Astronomy conjunctions: upcoming events and how to see them

When the Moon, planets and stars come together to form a conjunction, the results can be spectacular. Find out which conjunctions to look for in the night sky.

Conjunction: what a funny-sounding word it is, yet in the field of astronomy this phenomenon can give us some wondrous night-sky sights, ranging from naked-eye views through to binoculars and even telescopic viewing.

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There are usually a few beautiful conjunctions to see in the night sky – or early morning sky for that matter – each month, and below we’ll look at some of the best coming up over the next few weeks.

For more conjunctions and stargazing advice, listen to our Star Diary podcast, which reveals what to look out for in the evening and morning skies over the coming weeks.

You can also sign up to the BBC Sky at Night Magazine newsletter for weekly updates on what to see in the night sky.

A conjunction of the moon with Venus and Jupiter, Chanthaburi, Chanthabur, Thailand, 28 November 2019. Credit: Chakarin Wattanamongkol / Getty Images
A conjunction of the moon with Venus and Jupiter, Thailand, 28 November 2019. Credit: Chakarin Wattanamongkol / Getty Images

What is a conjunction in astronomy?

Generally speaking a ‘conjunction’ is the name given to two or more celestial objects close together in the night sky.

The most commonly observed conjunctions involve the Moon, often as a crescent in the evening or morning sky, along with any of the bright planets – Venus, Mercury, Mars, Jupiter or Saturn.

Read more observing guides:

You can also see conjunctions between the Moon and bright stars or even between the planets themselves, so there is quite a range of possible combinations.

Some involve more than two objects, such as when two planets are in conjunction and are joined by the Moon.

There are also times when incredibly close conjunctions set two objects in the same telescope field of view, or in really special cases, show Venus or Mercury transit across the face of the Sun.

You may already have come across the term in astronomy guides, yet if we went by its strictest definition then some events called conjunctions would probably not qualify.

A conjunction of the Moon, Venus, Mars and Spica, Azul, Argentina. Credit: Stocktrek Images/Luis Argerich/Getty
A conjunction of the Moon, Venus, Mars and Spica, Azul, Argentina. Credit:
Stocktrek Images/Luis Argerich/Getty

To be precise: a conjunction is a line-up of at least two celestial objects in the sky relatively close together that share the same Right Ascension (RA) or ecliptic longitude in the sky.

  • RA is the equivalent of longitude on Earth but projected onto the celestial sphere
  • The ecliptic is the plane of Earth’s orbit and appears to us as the apparent path of the Sun across the sky. Ecliptic longitude is measured along the ecliptic eastwards from the spring equinox

Even within astronomy there are different meanings of the word conjunction.

  • When a planet, either outer or inner, lies on the other side of the Sun to Earth it is said to be at superior conjunction
  • When an inner planet lies between Earth and the Sun it is at inferior conjunction
Tony Titchener captured this beautiful image of a crescent Moon and Venus on 27 February 20202, before lockdown began. Tony captured it on 27 February 2020 from Seaford, Sussex, UK using a handheld Nikon Coolpix 520 bridge camera. Credit: Tony Titchener
Tony Titchener captured this beautiful image of a crescent Moon and Venus on 27 February 2020. Tony captured it on 27 February 2020 from Seaford, Sussex, UK using a handheld Nikon Coolpix 520 bridge camera. Credit: Tony Titchener

When do conjunctions occur?

Often a conjunction will occur during daytime or when the objects are below the horizon, and this is where the definition becomes more relaxed.

If the objects are very bright, such as a crescent Moon and Venus, then daylight viewing can be possible, but if the objects have set below the horizon they won’t be visible.

So conjunction can be applied in quite a loose context to refer to objects that are viewable above the horizon in twilight or at night, even if they are not, at that point, at the exact moment of conjunction.

  • If the objects are at their closest, then this is known as an appulse: the minimum separation between two bodies that occurs just before or after true conjunction.

Conjunctions really capture our attention, which makes them ideal targets for public stargazing events, or for inspiring young astronomers and newcomers to look up at the night sky.

They are also easy to capture with a smartphone camera, giving more people the chance to preserve the moment and share with friends or on social media.

For more on this, read our guide on how to photograph a conjunction.

