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Venus Conjunctions with other Planets, 2021

Moon near Venus Dates, June 2020 to February 2021

The Venus Evening Apparition of 2019-20

Star map showing the path of Venus through the zodiac during the 2020-21 morning apparition (Copyright Martin J Powell, 2020)

The path of Venus through the zodiac constellations during the planet's morning apparition in 2020-21 (move your cursor over the image - or click on it - to reveal the constellation names in their abbreviated three-letter form - the full names are listed here). Tick-marks indicate the first day of each month. Zodiac constellations are labelled in green and non-zodiac constellations in grey. The numbers along the sides of the chart (Right Ascension and Declination) are co-ordinates of celestial longitude and latitude which are used to locate the position of celestial bodies in the night sky. A print-friendly version is available here.

The Venus Morning Apparition of 2020-21

by Martin J. Powell

Having passed through inferior conjunction on June 3rd 2020 (when it was positioned directly between the Earth and the Sun), Venus swiftly enters the dawn sky as a 'Morning Star' in mid-June. Equatorial and Southern latitudes are the first to see it, low down in the ENE shortly before sunrise. Northern latitudes begin to detect the planet from around mid-June (at 30 North), late June (50 North) and early July (60 North). At the commencement of the apparitionVenus rises in twilight across the inhabited world, not attaining any significant altitude (angle above the local horizon) before disappearing from view in the brightening sky. The planet is moving retrograde (East to West) towards the ESE against the background stars at this time, positioned just to the North of the Hyades star cluster, a distinct 'V'-shaped grouping of stars forming the head of Taurus, the Bull.

A crescent Venus sketched by Frank McCabe in March 2009 (Image: Frank McCabe/ASOD)

Planet Venus near to the Sun sketched by Frank McCabe during the planet's morning apparition on March 21st 2009. McCabe used a 4-inch (1080mm) Newtonian reflector telescope at 107x magnification (Image: Frank McCabe / ASOD)

2 0 2 0  June

Orbitally, Venus is now positioned at a relatively close 0.2724 Astronomical Units (AU) from the Earth (40.7 million kms or 25.3 million statute miles). During June the planet's solar elongation (angular distance from the Sun) increases rapidly from 10 West on June 10th to 20 West only one week later. As it emerges from the dawn twilight, telescopes pointed towards the planet show a large, slender, Eastward-facing crescent, around 5% illuminated (phase = 0.05). The planet's apparent diameter measures 56" (56 arcseconds, where 1 arcsecond = 1/60th of an arcminute or 1/3600th of a degree) and it shines at an apparent magnitude of -3.9. The crescent appears greatly disturbed by turbulence in the Earth's atmosphere, being split into the rainbow colours by an effect called dispersion (an example of how dispersion appears through a telescope can be seen here, along with other phases of the planet). Venus' large apparent diameter also means that the crescent can be glimpsed in the twilight by observers using binoculars, its apparently tiny crescent facing down towards the horizon. The planet's apparent diameter will shrink throughout the morning apparition, as it slowly recedes from the Earth in space.

Whilst Venus is pulling away from the Sun, dedicated telescopic observers begin their search for the elusive Ashen Light, which is a faint glowing of the night side of Venus through its thick clouds. The phenomenon is believed to be caused either by the planet's surface glowing red hot (due to its extremely high surface temperature) or due to electrical activity in its dense atmosphere. Observers searching for the Light will normally use ultraviolet and/or infrared filters in order to help reveal it, an occulting bar often being used to block the bright, visually-intrusive crescent from view. Observers in Equatorial and Southern hemisphere latitudes are best placed to view the Light at this early stage of the apparition due to the higher altitude of Venus above the horizon before sunrise.

Moving retrograde, Venus passes 2 North of the star Secunda Hyadum (Greek lower-case letter 'delta'1 Tau or Delta-1 Tauri, mag. +3.7) on June 14th. It is a triple star system positioned about half-way along the Northern arm of the Hyades cluster. Before the International Astronomical Union (IAU) standardized the name in 2017, the star was also known as Secundus Hyadum or Hyadum II. At the apex of the Hyades' 'V-shape' is the star Prima Hyadum (Greek lower-case letter 'gamma' Tau or Gamma Tauri, mag. +3.6) which, before IAU standardization, was known variously as Primus Hyadum or Hyadum I. Venus passes 3.3 North of the star on June 17th.

At around 0830 UT on June 19th, observers located in extreme North-eastern Canada and USA (Maine) are able to observe the 27-day-old waning crescent Moon passing in front of Venus, blocking it from view, in an event known as a lunar occultation. The event takes place in twilight just after local Moonrise; it is one of two lunar occultations which take place during the planet's 2020-21 morning apparition. Details of their timings and tracks of visibility can be seen by following the link in the Moon near Venus Dates section below.

From around mid-June Venus' motion turns more Southward against the background stars as it skirts the Northern arm of the Hyades, its daily apparent motion slowing with each passing day. On June 24th the planet's Eastward motion ceases as it reaches its Western stationary point, positioned a couple of degrees to the West of the cluster. Thereafter, the planet begins direct motion (West to East) which it will continue through to the end of the apparition. Venus reaches a solar elongation of 30 West on June 26th.

2 0 2 0  July

Venus enters the Hyades through its Northern arm on July 4th, passing 22' (0.3) South of the aforementioned Secunda Hyadum on July 5th.

Venus attains its greatest brilliancy for this apparition (mag. -4.5) on July 8th, positioned in the cental Hyades, about 2 to the WNW of Taurus' brightest star Aldebaran (Greek lower-case symbol 'Alpha' Tau or Alpha Tauri, mag. +0.9). The planet's greatest brilliancy occurs when the percentage of the illuminated portion of the disk (phase) and its angular size combine to best visual effect. In the 2020-21 morning apparition this takes place when the planet is 25% illuminated (phase = 0.25), its apparent diameter is 38".5 and its solar elongation is 38 West of the Sun.

Also on July 8th, Venus passes 1.4 North of the star Chamukuy (Greek lower-case letter 'theta'2 Tau or Theta-2 Tauri, mag. +3.7), the brightest of the Hyades' 'true' members (see Aldebaran below), positioned about half-way along the Southern arm of the cluster. The name Chamukuy was approved by the Working Group on Star Names (WGSN), a new division of the IAU, in June 2017. Since 2016 the WGSN has been cataloguing and standardizing the star names used by the international astronomical community. In the process, its has tried to accommodate the astronomical lore of a wider diversity of global cultures, i.e. from mythologies other than Arab, Greek and Roman, whose star names dominate the night sky. Chamukuy is the name of a small bird in Yucatec Mayan culture and it forms a naked-eye yellow-white double with  Greek lower-case letter 'theta'1 Tau (Theta-1 Tauri, mag. +3.8), positioned some 337" (5'.6 or 0.09) to the North. At the same moment that Venus passes Chamukuy, it also passes 1.8 South of the star Ain (Greek lower-case letter 'epsilon' Tau or Epsilon Tauri, mag. +3.5), which marks the base of the Bull's Northern horn. An exoplanet (a planet orbiting a star which is outside our Solar System) was detected orbiting Ain in 2007, which was given the designation Epsilon Tauri b.

Venus passes by several other 'newly-named' stars during its 2020-21 morning apparition, each of which will be discussed below, along with many better-known star names (proper names) for which the IAU have now introduced standardized spellings.

