Observing the planets in 2021, month by month

Want to find out what planets are visible in the night sky tonight? Read our month-by-month guide to locating the planets throughout 2021

Friends stargazing. Credit: EvgeniyShkolenko / Getty

Finding and observing the planets of the Solar System in the night sky isn’t as tricky as you think. You just need to know where to look.

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When a planet is in a particularly favourable position in the evening or morning sky, it will look like a bright ‘star’, the most obvious point of light visible to the naked eye.

The other thing about spotting the planets in the night sky is that they can also be found along the ecliptic, which is the imaginary line that the Sun appears to traverse in the sky over the course of a day.

A panorama showing the Milky Way (centre) and planets. Mars is bright to the left, Saturn is dimmer and bright Jupiter is right. The arcing line joining the planets defines the arc of the ecliptic. Credit: Alan Dyer / Stocktrek Images / Getty Images
A panorama showing the Milky Way (centre) and planets. Mars is bright to the left, Saturn is dimmer and bright Jupiter is right. The arcing line joining the planets defines the arc of the ecliptic. Credit: Alan Dyer / Stocktrek Images / Getty Images

Since the major planets of the Solar System orbit the Sun in about the same plane, the ecliptic also marks the path of the planets.

Is it bright, but on the wrong side of the sky to the ecliptic? Then it’s not a planet.

Once you’ve got to grips with this, all you need to know is what planets will be visible in the night each month, so you know what to look out for, and what dates they will be best placed.

This is where our guide below comes in. Use it throughout the coming 12 months to find out which planets are visible in the night sky in 2021, which are at opposition, and to keep track of any interesting upcoming conjunctions.

Check our Astronomy Advice section throughout the year for more up-to-date stargazing tips, and sign up to the BBC Sky at Night Magazine e-newsletter for lunar phases and monthly astronomy highlights delivered direct to your email inbox.

Jupiter (the bright spot in the centre) appears near Saturn (8 o'clock of Jupiter) against the backdrop of the Milky Way, Pune, India, 5 May 2019. On 21 December 2020 the two planets will appear much closer in the night sky. Credit: Pratham Gokhale/Hindustan Times via Getty Images
Jupiter (the bright spot in the centre) appears near Saturn (8 o’clock of Jupiter) against the backdrop of the Milky Way, Pune, India, 5 May 2019. Credit: Pratham Gokhale/Hindustan Times via Getty Images

Month-by-month guide to the planets in 2021

December 2020

Mercury Bright morning object at the start of December but lost soon after. Superior conjunction on 20 December, poor thereafter.

Venus Remains a prominent object in the dawn twilight all month long.

Mars Evening planet in Pisces. Dims and shrinks throughout December. Appears 11 arcseconds across on 31st.

Jupiter and Saturn will appear separated by just 6.1 arcminutes at 17:50 UT on 21 December (as viewed south-up through a telescope). Credit: Pete Lawrence
Jupiter and Saturn will appear separated by just 6.1 arcminutes at 17:50 UT on 21 December (as viewed south-up through a telescope). Credit: Pete Lawrence

Jupiter Compromised by evening twilight. Appears to make a very close pass of Saturn on 20, 21 and 22 December.

Saturn Partnered with Jupiter. Close conjunction on 20, 21 and 22 December visible 17:00 UT, low above southwest horizon.

Look out for the Great Conjunction of Jupiter and Saturn on 21 December 2020.

Uranus Remains well positioned all month. Currently in Aries, with bright Mars visible to the west.

Neptune Well placed at the start of December. Loses altitude as darkness falls by the end of the month.


January 2021

Mercury Evening planet. Greatest eastern elongation on 24 Jan when it sets 100 minutes after the Sun.

Venus Bright morning planet, the position worsening over the month. Moon nearby on 11 Jan.

Mars Dimming evening planet. Apparent size 8 arcseconds by 31 January.

Þ Jupiter, Saturn and Mercury can be seen together in a lovely set of groupings, low in the southwest approximately 40 minutes after sunset, throughout the second week of January. Credit: Pete Lawrence
Þ Jupiter, Saturn and Mercury can be seen together in a lovely set of groupings, low in the southwest approximately 40 minutes after sunset, throughout the second week of January. Credit: Pete Lawrence

Jupiter Bright evening planet lost mid-month. Solar conjunction on 28 January. Near Saturn and Mercury from 8 January.

Saturn Evening planet, near Jupiter.  Lost as it approaches solar conjunction on 24 January.

Uranus Well positioned evening planet reaching 50º altitude. Mars is 1.6º from Uranus on 20 January.

Neptune Evening binocular planet near Phi (φ) Aquarii.


February 2021

Mercury Evening planet lost from view after 5 Feb. Inferior conjunction 8 Feb, then morning return poor.

Venus Poorly placed morning planet. Venus and Jupiter are half a degree apart on 11 February.

Mars Evening planet located 3.3º south of the Pleiades at the end of the month.