Moon, Venus, Jupiter & Mars Conjunction 8 Oct 2015, by Peter Louer
The Moon, Venus, Jupiter and Mars in conjunction, 8 Oct 2015. Credit: Peter Louer

Upcoming conjunctions to see in the night sky

Below we’ll look at some fascinating conjunctions coming up over the next few weeks between the Moon, planets and stars.

26, 27 September: Moon, Pleiades and Tau Tauri

On 26 September, look for the Moon in the morning sky from midnight to 4am BST, as it first lies below M45, the Pleiades star cluster, then on 27 September it lies close to Tau Tauri.

3 October: the Moon and Regulus

Look for the crescent Moon above Regulus in the morning sky around 4am onwards as northern parts of England and all of Scotland will see a near miss of Eta but anywhere south of that will see an occultation of the star by the northern part of the Moon. Binoculars or better still, a telescope, will be very useful for this.

8 October: Draconid meteor shower

Tonight the Draconid meteor shower is at its peak and with the Moon a crescent setting early on, as the radiant is circumpolar then meteors may be spotted through the night. Zenithal hourly rate is low at 5 meteors, but outbursts are known to occur for this shower so it’s definitely worth keeping a look out for them.

9, 10 October: Venus and the Moon

An illustration showing a view of Venus near the Moon in the evening twilight, looking towards the southwest on 9 October 2021 around 6pm BST. Credit: Stellarium
An illustration showing a view of Venus near the Moon in the evening twilight, looking towards the southwest on 9 October 2021 around 6pm BST. Credit: Stellarium

Back to the evening twilight and we find Venus is still clinging on as we look towards the south-west about half hour after sunset. The crescent Moon lies above right of Venus on 9 October then it’s off to the left on 10 October. Meanwhile, Antares is faint against the twilight but might just be spotted with care.

10, 11 October: Uranus and Omicron Arietis

Look towards the south-east to south, high up, as Uranus will lie above Omicron Arietis (mag. +5.7) which is a tenth of a magnitude fainter than Uranus. Binoculars and small telescope will help and Uranus may appear slightly greenish in colour.

13 October: the Moon and Saturn

Time for a naked eye view in the early evening as the first quarter Moon lies to the lower right of Saturn, which can be seen on the right-hand side of Capricornus.

The next evening the Moon then forms a triangle with Saturn and Jupiter, which lies above Gamma Capricorni with Delta cap to its left. The next evening, 15 October, the Moon then lies t the lower left of Jupiter with the two stars between them.

15 October: Mercury

Mercury returns to the morning twilight, best morning apparition lasting into November. The innermost planet starts off faint, then gradually brightens reaching greatest elongation west from the Sun on 25 October when it lies 18 degrees from it.

16 October: Comet 67P

View of M35 through an 8-inch telescope, 125x magnification. Credit: Michael Vlasov
View of M35 through an 8-inch telescope, 125x magnification. Credit: Michael Vlasov

Now for a challenge: Comet 67P/ Churyumov-Gerasimenko (made famous by the European Space Agency’s Rosetta mission) is faint at mag. +10 but lies close to M35 in the morning sky, so if you have a telescope then it’s worth either viewing or photographing this conjunction for a great picture of comet and cluster in the sky together.

21 October: the Moon, Uranus and the Pleiades

Look for the Moon a day past full when it lies between Uranus and Mu Ceti in the late evening. Next evening it lies to the lower right of the Pleiades, then forms a triangle with the cluster and Aldebaran on 23 October before passing between the horns of Taurus on 24 October.

22 October: Orionid meteor shower

The Orionid meteor shower peaks this evening, although it will be washed out by light from the Moon.

28 October: the Moon, Castor and Pollux

The Moon, Castor and Pollux will appear aligned in a straight line on 28 October 2021. This illustration shows the view looking south south-east from the southwest of England at 6am BST.
The Moon, Castor and Pollux will appear aligned in a straight line on 28 October 2021. This illustration shows the view looking south-southeast from the southwest of England at 6am BST. Credit: Stellarium

We always like line-ups in the sky, and on the morning of 28 October the Moon is in a line with Castor and Pollux. Spot it with the naked eye from midnight onwards.

30, 31 October: the Moon, Eta Leonis and Regulus

If an event occurs at the start of the month there is a good chance something similar will happen again at the end of the same month. The Moon lies to the right of Eta Leonis and above right of Regulus on 30 October, then lies to the left of them the next morning. Look from around 2am onwards both mornings with the naked eye.