Crescent Venus imaged by John Boudreau of Saugus, MA, USA in December 2018 (Image: John Boudreau/ALPO-Japan)

Venus at 40% Phase imaged by John Boudreau (Saugus, MA, USA) on December 20th 2018 using a 14-inch (368mm) Dall-Kirkham telescope fitted with a CMOS camera (Image: John Boudreau / ALPO-Japan)

Venus passes 1 to the North of Aldebaran on July 12th, an orange-red star which marks the 'eye' of the Bull. Its coloration derives from the fact that it is a red giant star. Most of the Hyades stars comprise a genuine cluster, moving through space together, however Aldebaran is not part of the group; it is a foreground star, positioned at a much closer distance of 68 light years (where 1 light year = 63,240 AU) from Earth. Aldebaran is currently the brightest star in the night sky which is known to host an exoplanet. Confirmed in 2015, it is known as Aldebaran b and is estimated to have a minimum mass of about six Jupiter masses.

Around mid-July, observers at mid-Southern latitudes see Venus attain its highest altitude in the sky before sunrise for the 2020-21 apparition. At 35 South latitude, the planet rises around 3 hours ahead of the Sun and reaches an altitude of around 26 high at 30 minutes before sunrise. From the Equator (latitude 0) the planet also rises 3 hours ahead of the Sun, but reaches an altitude of 33 in the ENE at one half-hour before sunrise. From the Northern hemisphere the altitudes attained by Venus at one half-hour before sunrise are considerably lower and the visibility durations are less: at 30 North the planet rises 2 hours ahead of the Sun, reaching an altitude of 28 in the East; at 50 North the planet rises 2 hours before sunrise, reaching 18 high in the East and at 60 North it rises 2 hours before sunrise, reaching just 10 high in the ENE.

In mid-July Venus is joined in the dawn sky by the planet Mercury (mag. +2.3), now commencing its second morning apparition of 2020 and its fourth of the year overall (including evening apparitions). It is one of two paired apparitions between Venus and Mercury which take place during the 2020-21 apparition (a paired apparition being when the two planets are visible together for a prolonged period of time, either in the morning sky or the evening sky). The two planets come closest together on July 20th, when Mercury (mag. +0.6) is positioned a significant 23 to the East of Venus. Mercury itself reaches greatest Western elongation (20.1 West of the Sun) on July 22nd. The waning crescent Moon passes near the two planets between July 16th and 19th.

About half-way along the Bull's Southern horn is the unremarkable fifth-magnitude star 104 Tauri (mag. +4.9); Venus passes 7'.9 (0.13) to the South of it on July 24th at 0105 UT. Venus will occult this star on the same calendar date during its morning apparition in 2028, eight years hence (i.e. one Venus 'cycle' - for more details, see the accompanying article describing The Venus 8-year Cycle).

On July 29th Venus passes 9.4 South of the star Elnath (Greek lower-case letter 'beta' Tau or Beta Tauri, mag. +1.6), which is located at the tip of the Bull's Northern horn. The name was standardized by the IAU in 2016, previous versions of the name being spelled Al Nath, El Nath or simply Nath. The star also neatly completes the six-sided figure comprising the stars of Auriga, the Charioteer, located to the North-east of Taurus.

2 0 2 0  August

The star marking the tip of the Bull's Southern horn is Tianguan (Greek lower-case letter 'zeta' Tau or Zeta Tauri, mag. +2.9v), another 'new' name adopted by the IAU in 2017. The name Tianguan is derived from Chinese astronomy, in which it means 'Celestial Gate', an asterism within the 'Net' ('B Xi') mansion. Venus passes 1.7 South of the star on August 2nd.

During the first week of August, Mercury's second morning apparition of 2020 draws to a close as it heads into the bright dawn twilight. On August 5th, Venus enters the Northernmost section of Orion, the Hunter, which it will occupy for the next nine days. On August 6th the planet passes 12.4 North of Betelgeuse (Greek lower-case letter 'alpha' Ori or Alpha Orionis, mag. +0.7v), an orange-red variable star positioned at the North-eastern corner of the Hunter's quadrilateral. Its magnitude fluctuates between about +0.0 and +1.3 over a period of several years, which means that only on short occasions does it take the title of the brightest star in Orion - most of the time, this honour goes to Rigel (Greek lower-case letter 'beta' Ori or Beta Orionis, mag. +0.1v), positioned on the opposite corner of the quadrilateral. Venus passes through the Northern part of Orion's 'club', topped by the stars Greek lower-case letter 'chi'1 Ori and Greek lower-case letter 'chi'2 Ori (Chi-1 and Chi-2 Orionis, mags. +4.4 and +4.6), between August 6th and 8th.

The planet passes 3.3 South of the star 1 Gem (1 Geminorum, mag. +4.2), in the neighbouring constellation of Gemini, on August 9th. The star marks the foot of the Northern twin (Castor). A short distance North-east of 1 Geminorum is the open star cluster M35 (Messier 35 or NGC 2168). The cluster has an apparent diameter of 30' (about the size of the Full Moon) and it contains over 400 stars(!) It can be glimpsed with the naked-eye as a misty patch of light on a dark, clear night. Venus passes 4.3 South of the cluster on August 10th.

On August 11th Venus passes 2.5 South of the star Propus (Greek lower-case letter 'eta' Gem or Eta Geminorum, mag. +3.5v), also referred to as Tejat Prior or Praepes before IAU standardization in 2016.

Observers in Equatorial latitudes now see Venus attain its highest altitude above the local horizon for this apparition, the planet being some 37 high in the ENE at 30 minutes before sunrise. At these latitudes, the planet rises over 3 hours before sunup.

At 0127 UT on August 13th, Venus reaches its greatest elongation from the Sun for this apparition (45.8 West). Only minutes later, the planet enters Gemini, the Twins. Telescopes now show Venus' disk half-illuminated (phase = 0.50 or 50%) with an apparent diameter of 23".6. Although the greatest elongation from the Sun occurs on August 13th, Venus is in fact positioned at 45.8 elongation for a whole week from August 10th through to August 16th. The planet's apparent magnitude at this time is -4.3. When seen from a point far above the Solar System, the Earth, Venus and the Sun now form a right-angled triangle in space, with Venus positioned at the 90 angle.

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Martin J Powell is a participant in the Amazon.com, Amazon.ca, Amazon.co.jp and Amazon Europe S. r.l. Associates Programmes. These are affiliate advertising programmes designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com, Amazon.ca, Amazon.co.jp, Amazon.co.uk, Amazon.de and Amazon.fr. As an Amazon Associate, Martin J Powell earns from qualifying purchases.

In theory, greatest elongation is the time at which the planet's terminator (the line seperating the light and dark sides of the planet) appears perfectly straight through telescopes, essentially dividing Venus into two perfect halves; this is known as the dichotomy. However, telescopic observers often report the straight terminator several days earlier or later than the greatest elongation date; typically early in evening apparitions and late in morning apparitions. This is known as the phase anomaly or Schrter's Effect (after the German astronomer Johann Schrter, who first observed the phenomenon in 1793) and is thought to be due to Venus' dense atmosphere scattering the sunlight. In the current apparition, therefore, telescopic observers can expect to see a 50% phase on or around August 17th.

