Skywatch Line for Monday and Tuesday June 5th, and 6th, 2023

This is the Dudley Observatory’s Skywatch Line for Monday and Tuesday June 5th, and 6th, written by Joe Slomka.

The Sun sets at 8:30 PM; night falls at 10:43. Dawn begins at 3:05 AM and ends with the Sun rising at 5:18.

Southern Sagittarius accommodates the Moon on both nights. Two days past full, the Moon rises at 10:49 PM, 32 arc-minutes in size, 95% illuminated, and sets Tuesday at 7:18 AM. Tuesday’s rises at 11:42 PM, same size but 1° thinner and sets at 8:35 AM on Wednesday.

Western Venus and Mars share Cancer. Venus is brighter and easily located. It blazes with minus 4th magnitude, 24 arc-seconds, 48% lit, 27° high at 9 PM and sets at 11:40 PM. Sunday saw Venus at Greatest Eastern Elongation, from now on it slowly creeps toward the Sun. Mars, 9° from Venus, glimmers with 1st magnitude, 5 arc-seconds, 93% crescent, 32° high at 9 PM and sets at 12:04 AM. They crawl toward each other, but do not meet, a situation called a “Quasi Conjunction”. Mars also lies 1° from M-44, the “Beehive” – an open cluster of hundreds of stars. It is best observed using binoculars during late Dusk. Dwarf planet 1Ceres continues to shine with 8th magnitude near Leo’s tail and appears one-half of an arc second, 96% lit, highest at 8:04 PM and sets at 2:53 AM.

Remaining planets occupy Dawn skies and set during daytime. Saturn, in Aquarius, continues climbing southward and brightening, shining with 1st magnitude, 17 arc-seconds, rising at 1:17 AM and 31° high at 4:47 AM; the famous rings are tipped 7° towards us. Neptune, 20° to Saturn’s left in Pisces, glows with 8th magnitude, 2 arc-seconds, rises at 2:02 AM and is 29° high. Jupiter shares Aries with Mercury and Uranus. Jupiter becomes more prominent, glistening with minus 2nd magnitude, a large 34 arc-seconds, rises at 3:25 AM and is 15° high. Mercury and Uranus are bunched in brightening East. Mercury, now 23° from the Sun, shines with zero magnitude, 7 arc-seconds, rises at 4:20 AM, 54% lit, but only 4° high, gradually sinking into the solar glare. Uranus twinkles with 5th magnitude, 3 arc-seconds, rises at 4:05 AM and 7° high.

Mars rests close to the Beehive open star cluster, also known as M-44. The word “Beehive” is actually a nickname. The formal name is Praesepe (Latin for “manger”). Greek legends call stars Delta and Gamma the Northern and Southern donkeys; inspiring a manger to feed them.

This star cluster is bright enough for naked-eye viewing. In 250BC, Aratus of Soli termed it “little mist”.  Hipparchus, in 120 BC, described it as “little cloud”. In 1610, Galileo turned his newly built telescope toward it and declared it a “mass of over 40 small stars” and even drew a sketch. Binoculars show it as a star cluster; the smallest telescopes reveal between 50 and 100 stars. A dozen stars shine at 7th magnitude or brighter. Observation reveals that larger stars are clumped towards the center, while lighter stars form the edges. Studies show that M-44 shares a common motion with the Hyades, and maybe a mutual origin. Two Jupiter-sized planets were discovered among the outlying stars; these are the first “hot Jupiters” found in an open star cluster.