Monday, May 29
You should be able to catch a glimpse of Mercury in the predawn sky early this week. The innermost planet lies 5° above the eastern horizon 30 minutes before sunrise. Glowing at magnitude –0.2, Mercury should stand out through binoculars if you have an uncluttered horizon. A telescope reveals the planet’s 7"-diameter disk, which appears 60 percent illuminated.
Tuesday, May 30
Jupiter appears halfway to the zenith in the southern sky during twilight this week and doesn’t set until around 3 a.m. local daylight time. The brilliant planet shines at magnitude –2.3 among the background stars of Virgo, some 10° northwest of the Maiden’s brightest star, 1st-magnitude Spica. When viewed through a telescope, Jupiter’s disk spans 41" and shows a wealth of detail in its massive atmosphere.
Wednesday, May 31
Neptune rises around 2 a.m. local daylight time and appears about 20° above the southeastern horizon 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 13' southeast of 6th-magnitude 81 Aquarii. The star shines some five times brighter than the planet. You can confirm your sighting of Neptune through a telescope, which reveals the planet’s 2.3"-diameter disk and blue-gray color.
Thursday, June 1
First Quarter Moon occurs at 8:42 a.m. EDT. The half-lit orb rises around 1 p.m. local daylight time, appears highest in the south shortly before sunset, and sets around 2 a.m. The Moon spends this evening among the background stars of southern Leo the Lion.