May 2020

Welcome to SkyEye, your guide to this month's celestial events.

The Calendar

Mercury and Venus team up low in the west on 22 May in what is the evening star's last major event this year. Venus will assume the title of morning star late next month. The rings of Saturn close to their minimum tilt for 2020 early in the month. How bright will comet C/2020 F8 (SWAN) get before perihelion passage late in the month?

The phases of the Moon in May 2020

Date Body Event
1 Mercury, Uranus conjunction: 0.3° apart
4 Venus maximum declination south
Mercury superior conjunction: anti-transit
5 Mercury ascending node
Earth η Aquariid meteor shower
6 Moon perigee
Saturn maximum declination north
7 Moon full
8 Saturn minimum ring opening: 20.5°
10 Mercury perihelion
Moon descending node
11 Saturn stationary point: direct → retrograde
13 Venus stationary point: direct → retrograde
14 Moon last quarter
Jupiter stationary point: direct → retrograde
18 Moon apogee
22 Mercury, Venus conjunction: 0.9° apart
Moon new
24 Moon ascending node
27 Mercury maximum declination north
C/2020 F8 perihelion
Moon 1.7° north of the open star cluster M44 (known as Praesepe or the Beehive Cluster)
30 Moon first quarter
31 C/2019 Y4 perihelion

The Solar System

The word planet is derived from the Greek word for 'wanderer'. Unlike the background stars, planets seem to move around the sky, keeping mostly to a narrow track called the ecliptic, the path of the Sun across the stars. Dwarf planets and small solar-system bodies, including comets, are not so constrained, often moving far above or below the ecliptic.

The position of the Sun and planets at mid-month

Sun AriesTaurus

Mercury AriesTaurusGemini

Mercury closes to 1.3° of Uranus on the first day of the month but with both planets so close to the Sun, this event will not be visible. Mercury reaches superior conjunction on 4 May and actually passes behind the disk of the Sun as seen from Earth. The tiny planet reaches its second perihelion of the year on 10 May and has a close encounter with Venus in the west after sunset on 22 May. Mercury begins the month at a bright magnitude −1.7 but dims to +0.2 by June.

Venus Taurus

The evening star is appearing lower in the west every night, on its way to inferior conjunction next month. It enters retrograde motion on 13 May and appears only 0.9° north of Mercury on 22 May when both planets are near the horizon at sunset. Venus disappears in the glow of the twilit skies by the end of the month.

Earth and Moon

The η Aquariids are somewhat spoiled by moonlight early in the month. Look for these meteors in the hours before dawn. Toward the end of the month, on 27 May, the waxing crescent Moon passes 1.7° north of the open star cluster known as Praesepe or the Beehive.

Mars CapricornusAquarius

The waning crescent Moon passes less than 3° south of Mars on 15 May. The red planet is best viewed from the southern hemisphere; the ecliptic through Capricornus and Aquarius is relatively low to the southern horizon as seen from northern temperate latitudes so Mars is a more difficult object to observe from those locations. Mars continues to grow brighter and larger in telescopes as it approaches opposition (and closest approach to Earth) in October.

Jupiter Sagittarius

A superior planet enters into retrograde motion before opposition and Jupiter reaches its stationary point on 14 May. This occurs two days after the Last Quarter Moon passes 2.3° south of the planet. Jupiter continues to brighten as the month progresses, from magnitude −2.3 to −2.6. It is easily visible from southern latitudes where it rises in mid-evening. However, for observers in the northern hemisphere, it is still primarily a morning sky object.

Saturn Capricornus

At −19.9° on 6 May, this is as far north in declination as Saturn gets this year. Two days later the rings present their smallest tilt of the year, with an opening angle of 20.5°. Retrograde motion commences on 11 May and on the following day the waning gibbous Moon passes less than 3° south of the ringed planet. Like Jupiter, Saturn is best viewed from the southern hemisphere where it rises before midnight.

Uranus Aries

Uranus was at conjunction near the end of last month and is lost in the glare of the Sun at the beginning of May. It slowly emerges from the morning twilight by the end of the month.

Neptune Aquarius

A small telescope is necessary to view the most distant planet in the solar system. Neptune is difficult to observe from northern temperate latitudes as Aquarius is low to the horizon. Southern hemisphere observers have much better views as the faint planet is high in the darkening skies.

The Celestial Sphere

Constellations are patterns of stars in the sky. The International Astronomical Union recognises 88 different constellations. The brightest stars as seen from the Earth are easy to spot but do you know their proper names? With a set of binoculars you can look for fainter objects such as nebulae and galaxies and star clusters or some of the closest stars to the Sun.

Descriptions of the sky for observers in both the northern and southern hemispheres are available for the following times this month. Subtract one hour from your local time if summer (daylight savings) time is in effect.

Local Time Mid-month Northern Hemisphere Equator Southern Hemisphere
1730 hours (1830 hours summer time) 60° N 50° N 40° N 30° N 20° N 10° N 10° S 20° S 30° S 40° S
1930 hours (2030 hours summer time) 60° N 50° N 40° N 30° N 20° N 10° N 10° S 20° S 30° S 40° S
2130 hours (2230 hours summer time) 60° N 50° N 40° N 30° N 20° N 10° N 10° S 20° S 30° S 40° S
2330 hours (0030 hours summer time) 60° N 50° N 40° N 30° N 20° N 10° N 10° S 20° S 30° S 40° S
0130 hours (0230 hours summer time) 60° N 50° N 40° N 30° N 20° N 10° N 10° S 20° S 30° S 40° S
0330 hours (0430 hours summer time) 60° N 50° N 40° N 30° N 20° N 10° N 10° S 20° S 30° S 40° S
0530 hours (0630 hours summer time) 60° N 50° N 40° N 30° N 20° N 10° N 10° S 20° S 30° S 40° S