Skywatch Line for Friday, May 22, through Sunday, May 24, written by Sam Salem
This is Dudley Observatory’s Skywatch Line for Friday, May 22, through Sunday, May 24, written by Sam Salem.
On Friday, Sun rises at 5:26am and sets at 8:18pm; Moon sets at 1:18am and rises at 11:32am.
On Friday evening, the waxing crescent Moon will be near Regulus, the brightest star in Leo the Lion. Spot 1st-magnitude Regulus just a couple degrees to the Moon’s upper left. Regulus is the bright Star at the bottom of a backward question-mark pattern of stars known as the Sickle. The Sickle of Leo extends almost directly right from Regulus, with its cutting edge facing down. The Sickle is a little more than a fist at arm’s length long. On Saturday, the 1st quarter Moon will lie beside the Sickle. They’ll set after midnight.
The of 1st quarter Moon will fall at 7:11 am on Saturday. First quarter Moon rises around noon and sets around midnight. Watch for a 1st quarter Moon high in the sky at sundown. On Saturday, with the Moon just a half day past first quarter, the terminator between lunar day and night still crosses almost perfectly straight across the Moon’s face. In a telescope after dark the terminator uncover Mare Imbrium in the north, highlighting the crater pair Aristillus and Autolycus on Imbrium’s flat floor. The Moon’s Imbrium basin is bordered by the Alps and Apennines, which are among the highest mountains on the lunar surface. Farther south, the terminator highlights some of the largest craters of the Southern Highlands.
Use binoculars to spot Mars and Saturn are low in the east in the brightening dawn. Saturn is the higher and brighter of the two, magnitude +0.9. Mars is much lower and somewhat fainter, magnitude +1.3. Look for Mars almost two fists to Saturn’s lower left, a little farther every morning. As the month proceeds, Saturn will rise more quickly than the slowly ascending Mars.
Venus, magnitude –3.9, shines in the west-northwest during evening twilight. It doesn’t set until about 50 minutes after complete dark. High to Venus’s upper left shines Jupiter. Capella, the brightest star in the constellation Auriga the Charioteer, sits somewhat a similar distance to Venus’s upper right.
Jupiter, magnitude –1.9 in the constellation Gemini, shines in the west in twilight about 25° to Venus’ upper left. Watch the two planets close in toward each other for the next few days. They’ll pass just 1.6° apart at their conjunction on June 9th. Look upper right of Jupiter for Pollux and Castor, and farther lower left of Jupiter for Procyon, the brightest star in the constellation Canis Minor.
Two of Jupiter Galilean moons cross the planet’ disk on Friday evening. Use a telescope to watch Jupiter shortly after sunset to see Io alone to the planet’s west, with Ganymede, Europa, and Callisto all to the east. Ganymede is closing in on the eastern limb and begins transiting first, starting at 9:57 pm. Europa reaches the eastern limb and begins transiting 2 hours later, with Ganymede slightly more than halfway
across. The two moons continue across the disk together, and the planet sets with the pair visible against the cloud tops for observers in the eastern U.S.
Uranus is in conjunction with the Sun at 10 am pm Friday. It will reappear in the sky next month, visible in the morning.