Friday, May 25
Look high in the northwest after darkness falls this week and you’ll be greeted by the familiar sight of the Big Dipper. The Dipper is the sky’s most conspicuous asterism — a recognizable pattern of stars that doesn’t form a complete constellation shape. It makes up the body and tail of Ursa Major the Great Bear. Use the Pointers, the two stars at the end of the Dipper’s bowl, to find Polaris, which lies due north for everyone north of the equator. Polaris marks the end of the Little Dipper’s handle. On evenings in late May and June, the relatively faint stars of this dipper arc directly above Polaris.
Saturday, May 26
Neptune rises around 2:30 a.m. local daylight time and appears 15° high in the east-southeast as twilight commences. The distant world glows at magnitude 7.9, so you’ll need binoculars or a telescope to spot it. Fortunately, it lies near a brighter star that will guide you. This morning, Neptune stands 1.1° west-southwest of 4th-magnitude Phi (φ) Aquarii. You can confirm your sighting of Neptune through a telescope, which reveals the planet’s 2.3″-diameter disk and blue-gray color.
Sunday, May 27
The waxing gibbous Moon appears near brilliant Jupiter all night. The two were closest during the afternoon hours from North America (when they were below the horizon), and they slowly pull apart as the night progresses. Still, they make a pretty pair set against the backdrop of Libra the Scales. If it weren’t for the Moon, Jupiter would dominate the late evening sky. The giant planet reached opposition and peak visibility earlier this month, and it remains a stunning sight from shortly after sunset until morning twilight is underway. It appears in the southeastern sky during evening twilight and climbs highest in the south around 11:30 p.m. local daylight time. Shining at magnitude –2.5, Jupiter is the night sky’s brightest point of light once Venus sets shortly before 11 p.m. The giant world resides in Libra, 1.1° northeast of Zubenelgenubi (Alpha [α] Librae). When viewed through a telescope, the gas giant’s disk spans 44″ and shows stunning detail in its cloud tops.
Monday, May 28
Mars rises around 12:30 a.m. local daylight time and climbs 25° high in the south-southeast by the time twilight commences. Although it won’t reach opposition for another two months, the Red Planet appears noticeably brighter than it did just a week ago. Shining at magnitude –1.1 this morning, it is the second-brightest point of light in the morning sky after Jupiter. If you point a telescope toward Mars this morning, you’ll see a 15″-diameter disk with several subtle surface features. To learn more about the planet’s great summer show, see “Observe Mars at its best” in the May Astronomy.
Tuesday, May 29
Full Moon occurs at 10:20 a.m. EDT, but our satellite looks completely illuminated all night. You can find it rising in the east near sunset and peaking in the south around 1:30 a.m. local daylight time. The Moon spends the night among the background stars of southern Ophiuchus.
Wednesday, May 30
If you look at Jupiter through a telescope tonight, it will appear as if it has a “black eye.” The reason: The shadow of its moon Io appears in stark contrast to the bright jovian cloud tops. The action gets underway at 10:37 p.m. EDT, when Io itself first touches the planet’s eastern limb. The volcanic moon’s shadow follows 30 minutes later. You can track the pair crossing Jupiter for the next two hours. Io moves off the planet’s western limb at 12:45 a.m., followed by its shadow at 1:17 a.m.