This Week's Sky at a Glance, December 27 – January 5

FRIDAY, DECEMBER 27

■ Jupiter is nearly a month past its opposition. So it's already fairly high in the east when you first catch sight of it through the fading twilight.

How much later in twilight will you first see Aldebaran 6° to its right, twinkling pale orange? And then the 3rd and 4th-magnitude stars of the Hyades V, lying on its side?

■ As soon as nightfall is complete, spot brilliant Venus in the southwest. Look just 1° to its left, less than a finger-width at arm's length, for 3rd-magnitude Delta Capricorni. Binoculars will help. Although 3rd magnitude sounds easy naked-eye, Delta Cap is less than a thousandth as bright as Venus!

■ As dawn brightens tomorrow morning the 28th, look very low in the southeast for the thin waning crescent Moon. Antares is only about 1° to the Moon's left, while brighter Mercury is 8° to the Moon's left, as shown below. Binoculars help.

Antares is magnitude +1.1. Mercury is magnitude –0.3, almost four times brighter.

SATURDAY, DECEMBER 28

■ Now, right after dark, Delta Capricorni has moved to glimmer 1.2° below or lower left of Venus.

■ Unique lineup of Jupiter's satellites. If you're in the Eastern time zone, early this evening Jupiter's satellites will look seriously out of kilter. We're used to seeing them line up on either side of Jupiter in a more or less straight line with it, like they're all beads on a wire. But at 6:34 p.m. EST this evening, you can catch Callisto, Europa, and Io forming a very straight line that's canted way out of whack, aiming away from Jupiter entirely!

What's happening? Such things can occur because the plane of Jupiter's orbit is currently tipped slightly to our line of sight, allowing unusual perspectives to be presented to us. See Bob King's More Unusual Jovian Satellite Lineups.

SUNDAY, DECEMBER 29

■ As the year nears its end, Orion fully comes into his own. He's striding up the east-southeastern sky as soon as it gets dark, with his three-star Belt nearly vertical. Left of the Belt is orange Betelgeuse and right of the Belt is bright white Rigel, supergiants both.

The Belt points up toward Aldebaran and Jupiter and, even higher, the Pleiades. In the other direction, it points down to where Sirius rises less than an hour after twilight's end.

MONDAY, DECEMBER 30

■ The Pleiades cluster shines very high in the southeast after dinnertime, no bigger than your fingertip at arm's length. How many Pleiads can you count with your unaided eye? Take your time and keep looking. Most people with good or well-corrected vision count 6. With extra-sharp vision, a good dark sky, and a steady gaze, you may be able to make out 8 or 9. Binoculars will show dozens.

■ New Moon (exact at 5:27 p.m. EST).

TUESDAY, DECEMBER 31

■ After the noise and whoopla at the turning of midnight tonight, put down your drink (or whatever) and step outside into the silent, cold dark. Shining at its highest in the south will be Sirius. It is the bottom star of the bright, equilateral Winter Triangle. The other two are Betelgeuse in Orion's shoulder to Sirius's upper right, and Procyon the same distance to Sirius's upper left. The Triangle now stands upright, just about in balance on Sirius as the old year tips to the new.

And this year, upper right of Betelgeuse Jupiter shines brightly, and upper left of Procyon Mars shines brightly. They are extensions of the sides of the triangle. With it they form a giant, Hyades-shaped Taurus face, some 15 times larger than the original just under Jupiter. Gaze into that huge entity, and feel it looking back at you in its enormity. Keep looking; try to perceive what it is silently telling you. Therein lies an omen for the new year from your subconscious mind. You are free to accept it, or to refuse it and hurl it back in the giant Taurus face. Only one of those choices will be correct. Choose wisely. It will likely be the one whereby you move in the direction of greatest courage.

WEDNESDAY, JANUARY 1

■ Jupiter's moon Io slides behind Jupiter's western limb at 7:53 p.m. EST. Watch it reappear from eclipse out of Jupiter's shadow at 10:43 p.m. EST, a little east of the planet.

