This yr, Christmas Eve will convey an exquisite sight to the sky shortly after sundown: two shiny planets sharing the twilight with a skinny crescent Moon.
Look southwest about half-hour after sundown and also you’ll simply spot shiny Venus (magnitude –3.9) about 5° excessive. Simply 4° to its higher left (east) is Mercury, a dimmer magnitude –0.5. And standing to the planets’ left (east) is a fragile crescent Moon slightly below 4 p.c lit, exhibiting off a mere sliver of its jap limb.
Collectively, the trio create a triangle within the fading twilight that units round 6 P.M. native time. There’s no want for binoculars or a telescope to benefit from the present, although you probably have observing gear obtainable, you possibly can examine and distinction the planets’ disks beneath greater magnification because the sky grows darker. Venus is 10″ throughout and practically full, exhibiting off a 97-percent-lit disk. Mercury seems 7″ large and is slightly below half lit, its phase at 49 p.c. Solely these two planets present phases as a result of they lie nearer to the Solar than Earth.
Solar and Moon on December 24, 2022
Dawn: 7:20 A.M.
Sundown: 4:39 P.M.
Moonrise: 8:56 A.M.
Moonset: 6:03 P.M.
Moon Section: Waxing crescent (3%)
*Instances for dawn, sundown, moonrise, and moonset are given in native time from 40° N 90° W. The Moon’s illumination is given at 12 P.M. native time from the identical location.
Venus now sits about 1.62 astronomical models from Earth, whereas Mercury is 0.92 astronomical models away. (One astronomical unit, or AU, is the typical Earth-Solar distance.) Though Mercury orbits nearer to the Solar than Venus, due to the planets’ present areas of their orbits, Mercury is nearer to Earth proper now. Nonetheless, Mercury nonetheless seems smaller as a result of it’s lower than half the diameter of Venus, which is roughly Earth’s measurement.
Though nobody might mistake this specific celestial alignment for a “star,” some historians consider that the Star of Bethlehem, related to the primary Christmas, could have been an analogous assembly or conjunction of planets within the sky. And there’s one such conjunction arising: On Wednesday, December 28, Venus and Mercury will stand simply 1.5° aside within the night sky, nonetheless readily seen collectively, whereas the Moon could have moved on into Aquarius. A couple of hours later, early on the twenty ninth, Mercury will cross 1.4° due north of Venus, although the 2 will stay under the horizon then.
Keep tuned to our Sky This Week column for extra particulars on this occasion and others each day.
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