The Venus Evening Apparition of 2011-2012

by Martin J. Powell

Following superior conjunction on August 16th 2011 (when it passed directly behind the Sun in the constellation of Leo) Venus' 2011-12 apparition as an 'Evening Star' began as the planet emerged in the dusk sky in late September 2011. The time of year at which the planet became visible depended upon the observer's latitude; Equatorial and Southern latitudes were first to see it, low down in the West shortly after sunset. The further North the observer was located, the later the planet emerged; hence high-Northern latitudes did not begin to see Venus until around late November 2011.

The planet was slow to emerge from the twilight glow, taking several weeks to gain a significant altitude (angle above the horizon) after sunset. At this early stage of the apparition, when seen through a telescope, the planet showed a broad gibbous phase, around 98% illuminated, shining at an apparent magnitude of -3.8 and measuring only around 10" across (i.e. 10 arcseconds, where 1" = 1/60th of an arcminute or 1/3600 of a degree). Its low altitude, great distance from the Earth and small apparent size made it a difficult object to observe telescopically, with no detail being visible in its clouds. The planet was positioned in central Virgo as the apparition began, moving South-eastwards along the ecliptic (the apparent path of the Sun, Moon and planets) at a steady rate of about 1°.2 per day.

On September 30th 2011, Venus passed 1°.3 South of Saturn, in an event known as a planetary conjunction. However, Saturn's 2010-11 apparition was now drawing to a close and at magnitude +0.9 it was barely bright enough to see, low down in the dusk twilight. From Southerly latitudes, Venus, at magnitude -3.8, was more easily discerned in the twilight.

From early to mid-October, observers in Northern Tropical latitudes began to detect the planet, low in the West after sunset. Having spent five weeks in Virgo, the Virgin, Venus entered Libra, the Balance (or Scales) on October 15th. Now at a more comfortable solar elongation of 18°, the planet passed 9' South (i.e. 9 arcminutes, where 1' = 1/60th of a degree) of the double star Zuben Elgenubi ( Lib or Alpha Librae, mag. +2.8) on October 21st. Around this time, mid-Northern latitudes began to detect the planet, low in the West-South-west after sunset.

From around October 22nd, Venus was joined from the West by Mercury, now emerging into the evening sky for an apparition which favoured Southern hemisphere observers. At this point in time, Mercury's apparent motion against the background stars was swifter than that of Venus, so that Mercury slowly closed in on Venus over the next couple of weeks. Venus entered the constellation of Scorpius, the Scorpion, on November 2nd, followed only hours later by Mercury on the same day. Five days later (on November 8th) Venus entered Ophiuchus, the Serpent Bearer, Mercury following it several hours later on November 9th. The two planets came closest together on November 9th, being 2° apart, although they did not actually reach conjunction (see below for details of other planetary conjunctions with Venus during the 2011-12 apparition).

Venus, Mercury and the orange-red star Antares ( Sco or Alpha Scorpii, mag. +1.0v) formed an interesting line-up 3°.9 in length on November 10th, Venus being the most Northerly of the three with Mercury at the centre. The line-up was only visible from latitudes South of about 30° South.

Mercury briefly exited Ophiuchus and re-entered Scorpius on November 12th, reaching its greatest elongation from the Sun on November 14th, when it was positioned 23° East of the Sun and shone at an apparent magnitude of -0.2. The planet spent just three days in Scorpius before returning to Ophiuchus on November 15th. Its apparent motion also began to slow, so that Venus began to pull away from Mercury towards the East. Mercury reached its Eastern stationary point on November 24th, at which point it was positioned 6°.7 to the West of Venus. Mercury's evening apparition ended only days later as it disappeared from view into the dusk twilight.

On November 23rd 2011, Venus entered Sagittarius, the Archer, the most Southerly constellation of the zodiac. Six days later (November 29th) the planet attained its most Southerly position in the zodiac for the 2011-12 apparition, with a declination of -24°.76 (i.e. 24°.76 South of the celestial equator). Venus then set at its most Southerly point along the local horizon, an effect which was more pronounced the further away from the Equator an observer was situated.  For example, at the Equator (latitude 0°) Venus set in the West-South-west at this time whilst at 55° North (where observers were only just beginning to see it) the planet set in the South-west, some 20° further South along the horizon.