Contrary to what one might think, greatest elongation day is not necessarily the day on which Venus is above the horizon ahead of sunrise for the longest period of time. Since the angle of the ecliptic (the apparent path of the Sun, which the Moon and planets follow very closely) to the Eastern horizon at dawn varies with the observer's latitude, Venus is seen above the horizon for differing periods of time at different latitudes. At 60 North Venus rises 4 hours before sunrise, whilst at 45 South the planet rises only 2 hours before the Sun. At other Northern latitudes the visibility durations are as follows: 3 hours at 50 North; 3 hours at 30 North; 3 hours at the Northern Tropics and the Equator. In the Southern hemisphere the planet is above the horizon for 3 hours at 15 South and the Southern Tropics, and 2 hours at 35 and 45 South. Hence for the current apparition, observers at higher Northern latitudes are best placed to see Venus above the horizon for the longest period on greatest elongation day.

Venus at half-phase imaged by Akira Nakata in January 2019 (Image: Akira Nakata/ALPO-Japan)

Venus at Greatest Elongation in the morning sky, imaged by Akira Nakata of Kobe, Japan on January 7th 2019. Nakata used an 10-inch (25cm) Newtonian reflector telescope fitted with a CMOS camera (Image: Akira Nakata / ALPO-Japan)

At any given time before sunrise on greatest elongation day in 2020, the altitude reached by the planet is highest in the Northern Tropics. Taking a period of 30 minutes before sunrise as an example, it is 37 high at latitude 20 North. The lowest altitude attained by the planet on this day is at mid-Southern latitudes, where it is only around 17 above the horizon at one half-hour before sunrise. Even at high-Northern latitudes, where the planet is visible for much longer on this day, the altitude is not particularly high: only 23 at 60 North, for example. The reason for this is that, at high Northern latitudes, the rise/set angle is much shallower than at Equatorial or mid-Southern latitudes. Twilight also lasts longer at high-Northern latitudes during the local summer months (a consequence of the Sun's high declination and shallow rising angle), which allows the planet to be seen for a longer period. Consequently, on this occasion Venus is visible on greatest elongation for longer in the Northern hemisphere than in the Southern, despite its sub-optimal altitude above the horizon.

Greatest elongation day now having passed, the phase of Venus changes from crescentic to gibbous (i.e. between a half-disk and a full disk), as it will remain through to the end of the apparition.

Later on August 13th Venus passes 2.4 South of the star Tejat (Greek lower-case letter 'mu' Gem or Mu Geminorum, mag. +3.0v), which marks the Northern twin's knee. Before IAU standardization the star was known by several other names: Tejat Posterior, Nuhatai, Calx and Pish Pai! At 0324 UT on August 15th Venus passes 6'.8 (0.11) to the South of the double star Greek lower-case letter 'nu' Gem (Nu Geminorum, mag.+4.1), which the planet will occult on the same calendar date eight years hence, in 2028. At around 09 hours UT on the same day, the distance between the Earth and Venus is the same as that between the Sun and Venus, at 0.7260 AU (108.6 million kms or 67.4 million miles). Seen from far above the Earth's North pole, the Earth, Venus and the Sun now form an isoscelene triangle in space, with Venus positioned at the apex.

On August 17th Venus passes 3.8 North of the star Alhena (Greek lower-case letter 'gamma' Gem or Gamma Geminorum, mag. +2.0), which is positioned at the foot of the Southern twin (Pollux).

On August 18th the planet passes 4.9 South of Mebsuta (Greek lower-case letter 'epsilon' Gem or Epsilon Geminorum, mag. +3.0) which is positioned at the groin of the Northern twin. On the same day Venus attains its highest declination for this apparition, at +20 6' 26" (+20.1072 in decimal format). The planet now rises at its most Northerly point along the local horizon, an effect which is more pronounced the further North in latitude an observer is situated.  For example, at the Equator Venus rises in the ENE at this time whilst at 60 North it rises in the North-east, some 25 further North along the horizon.

By the third week of August Venus is rising in darkness across the inhabited world. At 0955 UT on August 23rd Venus passes 30' (0.5) South of the optical double star Mekbuda (Greek lower-case letter 'zeta'Gem or Zeta Geminorum, mag. +3.9v), positioned at the right knee of the Southern twin. The planet passes 2.1 South of the star Wasat (Greek lower-case letter 'delta' Gem or Delta Geminorum, mag. +3.5) on August 27th and 12.2 South of Castor (Greek lower-case letter 'alpha' Gem or Alpha Geminorum, mag. +1.6), Gemini's second-brightest star, on August 30th.

2 0 2 0  September

At the start of September, telescopes show Venus with a 60% illuminated gibbous phase, its apparent diameter having reduced below 20". To the naked-eye the planet now shines at an apparent visual magnitude of -4.2.

At around 0725 UT on September 1st, the constellation's brightest star Pollux (Greek lower-case letter 'beta' Gem or Beta Geminorum, mag. +1.1), Greek lower-case letter 'kappa' Gem (Kappa Geminorum, mag. +3.5) and Venus form a line 8.6 in length, aligned roughly celestial North and South. The line is visible just before dawn from the North-eastern tip of Canada, the North-eastern tip of the USA and the North-eastern part of South America. The angular distance between Pollux and  Greek lower-case letter 'kappa' Gem is 3.6 and that between Greek lower-case letter 'kappa' Gem and Venus is 4.9. Extending the line some 14.3 to the South of Venus brings one very close to the bright star Procyon (Greek lower-case letter 'alpha' CMi or Alpha Canis Minoris, mag. +0.5) in the constellation of Canis Minor, the Lesser Dog. Venus passes 5.0 South of Greek lower-case letter 'kappa' Gem itself at around 1240 UT that same day, and about an hour later, the planet passes 8.6 to the South of Pollux. In 2006 an exoplanet was discovered orbiting Pollux, which is 34 light years distant. Named Pollux b or Thestias (after the patronage of Leda in Greek mythology), the exoplanet is thought to have a mass equivalent to 2.3 Jupiter masses and it orbits the star at a distance of 1.6 AU in a period of 589 days. Pollux is the brightest of seven stars in Gemini which are thus far known to host an exoplanet.

From late August into early September, observers at Northern latitudes see the planet attain its highest altitude above the horizon for the 2020-21 morning apparition. At latitude 30 North, some 30 minutes before sunrise, the planet reaches 37 above the Eastern horizon. At higher latitudes the altitude attained is progressively less. From latitude 50 North, in early September, the planet is placed 33 above the Eastern horizon at 30 minutes before sunrise. From latitude 60 North, in late August, the planet is placed 31 above the ESE horizon at 30 minutes before sunrise. Two weeks after the date of greatest elongation, Northern latitudes see Venus rising 3 hours before the Sun (at 30 North), 4 hours before the Sun (at 50 North) and 4 hours before the Sun (at 60 North). At Equatorial latitudes the planet rises in the ENE 3 hours before sunrise while at 35 South the planet rises in the East about 2 hours before the Sun.

Venus enters Cancer, the Crab - the faintest of the zodiac constellations - on September 4th. At around 1640 UT on September 6th Castor, Pollux and Venus form a line some 15.2 in length, orientated SSE-NNW. The alignment is visible just before dawn from the central and North-western Pacific Ocean. The line points towards the head of Hydra, the Water Snake, positioned 16 to the SSE of Venus.

