This Week's Sky at a Glance, October 6 – 15

FRIDAY, OCTOBER 6

■ Arcturus shines in the west as twilight fades away. Capella, equally bright, is rising in the north-northeast (depending on your latitude; the farther north you live the higher it will be.) They're both magnitude 0.

Later in the evening around 8 or 9, Arcturus and Capella shine at the same height. When will this happen? That depends on both your latitude and longitude.

When it does, turn around and look low in the south-southeast. There's 1st-magnitude Fomalhaut at about the same height — exactly so if you're at latitude 43° north (Boston, Buffalo, Milwaukee, Boise, Eugene). Seen from south of that latitude, Fomalhaut will appear higher than Capella and Arcturus are. Seen from north of there, it will be lower.

That bright light more than a third of the way from Capella to Fomalhaut is Jupiter.

Higher above Fomalhaut glows Saturn, pale yellow and steady.

■ Up really late tonight? The Moon, just past last quarter, rises around midnight (depending on your location). Once it's well up in the early morning hours of the 7th, you'll see that it's keeping company with Castor and Pollux, the heads of the Gemini twins, as shown below.

SATURDAY, OCTOBER 7

■ The Great Square of Pegasus balances on its corner high in the east at nightfall. For your location, when will it be exactly balanced? That is, when will the Square's top corner be exactly above its bottom corner? This will be sometime in the evening depending on your latitude and longitude. Try lining up the stars with the vertical edge of a building as a measuring tool. The tilt of the line changes very slowly.

SUNDAY, OCTOBER 8

■ Cygnus the Swan, with Deneb as its tail, floats straight overhead after nightfall. Its brightest stars form the big Northern Cross. When you face southwest and crane your head up, the cross appears to stand upright. It's about two fists at arm's length tall, with Deneb as its top. Or to put it another way, when you face that direction the Swan appears to be diving straight down.

MONDAY, OCTOBER 9

■ Set your alarm for about 1¼ or 1½ hours before your sunrise time on Tuesday morning the 10th, and you can catch Venus, the "Morning Star," hanging with the Moon. They're the two brightest celestial objects after the Sun. Much fainter is Regulus between them, as shown below.

The Moon and Venus will be 5° apart, meaning the trio will fit into the field of view of most binoculars.

TUESDAY, OCTOBER 10

■ After dark, Vega is the brightest star very high west of the zenith after dark. Face west and look up at it. To Vega's lower right by 14° (nearly a fist and a half at arm's length) is Eltanin, the nose of Draco the Dragon. The rest of Draco's fainter, lozenge-shaped head is a little farther behind. Draco always eyes Vega as they wheel around the sky.

The main stars of Vega's own constellation, Lyra — also pretty faint — extend 7° from Vega on the side opposite Draco's head.

Farther on in the same direction, you'll see that Lyra's pattern points to Altair.

■ In early dawn Wednesday morning, the waning Moon shines lower left of Venus and Regulus as shown above.

WEDNESDAY, OCTOBER 11

■ This is the time of year when, after nightfall, W-shaped Cassiopeia stands on end halfway up the northeastern sky — and when, off to its left in the north, the dim Little Dipper extends left from Polaris.

THURSDAY, OCTOBER 12

■ After dark, spot the W of Cassiopeia high in the northeast. It's standing almost on end. The third segment of the W, counting down from the top, points down. Extend that segment twice as far down as its own length, and you're at the Double Cluster in Perseus. This combined pair of little gray glows is dimly apparent to the unaided eye in a dark sky (use averted vision), and it's visible from almost anywhere with binoculars. It's two lovely star-spangles in a telescope.

FRIDAY, OCTOBER 13

■ Vega is the brightest star high in the west these evenings. Less high in the southwest is Altair, not quite as bright. Just upper right of Altair, by a finger-width at arm's length, is little orange Tarazed. Down from Tarazed runs the stick-figure backbone of the constellation Aquila, the Eagle, along the Milky Way.

SATURDAY, OCTOBER 14

■ Annular eclipse of the Sun today. The path of annularity crosses Oregon, northern Nevada, Utah, New Mexico, west-central and southern Texas, Central America, Colombia, and Brazil.

Meanwhile, a partial solar eclipse will be seen over a much wider area: practically all of North, Central, and South America and the Caribbean.

Maps. Timetable for places in the path of annularity. Timetable for the partial eclipse in the US. In Canada. More about this event is in the October Sky & Telescope starting on page 34. Plan your eclipse-sequence photography starting on page 60.

Online are Fred Espenak with Observing October's Annular Eclipse and Jay Anderson on how to chase clear skies as the final days count down: DIY Weather Forecast for the October 14th Eclipse.

■ New Moon — because, of course, it's solar eclipse day! The exact time of new Moon is listed in almanacs as 1:55 p.m. EDT. This time refers (as always) to a hypothetical observer at the center of the Earth.

SUNDAY, OCTOBER 15

■ Now that it's mid-October, Deneb has replaced Vega as the zenith star after nightfall (for skywatchers at mid-northern latitudes). Accordingly, Capricornus has replaced Sagittarius as the zodiacal constellation low in the south.

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This Week's Planet Roundup

Mercury is out of sight low in the glow of sunrise.

Venus, brilliant at magnitude –4.6 in Leo, is as high as it's going to get as the "Morning Star." Look east before and during dawn. Venus rises more than two hours before dawn's first light — a weird UFO on the eastern horizon.

Watch Regulus, only 1 percent as bright, pass Venus this week. It moves day by day from Venus's lower left to upper right. They appear closest, 2.3° apart, on the morning of October 9th.

In a telescope, Venus is a very thick "crescent" almost at dichotomy (half-lit phase).

Mars is out of sight behind the glare of the Sun.

Jupiter (magnitude –2.8, in Aries) rises in the east-northeast in late twilight. Jupiter dominates the eastern sky later in the evening and shines highest in the south during the early-morning hours. It's on its way to opposition November 2nd.

Saturn (magnitude +0.6, in dim Aquarius) is the brightest "star" in the southeast in twilight. It shines at a good height for telescopic viewing as early as 8 p.m. now and is highest in the south around 10.

Fomalhaut twinkles two fists at arm's length below it, and Altair shines about four fists to Saturn's upper right.

Uranus, magnitude 5.6 in Aries, is 9° east of Jupiter.

Neptune, magnitude 7.8 at the Aquarius-Pisces border, is nice and high by mid-evening 25° east of Saturn.

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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. The next up, once you know your way around, are the even larger Interstellarum atlas (stars to magnitude 9.5) or Uranometria 2000.0 (stars to mag 9.75). And be sure to 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.

Do computerized telescopes replace charts? Not for beginners I don't think, especially not 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 getting to know 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."

But finding faint objects the old-fashioned way with charts isn't simple either. Learn the 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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