In April 2021, Venus will slowly re-emerge into the evening twilight as an ‘Evening Star’, just as it did for much of 2019 and 2020.
On 12 April, Venus sits 3.7˚ northwest of a less than 1%-lit thin Moon which, at just 7.8˚ from the Sun, itself may be a tricky spot.
Things improve as we head towards the end of April, Venus’s brightness helping the planet stand out so that it can confidently be seen against the evening twilight. Currently Venus shines at mag. –3.8.
For more tips on what to see in the night sky, listen to our monthly Star Diary podcast.
And don’t forget: April also sees the return of the Lyrid meteor shower.
On 25 April Venus lies 1.1˚ south of mag. –1.5 Mercury, Venus setting 40 minutes after the Sun on this date (more on this below). By the time the end of the month arrives, Venus sets 50 minutes after the Sun.
We had a spectacular evening apparition of Venus in 2020 when the planet was able to reach a high altitude and it was well separated from the Sun.
This year’s appearance won’t be so favourable, the timing keeping Venus rather low to the horizon as it separates from the Sun. Despite this, there are still many things to look forward to.
Meetings of Venus and the waxing crescent Moon are an amazing sight to behold, and 2021 presents numerous opportunities to see these.
For more events like this, read our regularly-updated guide to upcoming astronomical conjunctions.
Although the meeting of the pair on 12 April may be tricky to catch, the one on 13 May will be a little easier. The evenings of 11 and 12 June will present a fabulous opportunity to see the thin lunar crescent near Venus, dates which repeat in July.
Things start getting tricky as we head into August, as Venus will be slipping further south in the sky and its time above the horizon after sunset will be short.
A lovely, albeit low, meeting between the thin waxing crescent Moon and Venus occurs on the evenings of 10 and 11 August, repeated on 9 and 10 September.
When to see Venus in April 2021
- Best time to see 30 April, from 20 minutes after sunset
- Altitude 3.5˚ (very low)
- Location Aries
- Direction West-northwest
- Features Phase, subtle cloud shadings
- Recommended equipment Binoculars
See a Mercury Venus conjunction in April
Mercury and Venus have a close encounter on 25 April. Venus was in superior conjunction on 25 March and is now emerging into the evening sky.
Its separation from the Sun isn’t great in April, but the steep angle the ecliptic plane makes with the western horizon at sunset during spring helps keep Venus above the horizon after sunset.
On 25 April, Venus and Mercury appear separated by just 1.2˚ after the Sun has set. They remain above the west-northwest horizon for around 45 minutes after the Sun.
Venus will be shining at mag. –3.8, Mercury at mag. –1.5, both capable of punching through the bright twilight sky. We’d recommend waiting for the Sun to properly set, then using binoculars to first locate Venus.
It shouldn’t be long before Mercury too pops out of the bright twilight sky.
While Venus takes a while to crawl away from the Sun, Mercury appears to move much faster and over the following nights the Solar System’s innermost planet zips away from Venus, climbing higher in the sky.
It retains a decent brightness too, staying brighter than mag. –1.0 for the rest of the month. It’s a great opportunity to try and spot Mercury if you’ve never seen it before.
For more on what these mag. numbers mean, read our guide to stellar magnitudes.
More planets to spot in April 2021
- Best time to see 30 April, from 30 minutes after sunset
- Altitude 6˚ (low)
- Location Aries
- Direction West-northwest
April starts with Mercury in a poor position in the morning sky. Edging closer towards the Sun, Mercury reaches superior conjunction on 19 April, marking its transition from a morning to an evening planet. To find out exactly what this means, read our guide to inferior and superior planets.
Fortunately, things improve greatly for its evening appearance, Mercury rapidly increasing in elevation after sunset towards April’s end. On 25 April, the mag. –1.5 planet sits 1.2˚ north-northwest of mag. –3.8 Venus. Both planets remain close for the rest of April. On 30 April, Mercury shines at mag. –1.1 and sets 85 minutes after the Sun.
- Best time to see 1 April, 21:00 BST (20:00 UT)
- Altitude 42˚
- Location Taurus
- Direction West
Mars is now well past its best for the current apparition, with its brightness dropping from mag. +1.3 to mag. +1.5 over the month and its apparent size dropping from and 5.3 to 4.7 arcseconds. It’s also getting lower as darkness falls. Its rapid apparent eastward motion will keep it visible for a while longer but with such a small apparent disc size it’ll be tricky to get any serious detail from the planet via a scope.
A 26%-lit waxing crescent Moon sits 3.5˚ east of Mars on 17 April. On 26 and 27 April, Mars lies 0.5˚ north of the open cluster M35 in Gemini.
- Best time to see 30 April, from 04:30 BST (03:30 UT)
- Altitude 5˚ (very low)
- Location Aquarius
- Direction East-southeast
Jupiter is a morning planet, rising 70 minutes before the Sun at the month’s start, but it’s poorly placed so it doesn’t achieve much of an altitude.
A 22%-lit waning crescent Moon sits 5.7˚ south of Jupiter on the morning of 7 April. At the month’s end, Jupiter
still rises 70 minutes before the Sun, reaching a peak altitude of 14˚ before sunrise. Next month, Jupiter has an equinox. Although the planet’s small axial tilt of 3.1˚ doesn’t cause dramatic seasonal variations in its atmosphere, around an equinox we do get to see some interesting mutual events between the four Galilean moons.
- Best time to see 30 April, from 04:00 BST (03:00 UT)
- Altitude 5˚ (low)
- Location Capricornus
- Direction Southeast
Saturn is a morning object, distancing itself from the Sun. It sits in the constellation of Capricornus, appearing like a mag. +0.7 yellowish star. A 31%-lit waning crescent Moon sits beneath it on the morning of 6 April, with Jupiter 12˚ to the east-northeast. At April’s end, Saturn manages to attain an altitude of around 13˚ before it’s lost in dawn twilight.
Uranus is not visible this month, which is a pity as on 23 April it sits between mag. –3.8 Venus and mag. –1.7 Mercury. Uranus is in conjunction with the Sun on 30 April.
Neptune is not visible this month.
Pete Lawrence is an experienced astronomer and a co-host of The Sky at Night. This guide originally appeared in the April 2021 issue of BBC Sky at Night Magazine.