'Morning Star' Venus rising in Taurus in July 2017 (Copyright Martin J Powell 2017)

'Morning Star' Venus rising at the start of dawn twilight, photographed by the writer in July 2017. The planet was positioned in Taurus, a short distance North-east of the Hyades cluster - the V-shaped group of stars at the right of the picture (click on the thumbnail for the full-size picture).

 

Venus passes 9.2 North of Cancer's brightest star Tarf (Greek lower-case letter 'beta' Cnc or Beta Cancri, mag. +3.5) on September 8th. The star is positioned at the South-western corner of the constellation's lambda-shaped (Greek lower-case letter 'lambda') figure. The name Tarf, which is not in common usage, is derived from the Arabic Al Tarf meaning 'the End', i.e. the end of the Crab's leg. The name was approved by the IAU in June 2018.

From September 13th-14th Venus passes about 2.3 South of the open cluster called Praesepe or The Beehive Cluster (M44 or NGC 2632). Under dark, rural skies it is visible to the naked-eye as a hazy patch of light and in city locations it is easily seen in binoculars (for a fuller description of this cluster, see the Zodiacal Sky: Cancer, Leo and Virgo page). Venus takes some 19 hours to traverse the angular width of the cluster, which measures 1.5 in diameter (three times the apparent width of the Full Moon) and contains around 75 stars.

On September 14th Venus passes 1 South of Asellus Australis (Greek lower-case letter 'delta' Cnc or Delta Cancri, mag. +3.9), one of two stars which flank Praesepe on its Eastern side - the other being Asellus Borealis (Greek lower-case letter 'gamma' Cnc or Gamma Cancri, mag. +4.6), located 3.3 further North. The planet passes 4.6 North of Acubens (Greek lower-case letter 'alpha' Cnc or Alpha Cancri, mag. +4.3), at the South-eastern corner of the constellation, on September 17th.

On September 20th at around 15 hours UT Venus is positioned at precisely 1.0000 AU from the Earth, i.e. the same distance as the average distance of the Earth from the Sun (149.5 million kms or 92.9 million statute miles). At this point in the apparition the distance between Venus and the Earth is increasing at an average rate of about 1.07 million kms (667,500 statute miles) per day.

Venus enters Leo, the Lion, on September 22nd, crossing to the North of the ecliptic on September 26th. The planet passes 4.0 North of the star Subra (Greek lower-case letter 'omicron' Leo or Omicron Leonis, mag. +3.5), which marks the paw of the Lion's foreleg, on September 27th. Between September 28th and October 5th Venus is positioned South of the asterism (star pattern) commonly known as the Sickle of Leo, at the Western end of the Lion, which appears to the naked-eye as a backward question-mark (A backward question-mark). The planet passes 10 South of the star Ras Elased Australis (Greek lower-case letter 'epsilon' Leo or Epsilon Leonis, mag. +2.9), at the upper North-western end ('pointed end') of the sickle, on September 28th.

2 0 2 0  October

At the base of the Sickle of Leo (the 'dot' of the backward question-mark) is Leo's brightest star, Regulus (Greek letter Alpha Leo or Alpha Leonis, mag. +1.3). Venus passes just 5'.5 (0.1) South of the star at 2340 UT on October 2nd. Regulus is positioned less than 0.5 North of the ecliptic so it is occasionally occulted by planets and - more frequently - by the Moon. Venus last occulted Regulus in July 1959 and will next occult the star during its morning apparition in October 2044.

In early October Venus shines at magnitude -4.1, almost one half-magnitude fainter than it had shone on its greatest brilliance day three months earlier. The planet's solar elongation has reduced to 40 and its apparent diameter is around 15" - a little over one-quarter of it's apparent size at the start of the appariton. Telescopes reveal a notably gibbous phase, around 70% illuminated. With the planet now heading Southwards along the ecliptic, the position of Venus along the local horizon at dawn begins to move noticeably further Southwards with each passing week.

On October 5th Venus passes 8.8 South of the star Algieba (Greek lower-case letter 'gamma'1 Leo or Gamma-1 Leonis, mag. +2.3), at the base of the Lion's neck (although the name is Arabic for 'the forehead'). It is a double star with golden-yellow components (Greek lower-case letter 'gamma'1 Leo and Greek lower-case letter 'gamma'2 Leo) of magnitudes +2.3 and +3.6, separated by an angular distance of 4".7. The pair are about 130 light years from Earth and they orbit each other in a period of 554 years. The star is easily split in small telescopes and is considered to be one of the finest double stars in the night sky. An exoplanet was detected orbiting Algieba in 2009, named Gamma-1 Leonis b. Its mass is equivalent to 8.8 Jupiter masses and it orbits the star at a distance of 1.2 AU in a period of 428 days.

Venus passes 9.2 South of the star Chertan (Greek lower-case letter 'theta' Leo or Theta Leonis, mag. +3.3), at the top of the Lion's rear leg, on October 17th. Prior to IAU standardisation in 2016 the star was also known as Coxa or Chort. At the same moment the planet passes 14.3 South of the star Zosma (Greek lower-case letter 'delta' Leo or Delta Leonis, mag. +2.7), at the rump of the Lion. The planet passes 31' (0.5) South of the star Greek lower-case letter 'sigma' Leo (Sigma Leonis, mag. +4.0), at the foot of the Lion's hind leg, on October 19th.

At 03 hours UT on October 22nd Venus passes 16.4 to the South of the newly-named star Formosa, positioned just to the North of the Lion's rump. At magnitude +6.4, it is on the threshold of naked-eye visibility from dark sky sites. Its astronomical coordinates are RA = 11h 35m 3s and Greek lower-case letter 'delta' = +20.44 and it is also known by the designations HD 100655 and BSC4459. The name was approved by the IAU in December 2019, just one of many results of their campaign entitled NameExoWorlds, which celebrated the 100th year of the organistaion. The campaign invited participants from around the world to submit names for exoplanets and their host stars. Formosa is named after the historical name of Taiwan, in use during the 17th century; it is Latin for 'beautiful'. The exoplanet orbiting the star (HD 100655 b), discovered in 2011, is named Sazum, after the township Yuchi; it means 'water' in the language of the local Thao people.

Venus enters Virgo, the Virgin, on October 22nd, passing 0.8 North of the star Zavijava (Greek lower-case letter 'beta' Vir or Beta Virginis, mag. +3.6), at the back of the Maiden's head, on October 25th. Before IAU standardization in 2016 the star was also known by the names Zavijah, Zavyava or Alaraph.

Venus passes through perihelion (its closest orbital point to the Sun) on October 30th, when it is 107.4 million kms (66.7 million miles) from the Sun. The planet crosses to the South of the celestial equator (Greek lower-case letter 'delta' = 0) on the following day (October 31st), meaning that the planet now rises due East across the inhabited world.

2 0 2 0  November

On November 1st Venus passes 16' (0.26) North of the star Zaniah (Greek lower-case letter 'eta' Vir or Eta Virginis, mag. +3.8), which is positioned at the rear of the Maiden's head.

