May ends. The time of Jupiter's culmination (when it's highest in the south and best seen in telescopes) backtracks from about 4 a.m. to well before 2 a.m. in May. The banded giant continues to retrograde among the stars of southern Ophiuchus, its distance from Antares in Scorpius decreasing from more than 14½° to about 12° during the month. Mars December solstice Uranus Mercury Sept. equinox March equinox Jupiter Venus Sun Neptune Saturn MIDDLE NIGHT TO DAWN Saturn rises in the middle of the night throughout May and starts reaching the meridian around the first glimmers of morning twilight by the end of the month. Saturn brightens noticeably, from magnitude +0.5 to +0.3 in May, while its equatorial diameter swells to just short of 18″ wide. The span of the golden planet's rings grows to more than 40″, and their tilt starts to increase from a temporary minimum of 23.5° from horizontal. Saturn retrogrades back in eastern Sagittarius, slowly gaining on the Teaspoon asterism. The separation of Saturn from Jupiter increases to around 29° by the close of May. DAWN Venus rises about an hour before the Sun in May but is particularly low for observers at mid-northern latitudes. The always-brilliant planet shines at Pollux Castor Earth June solstice ORBITS OF THE PLANETS The curved arrows show each planet's movement during May. The outer planets don't change position enough in a month to notice at this scale. its minimum magnitude of -3.8 now. Venus's disk is about 11″ wide and about 91% illuminated on May 18th. That's the day that a telescope might reveal 6thmagnitude Uranus 1.4° north of Venus. MOON PASSAGES The Moon is a slender crescent hanging 3° upper right of Aldebaran in the dusk on May 6th. The next night, the waxing lunar crescent is less than ½° left of Zeta (ζ) Tauri and forms a compact line with Mars some 3° to 4° to its right or upper right and similarly bright Beta Tauri even farther right. The first-quarter Moon is 8° to 9° right or upper right of Regulus on the evening of May 11th, while the waxing gibbous Moon is closer to the left of Regulus the next evening. The waning gibbous Moon is around 4° degrees to the right of bright Jupiter on the morning of May 20th. The thinning gibbous Moon floats some 7° to the right of Saturn on the morning of May 22nd, and closer to the lower left of Saturn the next morning. ¢ Contributing Editor FRED SCHAAF has been writing about the skies above us for more than 40 years. Dusk, May 19 May 19-20 May 22 - 23 1 hour after sunset Around 4 am Around 4 am GEMINI Saturn Moon May 20 Jupiter Moon May 19 Moon May 22 Moon May 23 Mars Antares M35 Mars is on the cluster's NE edge! (Use a scope.) S A G I T TA R I U S SCORPIUS Betelgeuse Looking West-Northwest Looking South-Southwest Looking South s k y a n d t e l e s c o p e . c o m * M AY 2 0 1 9 47http://www.skyandtelescope.com