From November 27th to December 9th 2011, Venus passed to the North of the asterism (star pattern) commonly known as The Teapot. Seen in a North-up orientation, the teapot appears 'tipped up', pouring its contents South-westwards into neighbouring Scorpius. The asterism extends from the star Al Nasl ( Sgr or Gamma Sagittarii, mag. +3.0) in the West to the star Tau Sagittarii ( Sgr, mag. +3.3) in the East. On December 1st Venus passed 42' (0°.7) North of Kaus Borealis ( Sgr or Lambda Sagittarii, mag. +2.8) at the top of the teapot and five days later (December 6th) the planet passed 1°.9 North of the constellation's second-brightest star Nunki ( Sgr or Alpha Sagittarii, mag. +2.0) in the handle of the teapot. Finally, on December 8th Venus passed 5°.6 North of the star Ascella ( Sgr or Zeta Sagittarii, mag. +2.6) at the base of the teapot's handle.

Around this time, observers at mid-Southern latitudes saw Venus attain its highest altitude in the sky after sunset for the 2011-12 apparition. At 45° South latitude in early December, Venus was around 15° high at 30 minutes after sunset, the planet itself setting over two hours after the Sun. At 35° South in mid-December, the planet attained 18° altitude at 30 minutes after sunset. The significance of the observer's latitude in observing planets at narrow solar elongations was well illustrated at this time; whilst mid-Southern hemisphere observers were enjoying their best views of Venus around mid-December, observers at 60° North latitude were only just catching their first glimpse of the planet after sunset (details of the planet's direction and altitude at 30 minutes after sunset for various latitudes are listed in the table below).

On December 20th 2011 Venus entered Capricornus, the Sea Goat, passing 6°.5 South of the constellation's second-brightest star Dabih ( Cap or Beta Capricorni, mag. +3.1) on December 22nd. The Northern hemisphere winter solstice now having passed, both Venus and the Sun began to ascend the ecliptic once more. With the declination of both celestial bodies moving Northwards and the solar elongation of Venus continuing to increase over the next few months, the setting positions of both Venus and the Sun moved further North along the local horizon with each passing week. Venus passed 1°.3 South of Theta Capricorni ( Cap, mag. +4.0) on December 31st and 27' (0°.45) South of Iota Capricorni ( Cap, mag. +4.2) on January 4th 2012. The Sea Goat's tail stars of Nashira ( Cap or Gamma Capricorni, mag. +3.7) and Deneb Algiedi ( Cap or Delta Capricorni, mag. +2.9) were passed to the North by Venus on January 7th and 9th, the separations being 52' (0°.86) and 57' (0°.95) respectively.

By late December 2011, Venus was setting in darkness from all but the Polar regions of the world. Shining brightly above the rooftops after dark during the festive season, the planet was easily associated with the 'Star of Bethlehem' in the Nativity story. This particular 'star', however, was seen in the West and not in the East.

With the arrival of 2012, Venus had brightened to -3.9 and its apparent size had reached 13". Telescopes showed a notably gibbous phase, about 80% illuminated. On January 11th 2012 Venus entered the constellation of Aquarius, the Water-Bearer. Soon afterwards the planet exited the Chart 1 coverage, after which it encountered the planet Neptune, which had entered the constellation in January 2011 and will remain there until 2022. On January 13th the Solar System's brightest and faintest naked-eye planets came to within 1°.1 of each other in the Earth's night sky, some 36° East of the Sun, Neptune being the more Northerly of the two. Since Neptune is always below naked-eye visibility, this planetary conjunction required optical aid. However, the sheer brilliance of Venus (at mag. -3.9) and the faintness of Neptune (mag. +7.9) made it an uncomfortable conjunction to view. Four hours after its conjunction with the distant planet, Venus passed 29' (about the apparent width of the Full Moon) to the North of the fourth-magnitude star Iota Aquarii ( Aqr).

As Venus re-joined the star chart coverage in Chart 2 (top of page), it was positioned in central Aquarius, some 4°.5 South of the star Ancha ( Aqr or Theta Aquarii, mag. +4.1) which it passed on January 15th 2012. Between January 16th and 19th the planet passed to the South of Aquarius' most recognisable feature: the asterism informally known as The Steering Wheel, which is centred on the star Zeta Aquarii ( Aqr, mag. +3.6) . On January 28th the planet passed just 2' (about eight apparent Venus-widths) to the South of the star Phi Aquarii ( Aqr, mag. +4.2), which marks the top of the amphora from which the Water-Bearer figure pours his water.