In early November, Venus, now magnitude -4.0, is again joined in the dawn sky by the planet Mercury (mag. +1.0) in the second paired apparition between the two planets during Venus' 2020-21 morning apparition. Owing to the steep angle of the ecliptic to the Eastern horizon at dawn at this time of year, this apparition favours Northern hemisphere observers.

On November 4th, Venus passes 3.7 North of the star 25 Virginis (mag. +5.8), another star which the planet will occult at a future date - in this case, during its evening apparition in 2026. On November 5th the planet passes 5.6 North of the star Greek lower-case letter 'chi' Vir (Chi Virginis, mag. +4.6), which was found to have an exoplanet in 2009. Named Chi Virginis b, the planet is thought to have a mass equivalent to 11 Jupiter masses and orbits Chi Virginis at a distance of 2.1 AU in a period of 835 days. Chi Virginis is the brightest Virgoan star currently known to have exoplanets.

An infra-red image of gibbous Venus imaged by Martin R Lewis of St Albans, UK in April 2019 (Image: Martin R Lewis/ALPO-Japan)

Gibbous Venus  An infra-red image taken 'in poorish seeing' by Martin R Lewis of St Albans, England, UK on April 20th 2019. Lewis used an 8-inch (222mm) Dobsonian telescope fitted with a CMOS camera (Image: Martin R Lewis / ALPO-Japan)

On November 6th Venus passes 1.2 South of the star Porrima (Greek lower-case letter 'gamma' Vir or Gamma Virginis, mag. +2.8), named after one of the Roman goddesses of prophecy. It is a binary star comprising components of magnitude +3.4 and +3.5, appearing to the naked-eye as a single star of magnitude +2.9. The pair orbit each other in a period of 169 years, their separation varying greatly throughout. They came closest together around 2006, when they were just 0".4 apart, making them difficult to separate in anything but the largest of telescopes. Currently 2".9 apart, the pair are widening and are becoming easier to separate in amateur telescopes, aligned North-South in relation to each other. Before IAU standardization in 2016 Porrima was also known as Arich (a name whose origin appears to be shrouded in mystery) or Postvarta, which appears to have been a variation of Postverta (or Postvorta), the Roman goddess of childbirth and the past.

Mercury reaches greatest elongation on November 10th, when it is 19.1 West of the Sun. It now shines at magnitude -0.5 and is positioned 13.2 to the ESE of Venus. The waning crescent Moon passes by the two planets over a three-day period commencing November 12th.

At 0541 UT on November 12th Venus passes just 1'.5 (0.02) North of the double star Greek lower-case letter 'theta' Vir (Theta Virginis, mag. +4.4), located at the base of the Maiden's neck. The planet will occult this star in November 2044, three Venus 'cycles' into the future. On November 14th the planet passes 12 North of the star 61 Virginis (mag. +4.7), a star which, in 2009, was found to have two - and possibly three - exoplanets. All three planets (61 Virginis b, c and d) orbit the star at a distance which would place them within the equivalent orbit of Venus in our own Solar System. The innermost planet (b) orbits the star in just 4 days and is most likely rocky (terrestrial) in nature, whilst the other two are considered more likely to be gas giants, similar in composition to Uranus and Neptune. At 28 light years distant, 61 Virginis is one of the closest stars to Earth which is known to have exoplanets.

With the crescent Moon still in the vicinty of Mercury and Venus on the 14th, the two planets come closest together for this paired apparition, Mercury (mag. -0.6) being positioned 12 to the ESE of Venus.

On November 15th Venus passes 4.1 North of Virgo's brightest star Spica (Greek lower-case letter 'alpha' Vir or Alpha Virginis, mag. +1.0), a blue-white star which dominates the South-eastern region of the constellation. On November 20th Venus passes 8.0 North of 89 Virginis (mag. +4.9), which the planet will occult during its evening apparition in 2042.

From the third week of November, Mercury heads out of view from the dawn sky, leaving Venus as the only major planet now visible in the morning sky. Venus passes 1.3 South of the star Kang (Greek lower-case letter 'kappa' Vir or Kappa Virginis, mag. +4.2) on November 25th. In Chinese astronomy Kang was both a constellation and a name given to the second lunar mansion. The name was formerly approved by the IAU in 2017.

Venus leaves Virgo and enters Libra, the Balance (or Scales), on November 27th.

2 0 2 0  December

On December 3rd Venus passes 1.3 North of the double star Zubenelgenubi (Greek lower-case letter 'alpha'2 Lib or Alpha2 Librae, mag. +2.8) and, on December 6th, 9.7 North of the star Brachium (Greek lower-case letter 'sigma' Lib or Sigma Librae, mag. +3.3). Telescopically Venus now appears 89% illuminated with an apparent size of 11".6. With the solar elongation having reduced below 30, the planet appears much lower in the sky than it had been a few months previous. At mid-Northern latitudes, half an hour before sunrise, Venus appears just 15 above the horizon, less than half the altitude it had been in late August. At mid-Southern latitudes, some 30 minutes before sunrise, the planet is even lower (ca. 11 high) over the ESE horizon. In the Northern hemisphere, the month of December sees Venus' altitude above the horizon fall off rapidly day-by-day as it heads in towards the Sun.

The planet passes 7.2 South of the star Zubeneschamali (Greek lower-case letter 'beta' Lib or Beta Librae, mag. +2.5), the Northernmost star of the Balance figure, on December 8th. The late astronomer Sir Patrick Moore once described Zubeneschamali as being 'the only naked-eye star which is said to have a greenish tint - though most observers will certainly class it as white!'.

At 1430 UT on December 12th, Venus passes 3 South of the star Zubenelhakrabi (Greek lower-case letter 'gamma' Lib or Gamma Librae, mag. +4.0) a name which was alternatively spelled Zuben Elakrab before IAU standardisation in 2017. It is commonly said to mean 'claw of the Scorpion' although it originates from a much earlier Sumerian name meaning 'balance of heaven'. The reference to the Scorpion derives from the fact that the ancient Greeks considered the stars in this region of the sky to be part of Scorpius, the Scorpion, before the Romans divided them into two separate constellations.

Some 6 hours after passing Zubenelhakrabi, the second of two lunar occultations of Venus' morning apparition takes place. At around 21 hours UT the 26-day old waning crescent Moon blocks the planet from view, an event which is visible in twilight just after local Moonrise from the North-eastern tip of Russia and from Northern Alaska, USA. Details of this event can be seen by following the link in the Moon near Venus Dates section below.

Venus passes 2.2 South of the star Greek lower-case letter 'theta' Lib (Theta Librae, mag. +4.1), in Eastern central Libra, on December 16th. At 0440 UT on December 17th the planet passes 6.8 North of the star Fang (Greek lower-case letter 'pi' Sco or Pi Scorpii, mag. +2.8) in the neighbouring constellation of Scorpius, the Scorpion; specifically in the head of the Scorpion. The name was formally assigned to the star by the IAU in 2017 after the fourth lunar mansion in ancient Chinese astronomy. In ancient China the four stars that we now consider to form the head of the Scorpion (Greek lower-case letter 'beta'1 Sco, Greek lower-case letter 'delta' Sco, Greek lower-case letter 'pi' Sco and Greek lower-case letter 'rho' Sco) were known as Fng (Room), the name of Greek lower-case letter 'pi' Sco in particular (Fng Xi) translating as "the First Star of Room". At 1130 UT that same day Venus passes 3.3 North of the star Dschubba (Greek lower-case letter 'delta' Sco or Delta Scorpii, mag. +2.2), also in Scorpius; the planet enters the constellation 8 hours later, at about 1950 UT.