More conjunctions in October 2021

  • 10 October Southern Taurids Meteor shower peak (favourable but low rates)
  • 16 October Moon lies close to Tau Aquarii (evening)
  • 17 October Moon forms triangle with Neptune and Psi Aquarii (evening)
  • 26 October Moon lies to left of Mebsuta, Epsilon Geminorum (late evening)
  • 29 October Last Quarter Moon lies near Gamma Cancri and Beehive cluster (morning)

Images of astronomical conjunctions

Below is a selection of images of conjunctions captured by BBC Sky at Night Magazine readers and astrophotographers.

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For advice on imaging the night sky, read our guide to astrophotography, and don’t forget to send us your images or share them with us via Facebook, Twitter and Instagram.

Mars Jupiter Conjunction by James Robertson, Lake District, UK. Equipment: Zwo asi120mc-s, Canon zoom lens at 18mm
Mars Jupiter Conjunction by James Robertson, Lake District, UK. Equipment: Zwo asi120mc-s, Canon zoom lens at 18mm
Moon, Venus, Jupiter and Mars Conjunction 8 Oct 2015 by Peter Louer, Tenerife. Equipment: Canon 700D 18-55mm Lens
Moon, Venus, Jupiter and Mars Conjunction 8 Oct 2015 by Peter Louer, Tenerife. Equipment: Canon 700D 18-55mm Lens
Moon, Venus, Jupiter & Mars Conjunction 10 Oct 2015 by Peter Louer, Tenerife. Equipment: Canon 700D, Samyang 10mm Lens
Moon, Venus, Jupiter & Mars Conjunction 10 Oct 2015 by Peter Louer, Tenerife. Equipment: Canon 700D, Samyang 10mm Lens
Moon & Co by Jonathan, London. Equipment: Sony
Moon & Co by Jonathan, London. Equipment: Sony
Planetary Trio Conjunction Venus Jupiter Mars by Martin Marthadinata, Surabaya, E. Java, Indonesia. Equipment: Nikon D5000, 50mm lens
Planetary Trio Conjunction Venus Jupiter Mars by Martin Marthadinata, Surabaya, E. Java, Indonesia. Equipment: Nikon D5000, 50mm lens
Venus Mars and Jupiter by John Brady, W. Lancashire, UK. Equipment: Canon Powershot SX60 IS
Venus Mars and Jupiter by John Brady, W. Lancashire, UK. Equipment: Canon Powershot SX60 IS
Jupiter, Venus, Mercury by Colin Brumfitt, Moreton Beach, Wirral, Merseyside, UK. Equipment: Sony a100, tripod.
Jupiter, Venus, Mercury by Colin Brumfitt, Moreton Beach, Wirral, Merseyside, UK. Equipment: Sony a100, tripod.
Venus, Jupiter, Moon & Mercury by Richard Sass, Cloudcroft, New Mexico USA. Equipment: Nikon D-40, 18mm lens, Tripod
Venus, Jupiter, Moon & Mercury by Richard Sass, Cloudcroft, New Mexico USA. Equipment: Nikon D-40, 18mm lens, Tripod
Jupiter & Moon by Brian.M.Johnson, Hove, UK. Equipment: Canon 50D.
Jupiter & Moon by Brian.M.Johnson, Hove, UK. Equipment: Canon 50D.
Crescent Moon & Jupiter Close Conjunction by Anthony Burley, Redditch, Worcs, UK. Equipment: Skywatcher 150P, Nikon 5100
Crescent Moon & Jupiter Close Conjunction by Anthony Burley, Redditch, Worcs, UK. Equipment: Skywatcher 150P, Nikon 5100
Crescent Moon & Jupiter Close Conjunction by Anthony Burley, Redditch, Worcs, UK. Equipment: Skywatcher 150P, Nikon 5100
Crescent Moon & Jupiter Close Conjunction by Anthony Burley, Redditch, Worcs, UK. Equipment: Skywatcher 150P, Nikon 5100
The Moon and Jupiter Meet by Steve Jarvis, Churwell, Leeds, UK. Equipment: Olympus E410, Celestron 80mm Travelscope.
