Friday, December 28
• Last-quarter Moon tonight (exact at 4:39 a.m. on the 29th EST). The Moon, half-lit, rises in Virgo around midnight. By the beginning of dawn on Saturday the 29th the Moon is high in the south, about a fist and a half upper right of Spica, and close above the telescopic double star Gamma (γ) Virginis — as shown here.
Saturday, December 29
• Before dawn on Sunday the 30th, the waning Moon shines upper left of Spica as shown here. Much farther upper left of the Moon is Arcturus, pale yellow-orange (out of the frame here). Far to the Moon's lower left are bright Venus, then Jupiter, then Mercury, in a diagonal line.
Sunday, December 30
• Orion shines in the east-southeast after dark, higher every week, but in early evening his three-star Belt is still nearly vertical.
The Belt points up toward Aldebaran and, even higher, the Pleiades. In the other direction, the Belt points down to where bright Sirius will rise around 7 p.m. (depending on your location) to twinkle furiously.
Monday, December 31
• Midnight stars. After the cheering and noisemaking when 2019 arrives, step outside into the silent dark. Sirius shines high in the south, as high as you'll ever see it from your latitude. Upper right of it stands Orion. Upper left of Sirius shines Procyon.
Below Sirius and a bit left, you'll find the triangle of Adhara, Wezen, and Aludra (right to left), the hindquarters and tail of Canis Major.
Lower left from there are the Milky Way mysteries of Puppis, now exposed and awaiting your exploration with binoculars and sky charts.
• By dawn on New Year's morning, the Moon hangs upper right of Venus, with Jupiter and then Mercury farther to their lower left.
Tuesday, January 1
• After dinnertime now, the enormous Andromeda-Pegasus complex runs from near the zenith far down to the west.
Near the zenith, spot Andromeda's high foot: 2nd-magnitude Gamma Andromedae (Almach), slightly orange. Andromeda is standing on her head, on the Great Square of Pegasus. The Great Square is about halfway down from the zenith to the west horizon, balancing on one corner. Mars shines left of the bottom corner.
Down from the Square's bottom corner run the stars outlining Pegasus's neck and head, ending at his nose: 2nd-magnitude Enif, due west and also slightly orange.
• In the dawn of Wednesday the 2nd, spot the waning crescent Moon between Venus and Jupiter, as shown above.
Wednesday, January 2
• The Pleiades cluster glitters high in the southeast these evenings, no bigger than your fingertip at arm's length. Its brightest star is Alcyone. How many Pleiads can you count? Take your time and keep looking. Most people can count 6. With sharp eyesight, a good dark sky, a steady gaze and careful use of averted vision, you may be able to make out 8 or 9. Binoculars can reveal dozens.
• In the dawn of Thursday the 3rd, the Moon is left of Jupiter, as shown above.
Thursday, January 3
• As dawn brightens on Friday the 4th, look low in the southeast for the thin crescent Moon guiding you to Mercury below it, as shown above.
• Earth is at perihelion, its closest to the Sun for the year (only 3% closer than at aphelion in July).
Friday, January 4
• Here is is January, and the Summer Triangle is still in view — if you look early after dark. Vega is the brightest star low in the northwest. The brightest one above it, and perhaps a bit left, is Deneb. Look for Altair farther to Vega's left and perhaps even lower.
Saturday, January 5
• As we enter the very coldest time of the year, the dim Little Dipper (Ursa Minor) turns to hang 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. Its handle is very low and its bowl is to the upper right.
And Cassiopeia, a flattened letter M, is beginning to tilt nearly overhead in the north-northwest.
• New Moon (exact at 8:28 p.m. EST).
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.
Once you get a telescope, to put it to good use you'll need a 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 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) and 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, or the bigger Night Sky Observer's Guide by Kepple and Sanner.
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 (meaning heavy and expensive). 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."
This Week's Planet Roundup
Mercury (magnitude –0.4) is getting lower in the dawn. Look for it just above the southeast horizon about 40 minutes before sunrise. It's lower left of brighter Jupiter, which in turn is lower left of even brighter Venus. Mercury and Jupiter move farther apart every day.
Venus (magnitude –4.7, in Virgo) rises as an eerie "UFO" above the east-southeast horizon more than two hours before the first light of dawn. By the time dawn arrives, Venus is the brilliant "Morning Star" dominating the southeast. In a telescope, Venus is almost half sunlit.
Mars (magnitude +0.4, in Pisces) shines highest in the south in late twilight and sets by 11 or so. In a telescope it's gibbous and quite small, about 7½ arcseconds from pole to pole.
Jupiter (magnitude –1.8, in Ophiuchus) shines in the east during dawn, lower left of brighter Venus.
Look for Mercury down to Jupiter's lower left. Look closer to Jupiter's lower right for orange Antares.
Saturn is hidden behind the glare of the Sun.
Uranus (magnitude 5.8, at the Aries-Pisces border) is highest in the south shortly after dark. It's visible in binoculars if you have a good finder chart and if you know the constellations well enough to see where to start with the chart.
Neptune, in Aquarius, is lower in the southwest right after dark and more difficult at magnitude 7.9. Finder charts.
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 or GMT) minus 5 hours.
"Science is built up of facts, as a house is with stones. But a collection of facts is no more a science than a heap of stones is a house."
— Henri Poincaré (1854–1912)