Venus passes 10'.7 (0.18) North of the striking double star Acrab (Greek lower-case letter 'beta'1 Sco or Beta-1 Scorpii, combined mag. +2.6) at around 1030 UT on December 18th. Before IAU standardisation in 2016 the star was alternatively called Graffias, a name which is thought to refer to a crab's claws and is therefore, synonymous with those of a scorpion. The star's two blue-white components (Greek lower-case letter 'beta'1 Sco and Greek lower-case letter 'beta'2 Sco), of magnitudes +2.6 and +4.9 respectively, are separated by 13".7 and are easily seen in small telescopes. Beta-1 Scorpii is itself also double, having a tenth-magnitude companion positioned less than an arcsecond away, separable only in larger telescopes.

Later on December 18th, between 1645 UT and 1930 UT, Venus passes 1 North of the two Omegan stars Jabhat al Akrab (Greek lower-case letter 'omega'1 Sco or Omega-1 Scorpii, mag. +3.9) and Omega-2 Scorpii (Greek lower-case letter 'omega'2 Sco, mag. +4.3). Together with Dschubba, Acrab and the quadruple star named Jabbah (Greek lower-case letter 'nu' Sco or Nu Scorpii, mag. +4.0), they form a distinctive asterism in Northern Scorpius. Venus passes 30' (0.5) South of Jabbah on the following day (19th).

On December 21st Venus passes 5.2 North of the variable star named Alniyat (Greek lower-case letter 'sigma' Sco or Sigma Scorpii, mag. +2.9v). Later that same day the planet enters the non-zodiacal constellation of Ophiuchus, the Serpent-Bearer. On December 22nd, at about 1945 UT, the planet passes 7.3 South of a magnitude +6.9 star in South-eastern Ophiuchus which received a new name in late 2019. The star, which is easily seen in binoculars, is named Timir (it is also known under lengthy catalogue designations such as HD 148427, HIP 80687 or BD-13 4437). For the curious, its astronomical coordinates are: RA = 16h 28m 28s, Greek lower-case letter 'delta' = -13.39. Like the star Formosa in Leo (see above), the name was selected as a result of the IAU's NameExoWorlds campaign. Timir means 'darkness' in the Bengali language, alluding to the star being far away in the darkness of space. Timir's exoplanet (HD 148427 b) is named Tondra, which means 'nap' in Bengali, alluding to the symbolic notion that the planet was 'asleep' until it was discovered (in 2009).

Also on December 21st, on the opposite side of the Sun some 53 to the ESE of Venus, the giant planets Jupiter and Saturn pass each other in the night sky for the first time since May 2000. Visible in the dusk sky in the constellation of Capricornus, the Sea Goat, they are separated by just 0.1, which is their closest passage in almost four centuries; such an event is called a planetary conjunction. For details on the observability of this 'Great Conjunction', see the Jupiter or Saturn pages. Venus is regularly involved in planetary conjunctions, although only one of them takes place during the 2020-21 morning apparition: at the very end of the period, in February 2021.

On December 23rd Venus passes 5.7 North of Scorpius' brightest star, the orange-red Antares (Greek lower-case letter 'alpha' Sco or Alpha Scorpii, mag. +1.0v); its Latin name refers to the star's colour similarity to the planet Mars.

Over the following 12 days Venus passes to the North of five stars in Scorpius which were formally assigned 'new' names by the IAU in 2017 and 2018 (they are labelled in yellow-green on the star map here). All five are located in the tail of Scorpius and none of them can be seen from latitudes North of 55 North since they never rise above the horizon from these latitudes. On December 24th Venus passes 7.2 North of the star Paikauhale (Greek lower-case letter 'tau' Sco or Tau Scorpii, mag. +2.8), a name which is Hawaii'an for a vagabond. On December 26th the planet passes 12.7 North of the star Larawag (Greek lower-case letter 'epsilon' Sco or Epsilon Scorpii, mag. +2.2), positioned about half-way along the Scorpion's tail, which is an Aboriginal name from the Wardaman culture of Northern Australia.

On December 27th Venus passes 16.2 North of the stars Xamidimura (Greek lower-case letter 'mu'1 Sco or Mu-1 Scorpii, mag. +2.9) and Pipirima (Greek lower-case letter 'mu'2 Sco or Mu-2 Scorpii, mag. +3.5), which are located 3.5 South of Larawag. The two stars are separated in the night sky by just 5'.7 (0.1), making them appear as a double star, however this is a line-of-sight effect and they are not physically related. Xamidimura is an eclipsing binary of the Beta Lyrae variable star type whilst Pipirima is a blue-white subgiant star. Xamidimura is the historical name given to the star by the Khoikhoi people of South Africa; it means 'eyes of the lion'. The name Pipirima comes from Polynesian mythology. It refers to a Tahitian story of two inseparable twins (Pipirima and Rhua) who fled from their parents and became stars in the night sky.

On December 30th Venus passes 6.4 South of the star Sabik (Greek lower-case letter 'eta' Oph or Eta Ophiuchi, mag. +2.5), the second brightest star in Ophiuchus. The name is Arabic and translates as 'the preceding one'. On December 31st the planet passes 4.3 North of the star Guniibuu (36 Oph A or 36 Ophiuchi A, mag. +5.1), another star assigned a 'new' name by the IAU in this region of the night sky. It is an Australian Aboriginal name meaning a robin red-breast, derived from Euahlayi-Kamilaroi culture. Guniibuu is one component of a pair of orange dwarf stars (A and B) which are easily split in small telescopes.

2 0 2 1  January

With the arrival of the new year, observers at high-Northern latitudes begin to have difficulty detecting Venus, which is now rising in twilight just 1 hours ahead of sunrise, the planet's solar elongation having reduced to 20. The planet has also faded slightly further to magnitude -3.9. In the Southern hemisphere, the planet's altitude above the horizon at any given duration before sunrise will fall away quickly during January.

On January 1st Venus passes 2.5 North of Ophiuchus' Southernmost bright star Greek lower-case letter 'theta' Oph (Theta Ophiuchi, mag. +3.2). On older star maps the stars Greek lower-case letter 'theta' Oph and Guniibuu were depicted as marking the ankle of the Serpent-Bearer.

To the South of Ophiuchus the Scorpion's tail curves around to the East and North-east, deep within an area rich in Milky Way galaxy stars. Venus passes 14.7 North of the star Lesath (Greek lower-case letter 'upsilon' Sco or Upsilon Scorpii, mag. +2.6) on January 3rd and 14.4 North of the star Shaula (Greek lower-case letter 'lambda' Sco or Lambda Scorpii, mag. +1.6) on January 14th. Together these two stars form the 'sting' at the end of the Scorpion's tail.

