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

Friday, January 2

This evening the Moon shines among some of the sky's brightest relatively cool stars. Look for orange-red Aldebaran (spectral type K5 III) to the Moon's upper right, similarly tinted Betelgeuse (type M2 Iab) farther below the Moon, and orange Pollux (type K0 III) much farther to the Moon's lower left. Hotter Capella, yellow-white and type G5 III, shines high to the Moon's upper left.

Venus and Mercury at dusk, Jan. 3, 2015
Keep watch as Mercury edges up closer to Venus day by day this week and next.

Saturday, January 3

Are you tracking Venus and Mercury yet? They're just 2½° apart now, low in the afterglow of sunset in the southwest as shown here. Brilliant Venus is on top. They're drawing closer together and will appear closest, just 0.7° apart, a week from today.

Sunday, January 4

Tonight the eclipsing variable star Algol should be at minimum light, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 12:07 a.m. EST. Algol takes several additional hours to fade and to rebrighten.

Monday, January 5

The bright Moon forms a curving line this evening with Castor and Pollux to its upper left, and Procyon to its lower right.

Sirius and Procyon in the balance: From Procyon, look far to the right for brighter Sirius, the Dog Star, sparkling low in the east-southeast after dinnertime. If you live around latitude 30° north (Tijuana, New Orleans, Jacksonville), the two canine stars will be at the same height above your horizon soon after they rise. If you're north of that latitude, Procyon will be higher. If you're south of there, Sirius will be the higher one.

Moon and Jupiter, Jan. 6-8, 2014
Watch the Moon pass Jupiter and Regulus as it wanes away from full.

Tuesday, January 6

Watch lower left of the Moon for Jupiter and then Regulus to rise in early evening.

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) almost to the western horizon (Pegasus's nose).

Wednesday, January 7

This evening you can finally see Comet Lovejoy in a moonlight-free sky again — if you look within an hour or so after dark (for most of the world's mid-northern latitudes). The comet is closest to Earth tonight, and it's also entering its brightest two weeks at 5th or 4th magnitude. But you'll have to know exactly the correct point in the sky to examine! See our updated article with finder chart: How To See Comet Lovejoy Tonight.

The waning gibbous Moon rises about an hour after darkness is complete. Brilliant Jupiter shines to its left, as shown above. Although they look close together, Jupiter is 1,660 times farther away than the Moon — and 40 times larger in diameter.

Algol is at minimum light for a couple hours centered on 8:56 p.m. EST.

Mercury and Venus at their closest together, Jan.10, 2015
Catch Mercury and Venus shining closest together this as twilight fades on Saturday evening the 10th. Little Mars looks on from their upper left.

Thursday, January 8

Mercury and Venus are within 1° of each other, low in the southwest in evening twilight, from now through next Monday. Think photo opportunity!

Mercury, Venus, and Mars are all on the far side of the Sun from us now. Venus is currently 13 light-minutes from Earth, Mercury is 9 light-minutes, and Mars is 17, compared to the Sun's 8.

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.

Saturday, January 10

This evening Venus and Mercury are at their closest together low in the sunset, 0.7° apart. Look for them above the southwest horizon about 45 minutes after sundown.

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 10 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 will always mark 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.

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

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.

Mercury is creeping up to a close pairing with Venus; look for them in low the southwest in the afterglow of sunset. Mercury is magnitude –0.8; Venus shines 17 times brighter at magnitude –3.9. On January 2nd they're still 2.5° apart. They'll shine closest together, 0.7° apart, on the 10th. The farther south you live, the higher above the southwest horizon they'll appear.

Mars (magnitude +1.1, in eastern Capricornus) glows in the southwest to the upper left of Venus and Mercury. It sets around 8 p.m.

Jupiter (magnitude –2.4, in western Leo) rises in the east-northeast around 8 p.m. About 45 minutes later, fainter Regulus (magnitude +1.4) rises below it. By dawn they shine in the west — with Regulus now to Jupiter's upper left.

Saturn (magnitude +0.6, between Libra and Scorpius) glows in the southeast before and during dawn. As dawn brightens, look below it (by 11°) for Antares twinkling away.

Uranus (magnitude 5.8, in Pisces) and Neptune (magnitude 7.9, in Aquarius) are in the southwest just after dark. Uranus is still high, but Neptune has sunk much lower.

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)


Image of ctj


January 5, 2015 at 10:09 am

is there any chance that comet lovejoy can be added to the skyweek app?

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Image of Kevin-Ritschel


January 6, 2015 at 11:18 pm

Tonight, Jan 6 near Paso Robles, CA Comet Lovejoy was noticeably visible to the naked eye by 6:30 PM PST (as a fuzzy star), even visible after moonrise about 7 PM. About the same size as the extended portion of M42. Easy in binoculars and small scopes (I observed with 8x42's and a 62mm refractor, f/8 and 20mm ocular).

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