The Moon and Jupiter Meet by Steve Jarvis, Churwell, Leeds, UK. Equipment: Olympus E410, Celestron 80mm Travelscope.
Christmas Conjunction: Jupiter & Moon by André Gonçalves, Vieira do Minho, Braga, Portugal. Equipment: SkyWatcher 80ED, Canon 1000D
Christmas Conjunction: Jupiter & Moon by André Gonçalves, Vieira do Minho, Braga, Portugal. Equipment: SkyWatcher 80ED, Canon 1000D
Moon and Jupiter by Humberto Cecim, Brazil. Equipment: 114/1000 Reflector Greika, Fujifilm Finepix S2800 HD
Moon and Jupiter by Humberto Cecim, Brazil. Equipment: 114/1000 Reflector Greika, Fujifilm Finepix S2800 HD
Occultation of the Moon and Jupiter by Alastair Willis, Shire of Augusta, Margaret River, Western Australia. Equipment: Nexstar 8se, Olympus FE-100.
Occultation of the Moon and Jupiter by Alastair Willis, Shire of Augusta, Margaret River, Western Australia. Equipment: Nexstar 8se, Olympus FE-100.
46 Hour Old Moon and Jupiter by Brian R Bugler, Worth Matravers, Dorset, UK. Equipment: Canon 5D mk II, 70-200 f2.8L zoom lens.
46 Hour Old Moon and Jupiter by Brian R Bugler, Worth Matravers, Dorset, UK. Equipment: Canon 5D mk II, 70-200 f2.8L zoom lens.
Moon with Jupiter by Philip Pugh, Chippenham, UK. Equipment: Nikon D3200, tripod
Moon with Jupiter by Philip Pugh, Chippenham, UK. Equipment: Nikon D3200, tripod
Moon-Jupiter Conjunction by John Bell, Haversham, Milton Keynes, UK. Equipment: Canon 5D mk2, 200mm f2.8 lens.
Moon-Jupiter Conjunction by John Bell, Haversham, Milton Keynes, UK. Equipment: Canon 5D mk2, 200mm f2.8 lens.
Conjunction of Waning Moon and Jupiter by Sarah & Simon Fisher, Bromsgrove, Worcestershire, UK. Equipment: Canon 600D, 300mm
Conjunction of Waning Moon and Jupiter by Sarah & Simon Fisher, Bromsgrove, Worcestershire, UK. Equipment: Canon 600D, 300mm
Conjunction of Jupiter and Waning Moon by Sarah & Simon Fisher, Bromsgrove, Worcestershire, UK. Equipment: Canon 600D, 300mm
Conjunction of Jupiter and Waning Moon by Sarah & Simon Fisher, Bromsgrove, Worcestershire, UK. Equipment: Canon 600D, 300mm
Moon, Jupiter and Galilean Moons by Steve Brown, Stokesley, N. Yorkshire, UK. Equipment: Canon 600D, 250mm lens, tripod.
Moon, Jupiter and Galilean Moons by Steve Brown, Stokesley, N. Yorkshire, UK. Equipment: Canon 600D, 250mm lens, tripod.
Waxing Moon & Jupiter by Sarah & Simon Fisher, Bromsgrove, Worcestershire, UK. Equipment: Canon 600D, 300mm
Waxing Moon & Jupiter by Sarah & Simon Fisher, Bromsgrove, Worcestershire, UK. Equipment: Canon 600D, 300mm
Jupiter and the Moon in Conjuction by John Foster, Plymouth, UK. Equipment: Nikon D3200, Evostar 102/1000 frac, EQ3 mount.
Jupiter and the Moon in Conjuction by John Foster, Plymouth, UK. Equipment: Nikon D3200, Evostar 102/1000 frac, EQ3 mount.
Planets, Moon and More by Alfredo Balreira, Rio Tinto, Portugal. Equipment: Canon Eos 1000D, Tripod.
Planets, Moon and More by Alfredo Balreira, Rio Tinto, Portugal. Equipment: Canon Eos 1000D, Tripod.
Conjunction over Brisbane by Teale Britstra, Brisbane, Queensland, Australia. Equipment: Canon 600D, 18-55mm lens
Conjunction over Brisbane by Teale Britstra, Brisbane, Queensland, Australia. Equipment: Canon 600D, 18-55mm lens
Venus, Jupiter and the Moon by Graham Green, Brighstone, Isle of Wight. Equipment: Canon EOS 600D, Canon EF 14mm lens, Astronomik CLS CCD filter, AstroTrac.