THURSDAY, JANUARY 2

■ To the right of bright Jupiter these evenings shines orange Aldebaran, which comes with the large, loose Hyades cluster in its background. Binoculars are the ideal instrument for this cluster given its size: its brightest stars (magnitude 3.5 to 5) span an area about 4° wide. Higher above, the Pleiades are hardly more than 1° across counting just the brightest stars.

The main Hyades stars form a V, lying on its side in the evening. Aldebaran forms the lower of the V's two tips. With binoculars, follow the lower branch of the V to the right from Aldebaran. The first thing you come to is the House asterism: a pattern of stars like a child's drawing of a house with a peaked roof. The house is currently upright and bent to the right like it got pushed.

The House includes three easy binocular double stars that form an equilateral triangle, with each pair facing the others. The brightest pair is Theta¹ and Theta² Tauri (the only members of the House that appear on the chart at the top of this page). You may find that you can resolve the Theta pair with your unaided eyes.

■ Action at Jupiter. Ganymede slowly reappears out from behind Jupiter's eastern limb at 7:00 p.m. EST, only to slowly disappear into Jupiter's shadow 26 minutes later. It re-emerges from the shadow farther out from Jupiter at 9:44 p.m. EST.

Meanwhile, Io slides off of Jupiter's western edge at 7:12 p.m., followed by its tiny black shadow leaving Jupiter's face at 7:52 p.m. EST.

And Jupiter's Great Red Spot, not exactly easy to see, should cross the planet's central meridian around 10:59 p.m. EST.

■ This will likely be a poor year for the Quadrantid meteor shower early Friday morning if you're in North America or Europe. The "Quads" have a brief, strong peak that lasts 6 hours or less, with little activity before and after. This year the peak should be centered near 17:45 UT January 3rd (1:45 p.m. EST) according to the International Meteor Organization. That would be good for the northwestern Pacific Ocean. Other sources give predictions as early 15:00 UT (10 a.m. EST, 7 a.m. PST), good for Alaska and possibly for the West Coast as the beginning of dawn approaches. There will be no moonlight.

The shower's radiant is in northernmost Boötes, between the end of the Big Dipper's handle and the head of Draco. It's highest before dawn.

FRIDAY, JANUARY 3

■ Crescent Moon and Venus. Once again the Moon, in its monthly orbit, shines near Venus in the west during and after dusk, as shown above. They'll be 3° apart at the end of twilight when seen from the East Coast, and 4° or 5° apart as seen from the West Coast. If you've missed previous such photo opportunities, here's a chance to try again.

■ And as Gary Seronik notes in the January Sky & Telescope, this afternoon the pairing presents a fine time to spot Venus in the daytime with your naked eyes. This can be surprisingly easy if you have sharp or well corrected vision. The trick is landing on Venus's exact location in the blue sky.

If you're in North America, "At about 3:30 p.m. local time the Moon is due south on the meridian," writes Seronik. "Once you've spotted the Moon, train your binoculars on it to get a sharp focus. Now, move the pale crescent to the left side of your field of view. Venus should pop into view near the right edge."

Now look at that spot without the binoculars. "If you have a very a transparent sky [i.e. deep blue], the planet is surprisingly easy to see" once your eyes land right on it. Keep trying.

SATURDAY, JANUARY 4

■ Now the thickening Moon shines upper left of Saturn, as shown above. For Iceland and much of Europe, the Moon occult Saturn.

SUNDAY, JANUARY 5

■ As we enter serious winter in January, the bowl of the Little Dipper hangs straight down from Polaris sometime around 8 or 9 p.m., as if (per Leslie Peltier) from a nail on the cold north wall of the sky.

The brightest star of the Little Dipper's dim bowl is Kochab, marking the bowl's lip. It's the equal of Polaris. Kochab passes precisely below Polaris around 8 p.m., depending on how far east or west you live in your time zone.