Can you catch an ultra-thin Moon low above the south-southwest horizon just after sunset on 12 February? Credit: Pete Lawrence
Can you catch an ultra-thin Moon low above the south-southwest horizon just after sunset on 12 February? Credit: Pete Lawrence

Jupiter Re-emerging into morning sky. Mercury, Jupiter and Saturn appear together just before sunrise at end of month.

Saturn Close to Jupiter, re-emerging in morning. Best at end of February, 1 hour before sunrise.

Uranus Losing altitude in evening. Waxing crescent Moon nearby on 17 February.

Neptune Evening planet, affected by twilight. Lost by end of month.


March 2021

Mercury Poorly positioned morning planet reaching greatest western elongation on 6 March.

Venus Reaches superior conjunction on 26 March and is unlikely to be seen this month.

Mars Evening planet dimming to the naked eye and telescopically small. South of the Pleiades at the start of March.

Mars passes south of the Pleiades open cluster at the start of March 2021. Credit: Pete Lawrence
Mars passes south of the Pleiades open cluster at the start of March 2021. Credit: Pete Lawrence

Jupiter Morning planet, but badly positioned despite rising 70 minutes before sunrise by the end of the month.

Saturn Morning planet close to Jupiter. Badly positioned for viewing this month.

Uranus Observing window closing as the planet drifts ever closer to the evening twilight.

Neptune Neptune is in conjunction with the Sun on 10 March and not visible this month.


April 2021

Mercury Superior conjunction on 10 April, re-emerging into a good evening position. Near Venus at the end of the month.

Venus Near Mercury at the end of April, and a 1%-lit waxing crescent Moon on 12 April.

Mars No longer telescopically viable but near M35 on evenings of 26th and 27th. Moon nearby on 17th.

Mars passes 0.6º north of the fabulous M35 open cluster in Gemini on the evenings of 26 and 27 April. Credit: Pete Lawrence
Mars passes 0.6º north of the fabulous M35 open cluster in Gemini on the evenings of 26 and 27 April. Credit: Pete Lawrence

Jupiter Bright but low morning planet rising 70 minutes before sunrise. A 22%-lit waning crescent Moon lies close by on 7 April.

Saturn Morning planet in Capricornus. Poor altitude all month. A 31%-lit waning crescent Moon lies nearby on 6 April.

Uranus Evening planet. Difficult to spot between Venus and Mercury on 23 April. Solar conjunction on 30 April.

Neptune Not visible this month.


May 2021

Mercury Well positioned evening planet, setting 90 minutes after sunset on 1 May. Near the Pleiades on 3 May.

Venus Evening planet, near a thin waxing crescent Moon on 12 May. Very close to Mercury on 28 May.

Mars Mars struggles in evening twilight. A 14%-lit waxing crescent Moon lies nearby on 15 May.

Mercury and Venus appear close from 24-26 May. They’re just over a degree apart on 25 May. Credit: Pete Lawrence
Mercury and Venus appear close from 24-26 May. They’re just over a degree apart on 25 May. Credit: Pete Lawrence

Jupiter Morning planet. A 35%-lit waning crescent Moon lies close on the morning of 5 May.

Saturn Morning planet in Capricornus. The Moon pays it a visit on the mornings of 3, 4 and 31 May.

Uranus Not visible this month.

Neptune Not visible this month.


June 2021

Mercury Evening planet reaching inferior conjunction on 11 June. Re-emerges in a poor location in the morning sky.

Venus Bright evening planet setting 90 minutes after sunset. Thin waxing lunar crescents nearby on 11 and 12 June.

A number of spectacular events between Jupiter and its largest moons can be seen during June 2021. Credit: Pete Lawrence
A number of spectacular events between Jupiter and its largest moons can be seen during June 2021. Credit: Pete Lawrence

Mars Not visible against a dark sky. Evening planet near to an 11%-lit waxing Moon on 11 June.

Jupiter Bright morning planet, rising almost 5 hours before sunrise  by 30 June.

Saturn Morning planet reaching an altitude of 19º. A bright Moon  lies nearby on the evening of  28 June.

Uranus / Neptune Not visible this month.


July 2021

Mercury Morning planet rising one hour before sunrise at the start of July. Lost by the end of the month.

Venus Evening planet poorly positioned. Half a degree from Mars on 13 July.

Mars Evening planet poorly placed. Venus nearby on 13 July. Thin waxing lunar crescent near on 11 and 12 July.

Some of the interesting Jovian moon events visible during July 2021. Credit: Pete Lawrence
Some of the interesting Jovian moon events visible during July 2021. Credit: Pete Lawrence

Jupiter Rises five hours before sunrise on 1 July. The bright waning gibbous Moon is nearby on 26 July.

Saturn Well positioned morning planet approaching opposition. Rings brighten at the end of July due to the Seeliger effect.

Uranus Morning planet slowly crawling out of the Sun’s glare. Not especially well-placed during July.

Neptune Morning planet seen under dark sky conditions at the end of July, although unable to reach peak altitude.


August 2021

Mercury Evening object for much of August. A 1%-lit waxing crescent Moon sits 7º to the east on 9 August.

Venus Poorly positioned evening planet, setting an hour after the Sun. Moon nearby on 10 and 11 August.

