This is the Dudley Observatory Skywatch Line for Wednesday, May 24th, and Thursday, May 25th, written by Louis Suarato.
Comet C/2015 V2 (Johnson) is well placed for viewing as it travels east to south through the constellation Boötes. Discovered by Astronomer Jess Johnson using the Catalina Sky Survey on November 3rd, 2015, Comet Johnson is now at 6.9 magnitude. The comet will peak in brightness in late June. Look about 30 degrees to the east of Arcturus for this binocular-visible comet. Look further south, and lower, for Jupiter. At magnitude -2.29, Jupiter will be the brightest object in the night sky, before Venus rises at 3:30 a.m. Thursday. Jupiter’s moon, Europa, begins its transit across the planet at 10:50 Thursday night. Two hours later, Io will join Europa. Four minutes later, Europa’s shadow will join the double Jovian moon transit. Saturn rises at 11 p.m. in Sagittarius. You’ll require a clear eastern horizon to see Mercury and the 3% illuminated, waning crescent Moon separated by 4 degrees before Wednesday’s sunrise. The New Moon occurs at 3:45 p.m. Thursday. Lunar perigee occurs 5 hours later, and will cause Perigean Spring Tides, when the gravitation pull of the close Moon induces the oceans to bulge, and creates higher, and lower, than normal tides. At the distance of 221, 958 miles from Earth, this will be the closest lunar perigee of the year.
There will be two extremely bright International Space Station passes over our region Wednesday and Thursday nights. Wednesday, beginning at 10:04 p.m., the -3.8 magnitude ISS will emerge from the west-southwest, pass through the constellation Hydra, continue through Leo and the Big Dipper, before crossing Cygnus and disappearing into the northeastern horizon. Thursday, the -3.7 magnitude International Space Station will rise from the southwestern horizon at 9:12 p.m., and pass close to Jupiter, sail by Arcturus, and pass the binary star Albireo in Cygnus before continuing northeastward.