Evan Hazard: Few planets, bright winter constellations
Central Daylight Time starts March 10. Set your clocks ahead one hour the night before.
The unusual news is Comet PanSTARRS, which will be visible above the western horizon after sunset from about March 12-24 (March 16 is St. Urho’s Day). You will need binoculars; it’s not very bright and will be against a bright background. If a tail is visible, it will point away from Sol. March 12 it will be left of thin crescent Luna. For Sky and Telescope’s details, see: http://www.skyandtelescope.com/skytel/beyondthepage/Comet-PanSTARRS-Updates-185665152.html . The management is not responsible for clouds.
It’s another lean month for planets. Dim Mars is low in the west, visible only with binoculars in the bright evening twilight. During March, Jupiter passes slowly east (left) above the Hyades high in the west. Saturn rises after 10 CST St. David’s Day, March 1, and only an hour after dusk by April Fool’s. (David is patron saint of Wales; I’m in trouble with some readers if I fail to mention that.)
Mercury has a poor morning apparition this March, and Venus is around back of Sol. Sol, on the other hand does one of its things: at 6:02 a.m. CDT March 20, it crosses the celestial equator. That’s the vernal equinox, the start of astronomical spring, and the “at 6:02 a.m. CDT” above raises a question you may have: “How come it’s 20 March some years and 21 or 22 March others?”
Well, one answer is that every four years, Feb. 29 moves March dates a day later. But the other is, if it’s 6:02 a.m. March 20 in Minnesota, it’s the wee hours March 21 in China. Equinoxes, solstices, full moons, new moons, and such are each an astronomical instant that is independent of one’s location on Earth. Only if the event happens at exactly midnight on the International Date Line (180 degrees longitude, with political irregularities) does it occur on the same date everywhere.
The evening sky, especially in the southeast, is dominated by several prominent winter constellations. From right to left are Taurus (with reddish Aldebaran, just below Jupiter for now), Orion, Auriga, Gemini, Canis Major (with Sirius, the brightest nighttime true star), Canis Minor (with bright Procyon), and finally Leo, with bright Regulus. Nothing bright thereafter until we come to reddish Arcturus in the spring constellation Boötes above the ENE horizon.
Perseus is still up in WNW; March minima of its eclipsing variable Algol include 12:08 a.m. March 4-5 and 8:58 p.m. March 7 both CST; and then, both 11:43 p.m. CDT March 27 CDT and 8:32 p.m. CDT March 30.
Evan Hazard also writes “Threescore and Ten” for The Pioneer’s “Prime Time.”