Venus, Jupiter and the Moon by Graham Green, Brighstone, Isle of Wight. Equipment: Canon EOS 600D, Canon EF 14mm lens, Astronomik CLS CCD filter, AstroTrac.
Sunset, Jupiter, Venus and Crescent Moon by Jenny Budden, Wimborne, UK. Equipment: Nikon D200, 18-200 lens.
Sunset, Jupiter, Venus and Crescent Moon by Jenny Budden, Wimborne, UK. Equipment: Nikon D200, 18-200 lens.
The Moon Jupiter & Venus over Tenerife by Peter Louer, Tenerife. Equipment: Canon 700d, 55mm Lens
The Moon Jupiter & Venus over Tenerife by Peter Louer, Tenerife. Equipment: Canon 700d, 55mm Lens
Moon, Venus and Jupiter Rising by Steve Brown, Stokesley, N. Yorkshire, UK. Equipment: Canon 600D, 250mm lens, tripod.
Moon, Venus and Jupiter Rising by Steve Brown, Stokesley, N. Yorkshire, UK. Equipment: Canon 600D, 250mm lens, tripod.
Jupiter - Venus conjunction and Cookham Dean Church by Roger Palframan, Cookham Dean, Berkshire, UK. Equipment: Nikon D300s, 16-85mm (~40mm).
Jupiter – Venus conjunction and Cookham Dean Church by Roger Palframan, Cookham Dean, Berkshire, UK. Equipment: Nikon D300s, 16-85mm (~40mm).
Jupiter and Venus March 2012 by George Zealey, Effingham, Surrey, UK. Equipment: Sony Alpha A390, Sony 18-75mm lens.
Jupiter and Venus March 2012 by George Zealey, Effingham, Surrey, UK. Equipment: Sony Alpha A390, Sony 18-75mm lens.
Conjunction by Mohammad Reza Ghorbanzade, Babol, Iran. Equipment: Fuji Film Finepix S4000.
Conjunction by Mohammad Reza Ghorbanzade, Babol, Iran. Equipment: Fuji Film Finepix S4000.
Dawn conjunction of Venus, Jupiter and the Pleiades by Jonathan Green, North Shore, Auckland, New Zealand. Equipment: Canon 60Da, 28-80mm Canon lens.
Dawn conjunction of Venus, Jupiter and the Pleiades by Jonathan Green, North Shore, Auckland, New Zealand. Equipment: Canon 60Da, 28-80mm Canon lens.
Jupiter/Venus by Baz Pearce, Bolton, UK. Equipment: Celestron Maksutov 127SLT, SPC900 webcam, baader ir/uv cut filter, Astro Engineering 0.6x focal reducer.
Jupiter/Venus by Baz Pearce, Bolton, UK. Equipment: Celestron Maksutov 127SLT, SPC900 webcam, baader ir/uv cut filter, Astro Engineering 0.6x focal reducer.
Venus and Jupiter Conjunction by Michael LaMonaco, United States, New Jersey. Equipment: Celestron 8SE, Advanced VX mount, Canon 60Da, Skyris 445C
Venus and Jupiter Conjunction by Michael LaMonaco, United States, New Jersey. Equipment: Celestron 8SE, Advanced VX mount, Canon 60Da, Skyris 445C
Venus and Jupiter by Allan Payeras, Paraná, Brazil. Equipment: Samsung NX1000, Samsung 20-50mm.
Venus and Jupiter by Allan Payeras, Paraná, Brazil. Equipment: Samsung NX1000, Samsung 20-50mm.
The Conjunction by John Short, Whitburn, Tyne and Wear, UK. Equipment: Canon 5Dmkii, Canon 70-300L lens
The Conjunction by John Short, Whitburn, Tyne and Wear, UK. Equipment: Canon 5Dmkii, Canon 70-300L lens
Jupiter & Venus Conjunction by Peter Louer, Tenerife. Equipment: Canon 700D, 18-55mm lens.
Jupiter & Venus Conjunction by Peter Louer, Tenerife. Equipment: Canon 700D, 18-55mm lens.
Evening Star of Venus VS Jupiter by Nazam Anuar, Johor, Malaysia. Equipment: Sony A6000.
Evening Star of Venus VS Jupiter by Nazam Anuar, Johor, Malaysia. Equipment: Sony A6000.