On January 4th Venus passes 7.4 South of the star Greek lower-case letter 'xi' Ser (Xi Serpentis, mag. +3.5), positioned 6.5 to the East of the aforementioned Ophiuchan star Sabik and at the South-eastern corner of a trapezoidal arrangement of third and fourth-magnitude stars. Located in the constellation of Serpens Cauda, the Serpent's Tail, the other two stars are Greek lower-case letter 'omicron' Ser (Omicron Serpentis, mag. +4.2) at the North-eastern corner of the trapezoid and Greek lower-case letter 'nu' Ser (Nu Serpentis, mag. +4.3) at the North-western corner. This is, of course, the tail section of the serpent, which the Serpent-Bearer is holding. Venus leaves Ophiuchus and enters the Southernmost zodiac constellation of Sagittarius, the Archer, on January 5th.

On January 7th Venus passes 14.1 North of the fifth star in Scorpius' tail to be assigned a 'new' formal name by the IAU. Fuyue (G Scorpii, mag. +3.2) is positioned at the tail-end of the Scorpion. Fu Yue was a Chinese labourer who became a wise minister and a chancellor of the Emperor Wu Ding (ca. 1250-1192 BC) of the Shang dynasty. After Fu Yue's death he is said to have become part of a constellation known as The Sieve, situated in the Tail mansion (Wei Xi) in ancient Chinese astronomy.

On January 12th Venus attains its most Southerly declination for this apparition at -23 10' 44" (-23.179 in decimal format). Across the world, the planet now rises at its most Southerly point along the local Eastern horizon. This will typically be towards the South-east at latitudes far away from the Equator and towards the ESE at Equatorial latitudes.

Over the course of the next fortnight, Venus passes several degrees North of Sagittarius' famous asterism, the Teapot, which comprises eight stars of third-magnitude or brighter (although since the constellation is only now beginning to emerge into the dawn sky, they are not all visible at this time of the year). On January 9th Venus passes 7.2 North of the star Alnasl (Greek lower-case letter 'gamma' Sgr or Gamma Sagittarii, mag. +3.0), positioned at the front of the Archer's bow. Prior to IAU standardisation in 2016 it was variously known by the names Nash or Alnasr, among others. On January 11th the planet passes 2.1 South of the star Polis (Greek lower-case letter 'mu' Sgr or Mu Sagittarii, mag. +3.8v), positioned just to the North-west of the Teapot. It is an eclipsing binary star with a tiny brightness variation of 0.1 magnitudes.

On January 12th Venus passes 6.7 North of the star Kaus Media (Greek lower-case letter 'delta' Sgr or Delta Sagittarii, mag. +2.7), positioned at the centre of the Archer's bow. Before IAU standardisation it was also known by the names Kaus Meridionalis and Kaus Medius. On January 13th the planet passes 11.2 North of Sagittarius' brightest star Kaus Australis (Greek lower-case letter 'epsilon' Sgr or Epsilon Sagittarii, mag. +1.8). Given that it was designated the Greek letter epsilon, one might expect Kaus Australis to be the fifth-brightest star in the constellation. However, it is one of many examples in the night sky where the brightest star in the constellation was not assigned the correct letter - namely, alpha (Greek lower-case letter 'alpha').

Later on January 13th, the planet passes 2.2 North of the star Kaus Borealis (Greek lower-case letter 'lambda' Sgr or Lambda Sagittarii, mag. +2.8) which marks the top of the Teapot asterism (and the top of the Archer's bow). The name Kaus is Arabic for 'bow', its Northern and Southern sections (Borealis and Australis) being later Latin additions.

Venus crosses to the South of the ecliptic on January 16th. Observers at mid-Northern latitudes begin to have difficulty detecting the planet from around this time. From 50 North latitude, Venus is now rising in the South-east just 1 hour ahead of the Sun, barely reaching an altitude of 5 above the horizon before disappearing into the brightening twilight.

By the time the planet's solar elongation falls below 15 on January 24th, Venus is again rising in twilight across the inhabited world.

2 0 2 1  February

Venus enters Capricornus, the Sea Goat, on February 1st. Observers at Northern Tropical latitudes now see Venus rising just 40 minutes before sunrise, the planet appearing lower above the ESE horizon with each passing day.

On February 6th Venus passes 0.4 South of the planet Saturn (mag. +0.6), however the narrow solar elongation of 12 renders the ringed planet unobservable in the bright dawn twilight. Saturn's 2021 apparition will begin within the next couple of weeks.

On February 11th, at the closing stage of the apparition, Venus is involved in a planetary conjunction - the only one of the apparition which is observable. However, because of the narrow solar elongation it is a difficult one to observe and is visible only from Equatorial and Southerly latitudes. Venus passes 0.4 to the South of Jupiter which, like Saturn, is now emerging into the dawn sky at the very start of its 2021 apparition. For more details on this single conjunction, see the planetary conjunctions section below.

By mid-February Equatorial and Southern latitudes see Venus rising in the East some 50 minutes ahead of the Sun, the planet rapidly losing altitude above the horizon as its solar elongation falls below 10. On February 13th the planet passes 4.5 to the South of Mercury (mag. +2.8) as the latter planet moves retrograde through the Western section of Aquarius, the Water Bearer. Again, the narrow solar elongation renders Mercury unobservable; it will become visible in the dawn sky within the next few days, the first of the planet's six apparitions in 2021.

Venus ends the 2020-21 morning apparition shining at nearly the same apparent magnitude (-3.8) as when it had entered the morning sky in the previous June, the planet now showing a 98% illuminated disk measuring just 10" across. Venus becomes lost from view in the dawn twilight as it approaches the Capricornian boundary with Aquarius, which it enters on February 23rd.

2 0 2 1  March

On March 14th Venus passes only 24' (0.4) South of the planet Neptune (mag. +7.9) in an unobservable planetary conjunction positioned only 3.4 from the Sun. At this time the two planets are just 1.5 South of the Aquarian border with Pisces, the Fishes.

Venus enters Pisces on March 17th and reaches superior conjunction (passing behind the Sun as seen from the Earth) near the central Pisces-Cetus border on March 26th. At the moment of conjunction the planet is positioned 1.3 South of the Sun. Venus is now at a very distant 1.7312 AU (258.9 million kms or 160.9 million miles) from the Earth. Were it to be visible from the Earth at this point, Venus would have an apparent diameter of just 9".7 and would shine at magnitude -3.8.

Having passed from the morning to the evening sky, Venus remains out of view - lost in the solar glare - for over a month, as it makes its slow passage on the far side of its orbit from the Earth. The planet becomes visible once again from around early May 2021, when it is seen shortly after sunset from Equatorial latitudes as an 'Evening Star' in the Western sky, heralding a new evening apparition (2021-22) which lasts through to January 2022.

 [Terms in yellow italics are explained in greater detail in an associated article describing planetary movements in the night sky.]

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Venus Conjunctions with other Planets: Morning Apparition, 2020-21

Viewed from the orbiting Earth, whenever two planets appear to pass each other in the night sky (a line-of-sight effect) the event is known as a planetary conjunction or appulse. Not all planetary conjunctions will be visible from the Earth, however, because many of them take place too close to the Sun. Furthermore, not all of them will be seen from across the world; the observers' latitude will affect the altitude (angle above the horizon) at which the two planets are seen at the time of the event and the local season will affect the sky brightness at that particular time. A flat, unobstructed horizon will normally be required to observe most of them.

Planetary conjunctions are generally considered most noteworthy when they involve two bright planets, and none are more spectacular than those involving Venus. During the course of a typical Venusian apparition, Venus moves through eight or more zodiac constellations and in doing so it passes other planets in the sky - and in the case of Mercury, often on more than one occasion.

