This Week’s Sky at a Glance, January 9 – 17

Some daily sky sights among the ever-changing Moon, planets, and stars.

Comet Lovejoy imaged on December 30th by Alan Tough in Australia.

Comet Lovejoy as imaged on December 30th by Alan Tough using a 4-inch f/5 refractor..

Comet Lovejoy is at its best this week and next, especially now that the Moon is gone from the evening sky. The comet is glowing at about 4th magnitude well to the west of Orion early in the week — nice in binoculars and possibly visible very dimly to the unaided eye, depending on your sky conditions. By week's end it's higher overhead, nearly west of the Pleiades. See our article and finder chart: How to See Comet Lovejoy.

Friday, January 9

In this coldest time of the year, the dim Little Dipper hangs straight down from Polaris after dinnertime — as if (per Leslie Peltier) from a nail on the cold north wall of the sky.

The Big Dipper, meanwhile, is creeping up low in the north-northeast, with its handle very low and its bowl to the upper right.

Mercury and Venus at their closest together, Jan.10, 2015

Catch Mercury and Venus shining closest together as twilight fades on Saturday evening the 10th. Little Mars looks on from their upper left.

Venus and Mercury in twilight Jan. 17, 2015

By Saturday the 17th, Mercury is pulling away to Venus's right.

Saturday, January 10

Venus and Mercury are closest together this evening in twilight, 0.7° apart. Look low in the southwest about 45 minutes after sunset, as shown here. They'll stay within 1° of each other through Monday.

Sunday, January 11

Early on these cold, cold evenings with the Moon now gone, bundle up for a telescopic adventure challenge in the hot southern constellation of Fornax, the Furnace, crossing the meridian low in the south. Sue French guides you through its galaxy riches with her Deep-Sky Wonders article, charts, and drawings in the January Sky & Telescope, page 56.

Monday, January 12

Here it is the coldest very bottom of the year, and the Summer Star, Vega, is still hanging in there. Look for it twinkling over the northwest horizon during and shortly after nightfall. The farther north you are the higher it will be.

As Vega sinks low, the Northern Cross stands upright on the horizon to its left.

Tuesday, January 13

In early evening at this time of year, the Great Square of Pegasus balances on one corner high in the west. The vast Andromeda-Pegasus constellation complex runs all the way from near the zenith (Andromeda's foot) down through the Great Square (Pegasus's body) to low in the west (Pegasus's nose, Enif).

Wednesday, January 14

Mercury is pulling away to the right of Venus now in twilight. Look low in the southwest. This evening they're still only 1.3° apart: roughly a finger's width at arm's length.

Thursday, January 15

Jupiter's moon Io fades into eclipse by Jupiter's shadow tonight around 12:27 a.m. Friday morning EST; 9:27 p.m. Thursday evening PST. Use a telescope to watch it dwindle out of view just to Jupiter's west. Around 10:56 p.m. EST, Jupiter's Great Red Spot crosses the planet's central meridian (north-south midline). For the whole month's schedule of events, good worldwide, see "Action at Jupiter" in the January Sky & Telescope, page 53.

Moon and Saturn at dawn, Jan. 16, 2015

The waning crescent Moon shines with Saturn at dawn on the 16th. (The Moon is positioned for a viewer in the middle of North America. The Moon in these scenes is always drawn three times its actual size).

Before dawn on Friday the 16th, look southeast for the waning Moon near Saturn. Below them twinkles Antares, as shown here.

Friday, January 16

Bright Capella high overhead, and bright Rigel in Orion's foot, are at almost the same right ascension — so they cross your sky’s meridian at almost the same time (around 9:30 p.m. now, depending on how far east or west you live in your time zone). This means that whenever Capella passes its very highest, Rigel marks true south over your landscape.

Capella goes exactly through your zenith if you're at latitude 46° north: for instance Portland, Oregon; Montreal; central France; Tokyo.

Saturday, January 17

This evening Comet Lovejoy is 8° west-southwest of the Pleiades, high overhead after dark. Think wide-field photo opportunity!

Sirius twinkles brightly after dinnertime below Orion in the southeast. Around 8 or 9 p.m., depending on your location, Sirius shines precisely below fiery Betelgeuse in Orion's shoulder. How accurately can you time this event for your location, perhaps using a plumb bob or the edge of a building? Sirius leads Betelgeuse early in the evening; Betelgeuse leads later. Welcome to pre-telescopic astronomy.


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 having a close pairing with Venus; look for them in low the southwest in the afterglow of sunset. Mercury is about magnitude –0.8; Venus shines 17 times brighter than that at magnitude –3.9. They shine closest together, 0.7° apart, on Saturday the 10th. They remain within 1° of each other through the 12th. By Friday the 16th Mercury is 2.2° to Venus's right or lower right. The farther south you live, the higher they'll be.

Mars (magnitude +1.2, between Capricornus and Aquarius) glows in the southwest at dusk upper left of Venus and Mercury. Mars continues to set around 8 p.m.

Jupiter on Dec. 27, 2014

Jupiter's Great Red Spot had just come around into view when S&T's Sean Walker took this image at 5:48 December 27th UT, using a 12.5-inch reflector. South is upper left. On the central meridian in the south is dark-rimmed Oval BA, called Red Spot Junior, "paler than in previous years" he notes. The northern side of the bright Equatorial Zone sports prominent bluish festoons.

Jupiter (magnitude –2.5, in western Leo) rises in the east-northeast around 7 p.m. About 50 minutes later, fainter Regulus (magnitude +1.4) rises below it. By dawn they're way over in the west — with Regulus now to Jupiter's upper left.

Saturn (magnitude +0.5, at the head of Scorpius) glows in the southeast before and during dawn. Look below it (by 10°) for twinklier Antares.

Uranus (magnitude 5.8, in Pisces) is still up in the southwest after dusk.

Neptune (magnitude 7.9, in Aquarius) is in the background of Mars, sinking low in the southwest just after dark.

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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 Standard Time (EST) is Universal Time (UT, UTC, or GMT) minus 5 hours.


"I do not know what I may appear to the world; but to myself I seem to have been only like a boy playing on the seashore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me."

— Isaac Newton, 1642–1727

(From the Memoirs of the Life, Writings, and Discoveries of Sir Isaac Newton, David Brewster, 1855)