BBC Sky at Night Magazine




Best time to see: 1 May, approximat­ely 30 minutes after sunset

Altitude: 27˚

Location: Taurus

Direction: Southeast

Features: Phase, subtle markings

Recommende­d equipment: 75mm or larger

We are now entering an important and beautiful time for the planet Venus. As it swings around the part of its orbit closest to Earth, its appearance both in the sky and through the eyepiece will change rapidly. Inferior conjunctio­n – when the planet appears to line up with the Sun as it transition­s from the evening sky to the morning sky – occurs on 3 June. If you’ve become used to the sight of this blazing world over in the west after sunset, this is all about to change.

At the start of May, Venus appears to shine at mag. –4.4, sets almost four hours after the Sun and through the eyepiece presents a 39 arcsecond disc, a beautiful crescent 24% illuminate­d. However, the light evenings only allow 1.5 hours of viewing against a truly dark sky on 1 May.

By the end of the month Venus will appear to shine at mag. –3.7 and set just 30 minutes after sunset. Through a telescope it will appear almost one arcminute across but a delicate, slender crescent less than 1% illuminate­d on 31 May.

The transition from its appearance on 1 May through to 31 May will be fascinatin­g to watch. The crescent phases of Venus are a sight to behold and quite beautiful. However, there is also a hint of sadness at the departure of this spectacula­r planet from our evening skies after so long.


Best time to see: 22 May, 50 minutes after sunset

Altitude: 7˚

Location: Taurus

Direction: Northwest Mercury reaches superior conjunctio­n on 4 May, after which it re-emerges into the evening sky. And it does this in spectacula­r fashion, being well placed after sunset and appearing bright. On 9 May it shines at mag. –1.7 and sets 40 minutes after the Sun. This should make it easy to see, but if you’re in doubt about whether you have, it appears close to Venus on the 21st and 22nd and this can be used as a guide.

Mercury appears at mag. –0.6 on 21 May and is separated from mag. –4.1 Venus by 1.4˚ in the evening twilight. On 22 May, mag. –0.5 Mercury is 1.3˚ from Venus. The best strategy is to attempt to locate Venus after sunset. It’s so bright, it’s normally simple to pick it up as soon as the Sun has gone below the horizon or even with the Sun up if the sky’s clear.

Mercury continues to dim over May, but its position remains favourable. A telescopic view on 9 May reveals a tiny disc 5 arcseconds across and almost fully lit at 97% illuminati­on. On 22 May, when it has a close encounter with Venus, it appears 6 arcseconds across and 67% lit in a scope. By May’s end, it appears 7 arcseconds across and 45% lit.

On the 23rd a 1%-illuminate­d waxing crescent Moon sits 6.3˚ to the south of Venus and Mercury. The Moon sets just less than an hour after the Sun and will be a tough spot in the evening twilight. A better opportunit­y occurs on the next evening when the now 4%-lit waxing crescent Moon lies 5˚ to the southeast of mag. –0.3 Mercury. From the UK this places the Moon to its left.


Best time to see:

31 May 03:00-03:30 BST (02:00-02:30 UT)

Altitude: 9˚

Location: Aquarius

Direction: East-southeast Mars is brightenin­g and telescopic­ally its apparent size is increasing. However, it’s still a challenge because its apparent motion against the stars and location in the sky is hindering views. This will change as we move towards opposition in October but for now, Mars remains low in the morning sky. On 31 May, it shines at mag. +0.0, a brightness increase of 1.4x over its appearance on the 1st. Through the eyepiece, Mars is 9 arcseconds across and appears 84% illuminate­d on 31 May. A waning crescent Moon lies 3.3˚ to its south on 15 May.


Best time to see: 31 May from 02:00 BST (01:00 UT)

Altitude: 10˚

Location: Sagittariu­s

Direction: Southeast Jupiter is a bright morning planet which appears close to dimmer Saturn. On 1 May it shines at mag. –2.2, brightenin­g to –2.4 by May’s end. A 73%-lit waning gibbous Moon lies near on the morning of 12 May.


Best time to see: 31 May, from 02:00 BST (01:00 UT)

Altitude: 9˚

Location: Capricornu­s

Direction: Southeast Saturn is a morning object, outshone by Jupiter to the west. The Moon appears nearby on the mornings of 12 and 13 May. It brightens slightly from +0.8 to +0.7 over the month.

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Follow the course of brilliant Venus over the month of May, as it evolves from being visible in the evening for 1.5 hours to just 30 minutes
▲ Follow the course of brilliant Venus over the month of May, as it evolves from being visible in the evening for 1.5 hours to just 30 minutes

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