Around mid-January 2012, observers in Southern Tropical latitudes saw Venus reach its highest altitude after sunset. From latitude 25° South, the planet was positioned 21° above the Western horizon (at 30 minutes after sunset) and set two hours after the Sun.

Venus entered Pisces, the Fishes, on February 2nd, crossing the celestial equator (declination = 0°) in a Northward direction on February 9th. The following day (February 10th) the planet encountered Uranus, passing 21' (0°.35) to the North of the blue-green planet. The separation was easily contained within a low-power telescope eyepiece, however the conjunction had the same problem as that for Neptune only a month earlier: namely, the brilliance of Venus confounding the ease of viewing. In this case the problem was somewhat less since Venus shone at a magnitude of -4.0 whilst Uranus was a more comfortable +5.9.

On February 16th Venus crossed the ecliptic heading Northwards, then on February 19th it passed 2° South of the star Delta Piscium ( Psc, mag. +4.4). Four days later the planet passed 37' (0°.6) South of Epsilon Piscium ( Psc, mag. +4.2). Now approaching Pisces' Eastern border with Aries, the Ram, Venus passed 3°.3 North of the fancifully-named star Torcularis Septentrionalis ( Psc or Omicron Piscium, mag. +4.2) on March 4th. The planet entered Aries just 7 hours later.

Venus' passage through the small constellation of Aries was an eventful one, involving both a planetary conjunction and a maximum solar elongation. On March 6th 2012 Venus passed 7°.4 South of Aries' second-brightest star Sheratan ( Ari or Beta Arietis, mag. +2.6), then on March 9th it passed 8°.7 South of its brightest star Hamal ( Ari or Alpha Arietis, mag. +2.0).

On March 15th 2012, Venus passed the bright planet Jupiter in a spectacular planetary conjunction which was easily the best of Venus' 2011-12 apparition. The conjunction was well-placed for Northern hemisphere observers in particular. Jupiter, which had been dominating this region of the sky for several months, was now magnitude -1.9 (having faded somewhat since its opposition in the previous October) and was positioned 3°.3 to the South of Venus (which had now brightened to mag. -4.2). When assessed in terms of visual impact and ease of viewing, the March 2012 Venus-Jupiter conjunction was the best to take place between any of the planets until mid-2015.

Around mid- to late March, observers in Equatorial latitudes saw Venus attain its highest altitude above the local horizon for the 2011-12 apparition, the planet being some 31° high in the West-North-west at 30 minutes after sunset (the scenario is shown in the form of a horizon diagram below). At these latitudes, the planet now remained visible for almost three hours after sunset.

On March 25th 2012 Venus passed 1°.2 North of the star Botein ( Ari or Delta Arietis, mag. +4.3), the Easternmost star of the Ram figure. Venus reached its greatest elongation from the Sun for this apparition (46°.03 East) on March 27th 2012, when it was positioned about 2°.3 to the North-east of Botein. At this stage, telescopes showed Venus' disk half-illuminated (phase = 0.50 or 50%) with an apparent diameter of  23".5. Although the greatest elongation from the Sun occurred on March 27th, Venus was in fact positioned at precisely 46°.0 elongation for a ten-day period from March 22nd through to April 1st.

For a few days around greatest elongation, telescopic observers often look to find the precise moment when the terminator (the line seperating the light and dark sides of the planet) appears perfectly straight, essentially dividing Venus into two perfect halves. Solar System geometry suggests that this should occur on greatest elongation day, however it often does not and the precise reason for this is not fully understood. This anomaly is known as Schröter's Effect and it is well-known amongst telescopic observers of the planet.

For Northern hemisphere observers, the date of Venus' maximum solar elongation in 2012 was ideal, since it coincided with the period during which the planet attained its highest position above the local horizon after sunset. From late March into early April of 2012, for example, observers at latitude 30° North saw the planet attain a significant 38° above the local horizon at 30 minutes after sunset - the highest altitude attained from any latitude during the 2011-12 apparition. Higher latitudes did not fare much worse. Even from latitude 60° North, in late March 2012, the planet was placed 32° above the local horizon at 30 minutes after sunset. This ideal set of circumstances meant that Venus remained visible after sunset for between 3½ hours (at 30° North) and 5½ hours (at 60° North)!

