Skywatch Line for Monday and Tuesday December 6th, and 7th, 2021

This is the Dudley Observatory’s Skywatch Line for Monday and Tuesday December 6th, and 7th, written by Joe Slomka.

The Sun sets at 4:21 PM; night falls at 6:03. Dawn begins at 5:31 AM and ends with the Sun rising at 7:13.

Monday’s waxing Moon rises in Sagittarius at 9:58 AM and sets in the southwest at 6:46 PM, 10% illuminated, 33 arc-minutes large and 5° above the horizon. Tuesday’s Moon is now in Capricornus, rising at 10:51 AM and setting at 8:01 PM, 32 arc-minutes, 18% lit and 14° high in the southwest; it also lies 3.5° below Venus.

For the next three nights, the Moon, Venus, Saturn and Jupiter are easily visible in the southwest between 4 and 6 PM. Venus is first, in Sagittarius, blazing with minus 4th magnitude, 42 arc-seconds, 8° high and sets at 6:58 PM. Saturn is next, shining with zero magnitude, 15 arc-seconds in size, sets in Capricornus at 8:35 PM and 20° high. Jupiter lies 15° East of Saturn, shares Capricornus, shines with minus 2nd magnitude, twice Saturn’s apparent size, 31° high and sets at 9:53.

Neptune continues the planetary parade, trailing 24° East of Jupiter, in Aquarius, 8th magnitude, 2 arc-seconds small, 42° high and sets at 11:58 PM. Uranus, half across the sky, in Aries, glimmers with 5th magnitude, 3 arc-seconds small, highest at 9:27 PM with 61° and sets at 4:26 PM.

Dwarf Planet 1Ceres is found 21° East of Uranus, Taurus, 7th magnitude, highest at 20:51 PM with 61° and sets at 6:04 AM.

Note that all these heavenly bodies trace a straight line across the sky. This is the Ecliptic, the path of Sun, Moon and planets.

Mars, in Libra, rises at 5:37 AM, shining with first magnitude, sized 3 arc-seconds, set during daylight and peeks 3° above the eastern horizon at 6 AM.

Astronomers are in luck this year. We have a “Christmas star” – actually a bright comet. Comet Leonard (C/2021 A1) was discovered this January. It is now found in our skies and will be visible until Christmas. It shines in Bootes at 5th magnitude, 7 ½° to the upper left of the bright star Arcturus.

Every history student knows the December 7th marks the 80th anniversary of the Japanese attack on Pearl Harbor. Few people are aware of the date’s astronomical significance. The Japanese high command chose that date because the eighteen-day-old Moon rose before midnight and shone at 87 percent, permitting planes to launch and fly to their targets. However, the Moon almost helped foil the surprise raid. The Condor, an American minesweeper spotted a submarine periscope silhouetted against the moonlight. The Condor called the Ward, a destroyer, who attacked a second submarine and radioed the incident to headquarters. However, that report was not heeded. Had that information been acted upon, the American fleet would have had at least an hour and a half to prepare.

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