Skywatch Line for Monday and Tuesday May 27th and 28th, written by Joe Slomka
This is the Dudley Observatory’s Skywatch Line for Monday and Tuesday May 27th and 28th, written by Joe Slomka.
The Sun sets at 8:24 PM; night falls at 10:32. Dawn begins at 3:13 AM and ends with Sunrise at 5:22.
Monday’s Moon is heading toward Last Quarter. It sets at 8:38 AM in western Sagittarius and will not be visible until Tuesday, when it shifts to southern Capricornus, 23° high, 32 arc-minutes in size and 75% illuminated. Tuesday’s Moon rises at 12:40 AM and sets at 9:54 AM. The Moon rises at 1:13 AM on Wednesday.
The evening sky is still empty of planets. But, two comets are still visible by 9 PM. 13P/Olbers can still be spotted in northwestern Auriga, glowing with 8th magnitude, 97% lit, is 18° high rises at 5:38 AM and sets at 11:24 PM. Observers who have more powerful telescopes can see C/2023 A3 in southern Virgo, rising at 2:33 PM, 10th magnitude, 96% lit 49° high and sets at 2:59 AM.
Dawn sees more planets. Saturn is first, in southeastern Aquarius, rising at 2:14 AM, first magnitude, 16 arc-seconds, and 27° high at 5 AM. Neptune follows, 11° behind Saturn, rises at 2:35 AM, 8th magnitude, 2 arc-seconds and 25° high. Mars, 22° behind Neptune, shares eastern Pisces with Neptune, rising at 3:23 AM, also 1st magnitude, 5 arc-seconds and 17° high. Elusive Mercury is next, 27° from Mars, rising in Aries at 4:38 AM, zero magnitude, 6 arc-seconds, only 4° high due to its proximity to the Sun. Finally, northeastern Uranus trails Mercury by 5°, rising in Taurus at 4:43 AM, closer to the Sun than Mercury, 5th magnitude, 3 arc-seconds and 3° above the horizon. Venus and Jupiter are still too close to the Sun. All visible planets set during daytime.
When you are done observing comet C/2023 A3, turn your attention to the close star Porrima. The Latin name refers to a Goddess of Prophesy. The star lies midway between Spica, in Virgo, and Denebola, Leo’s tail. Porrima is a double star; both stars are nearly identical. They are about the same brightness, third magnitude, the same mass, about 1.5 times the Sun, are sun-like, but significantly brighter and warmer. Like the Sun, Porrima and its companion are main sequence stars, fusing hydrogen into helium. Porrima was among the first double star systems discovered. Sir John Herschel calculated its orbit in 1833. They share a highly elliptical orbit, which makes one cycle in about 169 years. An observer, with high power eyepieces in the telescope, can see them about 1.7 arc-seconds apart.
Clear Skies Joe Slomka