For the naked-eye planet observer situated at mid- and high-Northern latitudes, Venus' 2011-12 apparition was the best evening apparition in the planet's apparition 'cycle' (there being five evening and five morning apparitions in each Venusian 8-year 'cycle'). For Equatorial and Southern hemisphere observers, it was the worst evening apparition in the 'cycle'. For telescopic observers of the planet, however, the relatively high placement of Venus in the sky after sunset is of little benefit. Because of the planet's glare when seen against a darkening sky, coupled with the Earth's troublesome atmospheric turbulence at low altitudes, most telescope users observe the planet in full daylight, when it is high above the horizon and more easily seen against a brighter sky. Of course, extreme caution must be taken when attempting to observe any of the planets in daylight and the Sun must be positioned at a safe angular distance from the planet and be fully shielded from view.

Venus entered Taurus, the Bull, on March 30th 2012, where it remained through to the end of the 2011-12 apparition. On April 3rd the planet passed South of the open star cluster known as the Pleiades (pronounced 'PLY-add-eez' or 'PLEE-add-eez'), designated Messier 45 (M45) by the French astronomer Charles Messier (1730-1817) who published his first catalogue of nebulous objects in 1774. Also known by the name The Seven Sisters, they are probably the best-known star cluster in the night sky. Under dark skies the seven brightest stars in the group can be seen with the naked-eye; they are Alcyone ( Tauri or Eta Tauri, mag. +2.9), Atlas (mag. +3.6), Electra (mag. +3.7), Merope (mag. +4.2), Taygete (mag. +4.3), Pleione (mag. +5.1v) and Celaeno (mag. +5.5). Venus took a little over a day to traverse the apparent width of the Pleiades, passing 35' (0°.6) South of Electra (the Westernmost naked-eye star of the group) on April 3rd and then 14' (0°.2) South of Atlas (the Easternmost naked-eye star of the group) on April 4th.

From April 12th to April 17th 2012 Venus passed to the North of the large V-shaped star cluster known as the Hyades. Although an obvious cluster to the naked eye, Charles Messier did not include it in his catalogue (he was looking for objects which could be confused with comets - and the Hyades certainly do not look like a comet!) The cluster comprises around 200 stars spread over an exceptionally large area of about 5° of the sky. Although it does not have a Messier number, the Hyades do have other catalogue references, namely Melotte 25, Collinder 50 and Caldwell 41 (the latter being the most recent, catalogued by the British astronomy-writer and TV presenter Sir Patrick Moore in 1995).

On April 12th, Venus passed 10°.1 North of the Hyades' Westernmost star Hyadum Primus ( Tauri, mag. +3.6) which is positioned at the vertex of the 'V'-shape. On April 17th the planet passed 10° North of Taurus' brightest star Aldebaran ( Tauri, mag. +0.9). Aldebaran is a red giant star which appears as the Easternmost star of the cluster but in fact, it is not a physical member of the Hyades group; its appearance in the cluster is purely a line-of-sight effect. The Hyades lie at a distance of about 150 light years from Earth (where 1 light year = 63,240 Astronomical Units), whereas Aldebaran is much closer, at 68 light years.

As Venus proceeded towards the North-eastern corner of Taurus, its apparent motion against the background stars was slowing. When it entered Taurus in late March 2012 its apparent motion was about 1° per day but by the close of April its apparent daily motion had slowed to 0°.5. The solar elongation was also narrowing, having reduced from 46° in late March to around 40° in late April. Since greatest elongation day Venus had been showing a crescent phase through telescopes, its apparent size slowly enlarging with each passing day.

The planet attained its greatest brilliancy for this apparition (mag. -4.4) on April 30th 2012. 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 2012 this took place when the planet was 27% illuminated (phase = 0.27), its angular diameter was 37".4 and its solar elongation was 39°.8. Thirty minutes after sunset, naked-eye observers in the Northern hemisphere now saw Venus in its true majestic brilliance against a dark sky, positioned some 30° high above the Western horizon. For much of the Southern hemisphere, Venus was brilliant and the sky was dark, but the planet was less than 20° above the horizon at 30 minutes after sunset.

