circlet of Pisces) rises in the east before the end of twilight. Saturn is lower right of the Great Square of Pegasus. The Square is balancing on one corner. Its top-right edge points diagonally down roughly toward Saturn two fists at arm's length away.

Saturn shines high toward the south, meaning through less blurry atmosphere for telescopic viewing, during the early-morning hours.

Uranus (magnitude 5.7, in western Taurus) is some 20° upper right of Mars and Jupiter in the early morning hours. You'll need a good finder chart to identify it among surrounding faint stars.

Neptune (a tougher magnitude 7.8, near the Circlet of Pisces) is 12° east of Saturn. Again you'll need a proper finder chart.

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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 and graphics that also depend on longitude (mainly Moon positions) are for North America.

Eastern Daylight Time (EDT) is Universal Time minus 4 hours. UT is also known as UTC, GMT, or Z time.

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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 a more detailed constellation guide covering the whole evening sky, use the big monthly map in the center of each issue of Sky & Telescope, the essential magazine of astronomy.

Once you get a telescope, to put it to good use you'll need a much more 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 all 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. (It's currently out of print.) The next up are the even larger Interstellarum atlas (stars to magnitude 9.5) or Uranometria 2000.0 (stars to mag 9.75). And read How to Use a Star Chart with a Telescope. It applies just as much to charts on your phone or tablet as to charts on paper.

You'll also want a good deep-sky guidebook. A beloved old classic is the three-volume Burnham's Celestial Handbook. An impressive more modern one is the big Night Sky Observer's Guide set (2+ volumes) by Kepple and Sanner. The top of the hill for total astro-geeks is the Annals of the Deep Sky series, currently at 10 volumes as it slowly works forward through the constellations alphabetically. So far it's only up to F.

Can computerized telescopes replace charts? Not for beginners I don't think, and not for scopes on mounts and tripods that are less than top-quality mechanically. Unless, that is, you prefer spending your time getting finicky technology to work rather than learning the sky. 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 and a curious mind." Without these, "the sky never becomes a friendly place."

If you do get a computerized scope, make sure its drives can be disengaged so you can swing it around and point it readily by hand when you want to, rather than only slowly by the electric motors (which eat batteries).

However, finding faint telescopic objects the old-fashioned way with charts isn't simple either. Learn the essential tricks at How to Use a Star Chart with a Telescope.

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Audio sky tour. Out under the evening sky with your
earbuds in place, listen to Kelly Beatty's monthly
podcast tour of the naked-eye heavens above. It's free.

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"The dangers of not thinking clearly are much greater now than ever before. It's not that there's something new in our way of thinking, it's that credulous and confused thinking can be much more lethal in ways it was never before."
            — Carl Sagan, 1996

"Facts are stubborn things."
            — John Adams, 1770

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