Evan Hazard/Northland Stargazing:An unsatisfying answer to burning questions are sometimes norm in science
The answer as of this writing, Nov. 17, is “We don’t know,” often the appropriate answer in science.
Winter solstice is at 11:11 a.m. Dec. 21, the shortest day of 2013. Earliest sunset will be Dec. 7, and latest sunrise about Jan. 4, but I won’t know that until the January “Sky & Telescopes” arrives.
Barring clouds, December evenings this year will boast two bright planets. Venus is a beacon low in the southwest all month, but, as it comes closer to us in its orbit, its night side is also turning toward us, so it becomes a distinct crescent in binoculars. If you have a youngster with sharp vision, take her outside and ask him what shape Venus is. Kids can often tell. Jupiter, in Gemini, rises after supper Dec. 1, but less than 30 minutes after sunset by New Year’s Eve. If you go out front to pick up your morning Pioneer early enough, Jupiter may still be visible high in the southwest predawn sky.
Mars rises before midnight, and gets earlier and brighter all month. Saturn rises about 5 a.m. in early December but about 3:30 a.m. at month’s end. Mercury is visible early December mornings below and left of Saturn. It brightens toward mid-month but also travels sunward and soon gets lost in Sol’s glare, passing around back of Sol at month’s end.
Geminid meteors will peak the night of Dec. 13-14, but moonlight may interfere. If you go out, put on many layers.
The winter Milky Way runs west to east, crossing just north of the zenith. In front of it lay some of our best known asterisms and constellations. Altair, Vega, and Deneb, the “summer triangle,” are still up in the west, then Cepheus, Cassiopeia, and Perseus overhead, and Auriga and Gemini in the WNW. (The extra “star” in Gemini is, of course, Jupiter.) Rising in the WSW is the hunter, Orion, with Messier 42, the “Great Nebula” in his sword, angling below the three stars in his belt. It is the nearest conspicuous star nursery, only some 1,345 light-years away, much farther away than the constellation’s bright stars. The nebula, some 24 light-years across, is only a bright region on the surface of the much larger and mostly dark Orion molecular cloud. The cloud’s interior has been studied at infrared and longer wavelengths that penetrate the cloud’s dust. There is a neat Wikipedia entry at http://en.wikipedia.org/wiki/Orion_Nebula .
December minima of Algol: 12:01 a.m., Dec. 10-11; 8:50 p.m. Dec. 13; and 5:39 p.m. Dec. 16.
Evan Hazard also writes “Threescore and Ten” for The Pioneer’s “Prime Time.”