Astronomy conjunctions: upcoming events and how to see them

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.

1 – 31 December: Venus

Venus is still viewable in the evening twilight and initially looked as if it was heading for a close encounter with Saturn but instead it drops back into the brightening evening twilight moving away from the ringed planet. Jupiter and Saturn now lie in the SW evening skies whilst Mercury joins Venus for the last week of the year.

1-3 December: crescent Moon

crescent moon December 2021

Morning twilight finds the slim crescent close to Spica on 1 December, then Alpha Librae (Zuben elgenubi) on 2 December, then close to Mars as the red planet emerges into the morning sky on 3 December.

6 December: Comet Leonard & Arcturus

Comet A1 Leonard lies near to Arcturus and is best seen in the morning sky with large binoculars or a telescope and may be mag 9 possibly brightening quickly but estimates do vary.

6 & 7 December: the Moon, Venus and Saturn

A chart showing the progression of the crescent Moon and conjunctions with planets in early December 2021

The crescent Moon lies either side of Venus in the early evening twilight. On 7 December it also lies below right of Saturn.

8 & 9 December: the Moon, Venus, Jupiter and Saturn

On 8 and 9 December the thick crescent moon lies below and either side of Jupiter. On 8 December it forms a triangle with Jupiter and Saturn. That evening the Moon also lies very close to Zeta Capricorni.

16 December: the Moon & the Pleiades

The evening gibbous moon forms a triangle with M45 and Aldebaren/Hyades but also lies near to Ceres (at mag. +7.5 it might be drowned out).

17 December: the Moon & Tau Tauri

A chart showing the Moon near Ceres, the Pleiades and the Hyades, December 2021.

The Moon lies close to Tau Tauri and – from some parts of the UK – occults it. Start viewing from about 9:20pm onwards and note that Tau Tauri has a companion star that is occulted first as a bonus.

18 – 31 December: Mars

In morning twilight Mars is slowly improving visually and lies between Beta and Delta Scorpii.

Next morning it lies very close to Omega 2 sco. By 25 and 26 December, Mars lies due north of Antares. The crescent Moon forms a triangle with Mars and Antares on the last morning of the year for a finale!

25 December: planetary parade

The planets are all on parade for us from Christmas day onwards, as Mercury lies below Venus in the bright evening twilight.

We will be able to see Saturn and Jupiter, then later that evening Neptune, Uranus and finally, in the morning sky, Mars. This is a great chance to view all the planets of the solar system through the course of one night!

December Meteor showers

Traditionally the Geminid meteor shower peaks in the early hours of 14 December, so with the Moon up most of the night it is best to look for Geminids just as the Moon is setting around 3am. This allows a few hours of darkness to catch as many as you can.

In 2021 the Geminid meteor shower will be best viewed in the early hours of 13, 14 and 15 December.

The Ursid meteor shower is circumpolar and peaks on 22 December, but moonlight will wash them out.

A rarely mentioned minor shower is the Sigma Hydrids, which peak on 9 December. It has a low ZHR of just 7, but as the Moon sets early on in the evening, they may be worth looking out for. Just don’t get them confused with any early Geminids!

More conjunctions in December 2021

  • 10 December: The Moon forms a line with Psi Aquarii and Neptune (evening)
  • 14 December: Moon lies to right of Uranus (evening)
  • 18 December: Nearly Full Moon lies between the horns of Taurus (evening)
  • 20 December: Moon lies close to Mebsuta, Epsilon Geminorum (morning)
  • 20 December: Moon forms triangle with Castor and Pollux (evening)
  • 24 December: Moon lies above Regulus and occults Eta Leonis (morning)
  • 26 December: Moon lies close to Nu Virginis (morning)
  • 27 December: Last Quarter Moon forms triangle with Zaniah and Porrima (morning)
  • 28 December: Moon lies above Spica (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.
Mars and the Moon by Steve Brown, Stokesley, N. Yorkshire, UK. Equipment: Canon 600D.
Mars and the Moon by Steve Brown, Stokesley, N. Yorkshire, UK. Equipment: Canon 600D.
Moon, Venus and Mars by Sarah & Simon Fisher, Bromsgrove, Worcestershire, UK. Equipment: Canon 600D
Moon, Venus and Mars by Sarah & Simon Fisher, Bromsgrove, Worcestershire, UK. Equipment: Canon 600D