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This Week's Planet Roundup

Mercury, magnitude –0.4 for most of the week, is having one of its best dawn apparitions. Look for it low in the southeast about 60 minutes before sunrise.

Fainter Antares, magnitude +1.1, twinkles less than a fist at arm's length to Mercury's right on Saturday morning the 28th. That morning the thin waning Moon horns in on Antares, as indicated near the top of this page.

Each morning thereafter, Mercury gets a little lower and Antares climbs higher toward the upper right. A week later, on January 4th, they're separated by about a fist and a half.

Venus (magnitude –4.5, near the Capricornus-Aquarius border) shines high and bright as the "Evening Star" in the southwest during twilight. It's now high enough to remain up for some 2½ hours after dark before setting. It forms a big triangle with Saturn to its upper left and Fomalhaut more directly left or lower left.

Get your telescope on Venus early in twilight. This week it appears very close to half-lit, at "dichotomy."

Venus is enlarging as it swings toward us, catching up with us in its faster orbit. It now measures 22 arcseconds from pole to pole.

Mars (about magnitude –1.2, in Cancer) rises in the east-northeast around the end of twilight, below Castor and Pollux. Once it's high up, use binoculars to look for M44, the Beehive star cluster, 5° to 8° below it.

Mars shows best in a telescope when very high toward the southeast or south: by late evening or midnight. It has enlarged to about 14.2 arcseconds in apparent diameter — for all practical purposes, it's as large as it will appear (14.6 arcseconds) around its opposition January 15th.

A map of the major Martian surface features is in the January Sky & Telescope, page 48, in Bob King's article "Mars is in Fine Form." To find which side of Mars will be facing you at the time you'll observe, use our Mars Profiler tool.

See also Tom Dobbins's "The Shifting Sands of Mars" on page 52 of the January issue.

Jupiter, less than a month past its own opposition, shines at a bright magnitude –2.7 in Taurus. It dominates the high east to southeast during evening, with fainter orange Aldebaran to its right and the Pleiades higher above them. Jupiter is at its telescopic best once it's very high by 8 p.m. It's still 47 arcseconds wide.

Saturn, magnitude +1.0 in Aquarius, glows in the southwest after dark, upper left of Venus and closing in on it fast. Saturn is 21° from Venus on December 27th and 14° from it by January 3rd. Watch them continue to approach each other toward their conjunction on January 18th, when they will pass each other by 2.2°.

This week the two still form a big triangle with Venus and with Fomalhaut (the same brightness as Saturn) below Saturn. Watch the triangle change shape from night to night.

Uranus (magnitude 5.7, at the Taurus-Aries border) is very high in the southeast to south in the evening, 8° from the Pleiades. You'll need a good finder chart to tell it from the similar-looking surrounding stars. See the November Sky & Telescope, page 49.

Neptune (tougher at magnitude 7.9, under the Circlet of Pisces) is high in the south after dark, 13° east of Saturn. Again you'll need a sufficient 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 Standard Time (EST) is Universal Time minus 5 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. Both show all 30,000 stars to magnitude 7.6, and 1,500 deep-sky targets — star clusters, nebulae, and galaxies — to search out among them.

Next up is the larger and deeper Sky Atlas 2000.0, plotting stars to magnitude 8.5; nearly three times as many, as well as many more deep-sky objects. It's currently out of print, but maybe you can find one used.

The next up, once you know your way around well, are the even larger Interstellarum atlas (201,000+ stars to magnitude 9.5, and 14,000 deep-sky objects selected to be detectable by eye in large amateur telescopes), andUranometria 2000.0 (332,000 stars to mag 9.75, and 10,300 deep-sky objects). 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 pinnacle for total astro-geeks is the new Annals of the Deep Sky series, currently at 11 volumes as it works its way forward through the constellations alphabetically. So far it's up to H.

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 how to explore the sky. 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 that 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. Do 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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