Mars Evening planet, too low to be seen against a dark sky. 20 arcminutes from Mercury on 19 August.

An opportunity to catch two Jovian moons in transit, along with their shadows, on the evening of 22 August 2021. Credit: Pete Lawrence
An opportunity to catch two Jovian moons in transit, along with their shadows, on the evening of 22 August 2021. Credit: Pete Lawrence

Jupiter Opposition on 19 August. Full Moon  nearby on the evening of 22 August.

Saturn Opposition on 2 August, the Seeliger effect making the rings appear brighter than normal.  A nearly full Moon lies nearby on 20 August.

Uranus Improving morning planet. Almost makes it to its highest position, due south, in darkness at the end of the month.

Neptune Morning planet, managing to reach an altitude of more than 30º in darkness from the middle of the month.


September 2021

Mercury Evening planet, rapidly deteriorating throughout the month, virtually setting with the Sun on 30 September.

Venus Low evening planet, setting an hour after sunset. A thin Moon is nearby on 9 and 10 September.

Mars The Red Planet is too close to the Sun to be seen this month.

See if you can spot minor planet 2 Pallas at opposition on 11 September 2021, shining at mag. +11 in Pisces. Credit: Pete Lawrence
See if you can spot minor planet 2 Pallas at opposition on 11 September 2021, shining at mag. +11 in Pisces. Credit: Pete Lawrence

Jupiter Bright evening planet, well-placed albeit low. A bright gibbous Moon is nearby on 17 and 18 September.

Saturn Well-positioned low evening planet. Bright Moon close by on 16 and 17 September.

Uranus On the threshold of naked eye visibility in Aries, morning planet Uranus is well placed this month.

Neptune Binocular planet Neptune reaches opposition on 14 September and is visible all night.


October 2021

Mercury Poorly positioned at the start of October, returning to the morning sky for a good display from mid-month onwards.

Venus Evening planet, remains low after sunset. A 14%-lit waxing crescent Moon lies nearby on 9 October.

Mars Mars is in solar conjunction on 8 October and not visible.

A rare double transit of Ganymede and Callisto’s shadows occurs on the evening of 4 October 2021. Credit: Pete Lawrence
A rare double transit of Ganymede and Callisto’s shadows occurs on the evening of 4 October 2021. Credit: Pete Lawrence

Jupiter Evening planet, reaching greatest altitude early evening. A waxing gibbous Moon near on 14-15 Oct.

Saturn Evening planet, reaching highest altitude early evening. A waxing gibbous Moon near on 13-14 Oct.

Uranus Well-positioned morning planet, lying close to similarly bright Omicron (ο) Arietis on 13 October.

Neptune Well-placed evening planet, reaching maximum altitude of over 30º in darkness all month.


November 2021

Mercury Well-positioned morning planet at the start of November, rises two hours before sunrise. Mars lies nearby on 15 November.

Venus Bright evening planet, low and poorly positioned. Waxing crescent Moon nearby on 7 and 8 November.

Mars Morning object. Near Mercury on 10 and 11 November and 3.6 arcminutes from Zubenelgenubi (Alpha-2 (α2)  Librae) on 22 November.

November 2021 offers a perfect opportunity to locate dwarf planet Ceres as it passes through the Hyades cluster in Taurus, reaching opposition on 27 November 2021. Credit: Pete Lawrence
November 2021 offers a perfect opportunity to locate dwarf planet Ceres as it passes through the Hyades cluster in Taurus, reaching opposition on 27 November 2021. Credit: Pete Lawrence

Jupiter Evening planet. A first quarter Moon is near on 11 November.

Saturn Evening planet. A 41%-lit waxing crescent Moon is near on 10 November.

Uranus Opposition on 4 November. An almost full Moon is 1.8º south on the morning of 18 November.

Neptune Well positioned binocular planet near Phi (φ) Aquarii, reaches 30º altitude all month.


December 2021

Mercury Evening planet, poorly positioned at the start of December. Near to Venus at the end of the month.

Venus Low evening planet. Appears near Mercury at end of December and a waxing crescent Moon on 6 and 7 December.

Mars Morning planet, with thin crescent Moon nearby on 3 December. 4.6º north of Antares on 26 December.

A bright waxing gibbous Moon interferes for much, but not all, of the two nights that the peak period of the Geminid meteor shower falls on in 2021. Credit: Pete Lawrence
A bright waxing gibbous Moon interferes for much, but not all, of the two nights that the peak period of the Geminid meteor shower falls on in 2021. Credit: Pete Lawrence

Jupiter Evening planet, unable to reach its highest altitude in darkness any more. Moon close on 8 and 9 December.

Saturn Compromised by the evening twilight. Waxing crescent Moon nearby on 7 and 8 December.

Uranus Well-positioned evening planet, 25 arcminutes south-southeast of 29 Arietis on 29 December.

Neptune Well placed at the start of December, but rapidly succumbs to the evening twilight as the month progresses.

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Pete Lawrence is an experienced astronomer and a co-host of The Sky at Night.