Some daily events in the changing sky for December 19 – 27.
Friday, December 19
Saturday, December 20
Sunday, December 21
Monday, December 22
Tuesday, December 23
Wednesday, December 24
Thursday, December 25
Friday, December 26
Saturday, December 27
Several faint stars are in the vicinity; identify which pinpoint is Neptune using the chart of the whole little scene in the December Sky & Telescope, page 55.
Want to become a better amateur astronomer? Learn your way around the constellations. They're the key to locating everything fainter and deeper to hunt with binoculars or a telescope. For an easy-to-use constellation guide covering the whole evening sky, use the big monthly foldout map in each issue of Sky & Telescope, the essential magazine of astronomy. Or download our free Getting Started in Astronomy booklet (which only has bimonthly maps).
Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of maps; the standards are Sky Atlas 2000.0 or the smaller Pocket Sky Atlas) and good deep-sky guidebooks (such as Sky Atlas 2000.0 Companion by Strong and Sinnott, the even more detailed Night Sky Observer's Guide by Kepple and Sanner, or the classic Burnham's Celestial Handbook). Read how to use them effectively.
Can a computerized telescope take their place? 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, they note, "the sky never becomes a friendly place."
More beginners' tips: "How to Start Right in Astronomy".
This Week's Planet Roundup
Mercury (magnitude –0.7) is very low in the sunset but becoming easier to spot. Look for it in early twilight to the lower right of Jupiter. Bring binoculars. Mercury is closing in on Jupiter rapidly; they'll be in conjunction at December's end.
Venus (magnitude –4.3) is the "Evening Star" blazing in the southwest during and after twilight. In a telescope it's still fairly small (19 arcseconds wide) and gibbous (62% illuminated).
Mars remains hidden in the glare of the Sun.
Jupiter (magnitude –1.9) has pulled away far to Venus's lower right in evening twilight. Look early and low; Jupiter now sets around twilight's end. It's 18° from Venus on December 19th and 24° from it on the 26th.
Saturn (magnitude +1.0, near the Leo-Virgo border) rises around 11 p.m. and is highest in the south before dawn. Don't confuse Saturn with similarly-bright Regulus 22° (about two fist-widths at arm's length) to its upper right after they rise, and directly to its right at dawn.
A telescope shows that Saturn's rings have closed to only 0.8° from edge on. This is their minimum tilt for a while; they'll start opening again a little in January and finally close to exactly edge-on next September (when Saturn will, unfortunately, be in conjunction with the Sun).
Uranus and Neptune (magnitudes 5.9 and 7.9, respectively, in Aquarius and Capricornus) are in the southwest and south right after dark. Neptune is getting close to Venus. Use our article and finder charts or the chart in the September Sky & Telescope, page 63.
Pluto is in conjunction with the Sun.
All descriptions that relate to your horizon or zenith — 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) equals Universal Time (known as UT, UTC, or GMT) minus 5 hours.
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