You've probably never seen it rise that far north over your landscape and you might never again, at least when it's this close to full. So as twilight fades, note carefully where the Moon comes up over your horizon. Tonight everything lines up this year the north edges of both tilts nearly coincide, and tonight that is where the bright almost-full Moon stands. That farthest-north side of the Moon's orbit precesses westward around the entire ecliptic with a period of 18.6 years (the "precession of the lunar nodes"). That's less than 1° from the Moon's greatest possible ecliptic divergence its orbit is inclined to the ecliptic by 5.14°. Second, this evening the Moon stands 4.3° north of the ecliptic itself. Why is this? First, the Moon is at the northernmost part of the ecliptic (which is at the Gemini-Taurus border) the ecliptic is inclined 23.4° with respect to the celestial equator. That's because the Moon is just about as far north on the celestial sphere as you can ever possibly see it. As night deepens, watch for Beta Tauri, magnitude 1.6, to come into view only about a fifth as far to the Moon's upper right. Bright Capella, magnitude 0, sparkles about two fists to the Moon's upper left. ■ The Moon, just past full, rises in the northeast in mid-twilight. By about 11 p.m., it plants itself more or less upright on the northwest horizon. At nightfall the shaft of the cross extends lower left from Deneb. The brightest star above it is Deneb, the head of the big Northern Cross formed by the brightest stars of Cygnus. ■ Vega still shines brightly well up in the west-northwest after dark. This evening the glary Moon is just 1° or 2° from the delicate Pleiades (evening for North America). Monday morning EST, about halfway between). ■ Full Moon, both this evening and tomorrow evening (because it's exactly full at 4:16 a.m. Watch Cas turn around to become a flattened M, even higher in the north, by late evening. ■ As the stars come out, the Cassiopeia W stands on end (its fainter end) high in the northeast. Comparison-star chart.Īt any random time you glance up at Algol, you have only a 1-in-30 chance of catching it at least 1 magnitude fainter than normal. ■ Algol in Perseus should be at its minimum brightness, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 7:44 p.m. Will its light drown out those brightest two stars of Aries? The bright waxing gibbous Moon is passing Jupiter. They are the two brightest things in the evening sky. ■ The Moon shines near bright Jupiter this evening and tomorrow evening, as shown below.
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