Skywatch Line for Monday and Tuesday November 20th, and 21st, 2023
This is the Dudley Observatory’s Skywatch Line for Monday and Tuesday November 20th, and 21st, written by Joe Slomka.
Sun sets at 4:28 PM; night falls at 6:07. Dawn begins at 5:15 AM and ends with Sun rising at 6:54.
Southeastern Aquarius houses the Moon on both nights. Monday’s First Quarter Moon rises at 1:17 PM, 32 arc-minutes in size, 55% illuminated, 29° high at 7 PM and sets at 11:56 PM. The Moon lies about 16 degrees from the Moon and the bright star Formalhaut. Tuesday’s Moon rises at 1:41 PM, same size, 67% lit and sets at 1:12 AM on Wednesday.
Twenty-one degrees from the Moon lies comet C/2023 H2 (Lemmon). Recently discovered, it smolders with 12th magnitude, large telescope is needed to see it. It appears 60% lit, 15° high at 7 PM, visible after 6 PM and sets at 9:28; it orbits the Sun once every 3,866 years! It is post maximum and will appear dimmer and gradually fade away.
Mars remains too close to the Sun. Southern Saturn is the first planet to be seen; near the Moon, it rises at 12:59 PM, glimmering with minus 8th magnitude, 17 arc-seconds in size, highest at 6:09 PM, it is 33° high at 7 PM and sets at 11:19. Neptune follows, rising in southern Pisces at 1:52 PM, shimmering with 8th magnitude, 2 arc-seconds, 43° high, and sets at 1:29 AM.
Eastern Aries contains Jupiter and Uranus; both are well up by Sunset. Jupiter flares with minus 2nd magnitude, a large 48 arc-seconds, 60° highest at 10:20 PM and sets at 5:12 AM, Tuesday. Monday, the moon Io begins to march across the planet at 8:49 PM, followed by its shadow at 9:17 and ends at 11:27 PM. Tuesday, the Great Red Spot (a giant storm) begins its trek at 4:16 AM. Uranus, one week after Opposition, trails Jupiter, shining with 5th magnitude, 3 arc-seconds, highest at 6:09 PM, 33° high at 7 PM and sets at 6:19 AM.
Mercury returns, found in the Southwest, gleaming with zero magnitude, 5 arc-seconds, 2° high at 5 PM, 87% lit and sets at 5:11 PM.
Venus appears in southeastern Virgo, at 3:04 AM, blazing with minus 4th magnitude, 18 arc-seconds 29° at 6 AM and sets at 2:35 PM.
Jupiter’s Great Red Spot has been continuously observed for three centuries; first, by Giovanni Cassini in 1615. The Spot changes. It is not red now, but a pale pink. When measured in the 1800’s, the storm was 25,000 miles wide. In 1979, the Voyager spacecraft imaged it at 15,534 miles. In early 2023, NASA measured it as 9,165 miles long and 10,500 miles high – the smallest it’s been observed. The Spot rotates once per 6 days and wind speeds between 270 and 420 mph. Dwindling has accelerated. It now contracts at a yearly rate of 0.194° long and 0.048° wide. What was 3 earths in size, is now barely 1 earth.
The cause for shrinkage is unknown. Should the Great Red Spot disappear, astronomers are uncertain what would happen. It could reappear, or never return. Remember, this is a weather system, which, like all storms eventually end.
Clear Skies Joe Slomka