Because Venus never appears more than 47 from the Sun, it follows that any planetary conjunction involving Venus will also never occur above this angular distance, i.e. its solar elongation will always be less than 47. For an Earthbound observer, a superior planet (i.e. Mars and beyond) seen at such a small elongation poses something of a problem, since it will then be considerably more distant from the Earth - and therefore fainter - than when it is closest and brightest in the sky (namely, at opposition, when its elongation is 180 from the Sun). Jupiter is affected to a much lesser extent since it is always above magnitude -1.6 (brighter than Sirius, the brightest star in the sky).

A significant factor in determining whether a planetary conjunction is 'easy' or 'difficult' is the altitude that the fainter planet is positioned as it disappears from view in the dawn twilight. This in turn affects the duration for which the pair are visible before sunrise.

A Venusian apparition typically involves three or four observable planetary conjunctions, however the planet's 2020-21 morning apparition is unusual in that it only has one: on February 11th 2021, when Venus passes 0.4 to the South of Jupiter. The conjunction takes place very late in the apparition, when Venus is only days away from disappearing into the bright dawn twilight. Because of the narrow solar elongation of 11 the conjunction is only visible from Equatorial and Southerly latitudes, where the ecliptic (the apparent path of the Sun, Moon and planets) presents a steep angle to the horizon at dawn at this time of year. The conjunction occurs just as Jupiter (mag. -1.8) is emerging into the dawn sky at the start of its 2021 apparition. But even from optimal latitudes the conjunction is seen low above the ESE horizon and is difficult to view. As the fainter planet (Jupiter) disappears from view in the twilight, observers situated between latitudes 25 and 35 South see the two planets attain an altitude of only 6 above the horizon, while at the Equator and latitude 45 South the pair are less than 5 high. In practice, observers have less than 20 minutes in which to observe the conjunction. Also becoming visible some 6 to the ESE of the pair, having risen a little earlier, is the planet Saturn (mag. +0.6) which is now at the start of its own 2021 apparition.

The only planetary conjunction involving Venus which is observable during the 2020-21 morning apparition is summarised in the table below.

Table showing the observable Venus conjunctions with other planets during the morning apparition of 2020-21 (Copyright Martn J Powell, 2020)

Venus conjunctions with other planets during the 2020-21 morning apparition The column headed 'UT' is the Universal Time (equivalent to GMT) of the conjunction (in hrs : mins). The separation (column 'Sep') is the angular distance between the two planets, measured relative to Venus, i.e. on 2021 Feb 11 Jupiter is positioned 0.4 North of Venus at the time shown. The 'Fav. Hem' column shows the Hemisphere in which the conjunction is best observed (Northern, Southern and/or Equatorial). The 'Con' column shows the constellation in which the planets are positioned at the time of the conjunction.

Although any given conjunction takes place at a particular instant in time, it is worth pointing out that, because of the planets' relatively slow daily motions, such events are interesting to observe for several days both before and after the actual conjunction date.

There are in fact two methods of defining a planetary conjunction date: one is measured in Right Ascension (i.e. perpendicular to the celestial equator) and the other is measured along the ecliptic, which is inclined at 23 to the Earth's equatorial plane (this is due to the tilt of the Earth's axis in space). An animation showing how conjunction dates are determined by each method can be found on the Jupiter-Uranus 2010-11 triple conjunction page. Although conjunction dates measured along the ecliptic are technically more accurate (separations between planets can be significantly closer) the Right Ascension method is the more commonly used, and it is the one which is adopted here.

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Moon near Venus Dates, June 2020 to February 2021

The Moon is easy to find, and on one or two days in each month, it passes Venus in the sky. Use the following tables to see on which dates the Moon passes near the planet between June 2020 and February 2021:

Date Range

(World)

Conjunction (Geocentric)

Solar Elong.

Moon Phase

Date & Time

Sep. & Dir.

2020

Jun 18/19*

Jun 19, 08:53 UT

0.7 S

22W

Waning Crescent

throughout

Jul 16/17

Jul 17, 07:25 UT

3.1 S

42W

Aug 15/16

Aug 15, 12:59 UT

4.0 S

45W

Sep 13/14

Sep 14, 04:42 UT

4.5 S

43W

Oct 13/14

Oct 13, 23:55 UT

4.3 S

38W

Nov 12/13

Nov 12, 21:29 UT

3.0 S

31W

Dec 12/13

Dec 12, 20:39 UT

0.8 S

25W

2021

Jan 11/12

Jan 11, 20:09 UT

1.5 N

18W

Waning Crescent

throughout

Feb 10/11

Feb 10, 21h UT

2.5 N

11W

*  A lunar occultation takes place, visible in twilight from the Northern central Atlantic Ocean, NE Canada (New Brunswick, Nova Scotia, E Quebec, Newfoundland, SW Labrador) and NE USA (Maine). See The National Astronomical Observatory of Japan website for visibility track and timings.

 A lunar occultation takes place, visible in twilight from the NW Pacific Ocean, the NE tip of Russia (Kamchatka, E Chukotka), the Bering Sea and the NW tip of the USA (N Alaska). See the NAOJ website for visibility track and timings.

Moon near Venus dates for the morning apparition of 2020-21. The Date Range shows the range of dates worldwide (allowing for Time Zone differences across East and West hemispheres). Note that the dates, times and separations at conjunction (i.e. when the two bodies are at the same Right Ascension) are measured from the Earth's centre (geocentric) and not from the Earth's surface (times are Universal Time [UT], equivalent to GMT). The Sep. & Dir. column gives the angular distance (separation) and direction of the planet relative to the Moon, e.g. on August 15th 2020 at 12:59 UT, Venus is positioned 4.0 South of the Moon's centre.

 

A waning crescent Moon and Venus photographed on the morning of August 19th, 2017 (Photo: Copyright Martin J Powell, 2017)

The Waning Crescent Moon and Venus in the Eastern sky before dawn, photographed by the writer on August 19th 2017. Venus was positioned 2.9 North of the Moon, as seen from the South-western United Kingdom. Note the effect of earthshine on the unlit portion of the Moon, caused by the Earth's reflected light. A naked-eye effect called irradiation causes the brightly lit crescent to appear part of a larger disk than that of the unlit portion of the Moon.

Because Venus never appears more than 47 from the Sun, the Moon always shows a crescent phase whenever it passes the planet in the sky: a waxing crescent during evening apparitions and a waning crescent during morning apparitions.

The Moon moves relatively quickly against the background stars in an Eastward direction, at about its own angular width (0.5) each hour (about 12.2 per day). Because it is relatively close to the Earth, an effect called parallax causes it to appear in a slightly different position (against the background stars) when seen from any two locations on the globe at any given instant; the further apart the locations, the greater the Moon's apparent displacement against the background stars. Therefore, for any given date and time listed in the table, the Moon will appear closer to Venus when seen from some locations than others. For this reason, the dates shown in the table should be used only for general guidance.

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Naked-eye Venus: Apparitions, Conjunctions and Elongations, 2010-2020

The Naked-eye appearance of Venus

Naked Eye Planet Index

Planetary Movements through the Zodiac

Mercury

Venus 

Mars

Jupiter

Saturn

Uranus

Neptune

Pluto


Credits


Copyright  Martin J Powell  June 2020


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