Some daily events in the changing sky for December 28 – January 5.
Two comets float high in the dark, moonless evening sky this week. They're not very far apart. Comet Holmes remains in Perseus, dim but big — more than 1° across. Look for it north of Algol all week, and bring binoculars. Comet 8P/Tuttle is much tinier, and it's greenish. It was about magnitude 6.5 on December 26th and should be about 6.0 this week.
Watch Tuttle race southward from night to night. It moves from Andromeda into Triangulum and skims the western edge of M33, the Triangulum Galaxy, on the evening of December 30th. (Closest approach is around 23h Universal Time on the 30th, just after dark on the East Coast of North America. Think photo opportunity!). Then in early January Comet Tuttle crosses Pisces and part of Cetus. See the article and charts in the January Sky & Telescope, page 73, and the brief version online. Moonlight returns to brighten the sky around January 12th.
Friday, December 28
Saturday, December 29
Sunday, December 30
Monday, December 31
Tuesday, January 1
Wednesday, January 2
Thursday, January 3
And prepare for the cold! Quad watching is the coldest activity you will ever do near your home. It's January, you'll be out for a long stretch at the coldest time of the 24-hour cycle, you'll be lying motionless rather than moving and generating heat as most people do when outdoors in winter, and whenever the sky is clear, there's extra chill from radiational cooling. Electric hot pads inside your coat, a sleeping bag wrapped around you... treat this as a winter adventure.
Friday, January 4
Saturday, January 5
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 standard is Sky Atlas 2000.0) 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 enchanting though increasingly dated Burnham's Celestial Handbook). Read how to use them effectively.
More beginners' tips: "How to Start Right in Astronomy".
This Week's Planet Roundup
Mercury, Jupiter, and Pluto are still "combust": an old astronomical term meaning hidden in the glare of the Sun.
Venus (magnitude –4.1, moving from Libra to Scorpius) is the bright "Morning Star" shining moderately low in the southeast before and during dawn. Well below it, look for much dimmer Antares sparkling orange-red.
Mars is just past opposition, shining bright yellow-orange (magnitude –1.5) in the eastern evening sky as it moves from Gemini into Taurus. It's highest toward the south around 11 or midnight — near the zenith, in fact, for observers at mid-northern latitudes.
Mars diminishes slightly in apparent size this week, from 15.6 to 15.1 arcseconds in apparent diameter. It's falling behind us as Earth moves ahead of it in our faster orbit around the Sun. For all about observing Mars with a telescope, see the guide and Martian surface-feature map in the November Sky & Telescope, page 66. A short version is online.
Saturn (magnitude +0.7, in Leo) rises in the east around 9 or 10 p.m. It's highest in the south a couple hours before the first light of dawn. Fainter Regulus (magnitude +1.4) is 9° to Saturn's upper right after they rise, and to Saturn's lower right when they fade out in the glow of dawn high in the southwest. Only a little dimmer than Regulus is Gamma Leonis (magnitude +2.1), 8° to Regulus's north. The three make a striking triangle.
Neptune (magnitude 7.9, in Capricornus) is getting low in the southwest right after dark.
All descriptions that relate to your horizon or zenith — including the words up, down, right, and left — are written for the world's midnorthern latitudes. Descriptions that also depend on longitude (mainly Moon positions) are for North America. Eastern Standard Time (EST) equals Universal Time (UT, UTC, or GMT) minus 5 hours.
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