Mercury is visible as an early morning object from southern and temperate locations during the first week of May. The innermost planet shines at about magnitude -0.5 and can be seen a few degrees above the eastern horizon with much brighter Venus just above. On May 3rd, the very thin crescent waning Moon will appear 3 degrees from Mercury. For the final three weeks of the month, the planet is no longer visible as it passes through superior conjunction on May 21st.
From northern temperate latitudes, Mercury is unsuitably placed for observation throughout May.
Venus is positioned too close to the Sun to be visible this month from northern latitudes. For observers located further south, the brightest planet remains a morning object, low down, in morning twilight. It shines at magnitude -3.8, and on May 2nd, the crescent Moon passes 4 degrees south of Venus.
Mars, mag. +1.7, is visible in the early evening skies throughout May. From northern latitudes, the red planet can be seen at the beginning of the month for about 3 hours after sunset, although the visibility period reduces by over an hour by months end. From southern and temperate locations, Mars sets about 2 hours after the Sun.
On May 7th, the thin waxing crescent moon will pass 3 degrees south of the planet.
Jupiter continues to move retrograde in Ophiuchus and is well placed for observation in the evening sky. At the start of the month, the giant planet rises around midnight from northern latitudes, and even earlier for those located further south.
Jupiter brightens from magnitude -2.5 to -2.6, with its apparent size increasing from 43.5 to 45.8 arc seconds as the month progresses. With binoculars or small telescopes up to 4 Galilean moons are visible. A small scope will also reveal features such as the northern and southern equatorial bands and the Great Red Spot, although it has been diminishing in size for some time now.
The waxing gibbous Moon passes a couple of degrees from Jupiter on May 20th.
Saturn is visible in the evening skies moving retrograde in Sagittarius. The ringed planet is positioned west of Jupiter and rises a couple of hours after its brighter neighbor. During the month, Saturn's magnitude increases from +0.4 to +0.2 with its apparent diameter improving from 17.2 to 17.9 arc seconds. Because of their southerly latitudes, both Jupiter and Saturn are much better placed from southern latitudes. The planet's ring system is currently wide open and can easily be seen with a small refractor telescope scope.
On May 22nd, an occultation of Saturn by the Moon is visible from the South Africa.
Uranus, mag. +5.9, is in Aries. The planet passed by solar conjunction last month and reappears in the morning sky during May. For northern temperate observers, it's swamped by the bright early morning twilight for most of the month. However, at the tail end of May it should be visible with binoculars and small scopes above the eastern horizon, an hour or so before sunrise.
Observers located further south have it much better with the planet rising 3 hours before the Sun by months end. On May 18th and 19th, Uranus is positioned just over a degree north of Venus which acts as a useful marker.
Neptune, mag. +7.9, is now visible as a morning object. From southern locations it rises up to four hours before the Sun at the start of the month, improving by a couple of hours by month's end. Although never bright enough to be seen with the naked eye, Neptune can be spotted with binoculars or small telescopes. From northern temperate latitudes, Neptune is not as well placed, but can be seen in the early morning sky above the eastern horizon before sunrise, especially during the second half of the month.
The planet is in Aquarius near to star phi Aquarii (φ Aqr - mag. +4.2). On May 27th, the waning crescent Moon passes 4 degrees south of Neptune.
Solar System Data Table - May 2019
|Date||Right Ascension||Declination||Mag.||App. Size||Illum. (%)||Dist. (AU)||Constellation|
|Sun||May 01||02h 30m 43.1s||14d 50m 26.1s||-26.7||31.8'||100||1.007||Aries|
|Sun||May 15||03h 25m 01.9s||18d 40m 52.8s||-26.7||31.6'||100||1.011||Taurus|
|Sun||May 31||04h 29m 17.4s||21d 48m 01.6s||-26.7||31.6'||100||1.014||Taurus|
|Mercury||May 01||01h 16m 19.0s||05d 22m 29.4s||-0.4||5.9"||75||1.149||Pisces|
|Mercury||May 15||02h 54m 41.1s||15d 49m 34.6s||-1.4||5.2"||96||1.304||Aries|
|Mercury||May 31||05h 17m 06.5s||24d 46m 22.9s||-1.2||5.4"||89||1.245||Taurus|
|Venus||May 01||00h 47m 39.6s||03d 19m 08.6s||-3.8||11.5"||88||1.445||Pisces|
|Venus||May 15||01h 51m 04.9s||09d 41m 38.0s||-3.8||11.0"||91||1.515||Pisces|
|Venus||May 31||03h 06m 27.1s||16d 07m 52.5s||-3.8||10.5"||94||1.584||Aries|
|Mars||May 01||05h 15m 47.7s||24d 07m 28.7s||1.6||4.2"||96||2.239||Taurus|
|Mars||May 15||05h 55m 38.2s||24d 33m 09.5s||1.7||4.0"||97||2.330||Taurus|
|Mars||May 31||06h 40m 53.8s||24d 15m 42.1s||1.8||3.9"||97||2.422||Gemini|
|Jupiter||May 01||17h 31m 35.3s||-22d 38m 37.2s||-2.5||43.5"||100||4.535||Ophiuchus|
|Jupiter||May 15||17h 26m 44.0s||-22d 35m 34.1s||-2.5||44.8"||100||4.399||Ophiuchus|
|Jupiter||May 31||17h 19m 02.5s||-22d 29m 55.9s||-2.6||45.8"||100||4.306||Ophiuchus|
|Saturn||May 01||19h 27m 22.4s||-21d 31m 23.7s||0.4||17.2"||100||9.667||Sagittarius|
|Saturn||May 15||19h 26m 36.5s||-21d 33m 37.9s||0.3||17.6"||100||9.459||Sagittarius|
|Saturn||May 31||19h 24m 11.6s||-21d 39m 25.8s||0.2||17.9"||100||9.259||Sagittarius|
|Uranus||May 01||02h 02m 47.5s||11d 57m 37.7s||5.9||3.4"||100||20.847||Aries|
|Uranus||May 15||02h 05m 48.5s||12d 13m 40.9s||5.9||3.4"||100||20.792||Aries|
|Uranus||May 31||02h 09m 02.0s||12d 30m 34.3s||5.9||3.4"||100||20.670||Aries|
|Neptune||May 01||23h 16m 31.2s||-05d 44m 27.3s||7.9||2.2"||100||30.542||Aquarius|
|Neptune||May 15||23h 17m 43.0s||-05d 37m 26.2s||7.9||2.3"||100||30.341||Aquarius|
|Neptune||May 31||23h 18m 39.6s||-05d 32m 09.7s||7.9||2.3"||100||30.083||Aquarius|