The slow-build of planetary brightenings continues as Mars, Saturn, and Jupiter continue their march towards opposition in the southeastern sky in the early morning hours. After a spectacular run in the evening sky, Venus moves quickly towards the horizon this month on its way to conjunction with the Sun on June 3- but not before it makes an impressive rendezvous with Mercury after sunset. Add in a fine meteor shower on May 5-6 and you’re all set for a month of good stargazing. Here’s what to see in the night sky this month…
5-6 May. The Eta Aquarid meteor shower peaks. This is one of the finest meteor showers for observers in the southern-hemisphere and southern latitudes of the northern hemisphere where up to 40 meteors per hour are visible under ideal conditions. The event occurs as the Earth passes through the stream of debris of Comet 1/P Halley (i.e. Halley’s Comet). Predictions suggest it could be a good year for this meteor shower!
Look anywhere in the sky to see these fleeting meteors that trace their paths back to a point near the Circlet of Pisces, a little group of stars that emerges above the eastern horizon in the wee hours in early May. Northern star gazers can perhaps 10-15 meteors per hour. But the Eta Aquarids are often fast-moving and noted for leaving lingering trains of ionized gas in their wake. Occasionally an earthgrazer appears, a meteor that skims the atmosphere and leaves a persistent trail low over the horizon. This year a thick gibbous Moon brightens the sky for much of the night, but the Eta Aquarids are visible for a few days before the peak when the Moon is less of a factor.
7 May. Full Moon, 10:45 UT
12 May. The waning gibbous Moon passes close to Jupiter and Saturn in the southeastern sky before dawn. Jupiter lies 3.5o north of the Moon in Sagittarius, while Saturn lies about 4.7o to the northeast in Capricornus. All three fit into a binocular field of view just east of the ‘Teapot’ asterism in Sagittarius.
14 May. Last Quarter Moon, 14:03 UT
14-15 May. The waning Moon passes within about 4o Mars, which is a hands-width further to the east of Jupiter and Saturn in the pre-dawn sky. At magnitude +0.3 today, Mars slightly outshines Saturn and is far more orange in color.
21 May. Perhaps the highlight of the month: Mercury and Venus make a close approach in the western sky after sunset. Venus has had a great run in the west for the past few months, but the show comes to an end as the planet reaches superior conjunction with the Sun on June 3 and afterwards becomes visible in the morning sky. But on its way back towards the Sun, today Venus passes the smaller and more distant Mercury by about one degree.
To see this fleeting celestial rendezvous, you need a clear view of the western/northwestern horizon after sunset. Venus, far brighter than Mercury, has just 5.5% of the planet’s disk illuminated. It shines at magnitude -4.2 and spans a relatively large 53.4”, far larger than Jupiter ever gets, for example. Mercury spans just 6” and shines at magnitude -0.6, and appears 69% illuminated. The slender crescent Moon joins the two planets on May 23-24. Binoculars help pull these worlds out of the twilight glare and may reveal the crescent phase of Venus.
22 May. New Moon, 17:39 UT
23-24 May. A day-old crescent Moon emerges in the western sky just after sunset along with Mercury and Venus nearby. A pair of binoculars helps you pick these objects out of the twilight glare.
30 May. First Quarter Moon, 03:30 UT