On May 4th Venus attained its most Northerly declination for this apparition (+27°.82) which is the most Northerly declination attained by the planet during both 20th and 21st centuries! The planet was now 4°.7 North of the ecliptic (ecliptic latitude = +4°.7) and only 51' (0°.85) South of Taurus' boundary with Auriga, the Charioteer. Across the world, the planet now set at its most Northerly point along the local horizon.

Venus passed 48' (0°.8) South of the star Nath ( Tau or Beta Tauri, mag. +1.7) on May 7th. Nath (also spelled Alnath or El Nath) marks the tip of the Bull's Northern horn, but it is also shared by Auriga, the Charioteer, being its most Southerly star. The planet's apparent motion continued to slow until, on May 15th, its Eastward motion ceased when it reached its Eastern stationary point, 1°.8 to the South-east of Nath. Thereafter Venus moved retrograde (East to West) against the background stars, its declination (and ecliptic latitude) reducing as it accelerated towards the close of its 2011-12 apparition. The planet passed 2°.4 South of Nath on May 23rd, an event which was difficult to view from high-Southern latitudes because of Venus' low altitude after sunset.

From around mid-May 2012, steadily-held binoculars began to detect Venus as a tiny crescent soon after sunset as the planet languished low in the West-North-western sky. Telescopes showed a large, thin crescent at this point, nearly 50" in diameter, the image greatly disturbed by the Earth's turbulent atmosphere and split into the rainbow colours by an effect called dispersion (an example of how dispersion appears through a telescope can be seen here). Its solar elongation now having reduced below 30°, observers at mid-Southern latitudes began to have some difficulty viewing Venus as it sank into the bright dusk twilight.

As the Venusian crescent continued to enlarge it also becomes more slender, such that the dark (non-illuminated) side of the planet was well-displayed when seen from the Earth. With the aid of ultraviolet and infrared filters, telescopic observers now began their search for the mysterious and elusive Ashen Light, a faint glowing of the night side of Venus which until recently had no clear explanation. Given the extremely high temperatures which are known to exist beneath the Venusian clouds, the Ashen Light is today considered by many to be a visual indication of the planet's surface glowing red hot.

In late May, observers with exceptionally-good eyesight may have attempted to observe the crescent of Venus with the naked-eye. Whilst this may seem extraordinary, the planet's apparent size of around 58" brings it very close to the generally-accepted resolution of the human eye, i.e. 1 arcminute. Because the planet's solar elongation was then around 15° or less, glare was no longer a problem because the planet was then seen in bright twilight through to its setting, theoretically allowing the crescent to be discerned more easily.

By early June, Venus became lost from view from all locations as it sped towards inferior conjunction (passing between the Earth and the Sun) on June 6th 2012. Under normal circumstances this would mark the end of the planet's evening apparition, however in 2012 (as in 2004) the spectacle was not yet over; indeed, the highlight of the apparition was about to take place. For on June 5th-6th 2012, viewed from the Earth, Venus was seen as a tiny black dot moving across the Sun's disk in a very rare event called a transit of Venus; for more details, see the 'Transit of Venus 2012' page.

After Venus' solar transit, the planet was once again lost from view, having passed from the evening to the morning sky. The period of non-visibility was brief, however; from mid-June 2012, Venus was seen rising as a 'Morning Star' in the Eastern sky shortly before the Sun, heralding a new morning apparition (2012-13) which lasted through to February 2013.

 [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 in 2012

Only three planetary conjunctions with Venus were viewable during the 2011-12 apparition.

The Venus and Jupiter conjunction of March 15th 2012 was easily the best of the apparition, both planets being positioned high in the Western sky after sunset.

Venus and Saturn were technically in conjunction on September 30th, when they were about 12° East of the Sun. Whilst Venus was then an easy naked-eye object after sunset (shining at an apparent magnitude of -3.8), Saturn (at mag. +1.0) was much more distant and almost five magnitudes fainter than Venus so that it was near-impossible to detect in the bright evening twilight glow. Owing to the difficulty in viewing it, this conjunction is not included in the table below.

Uranus and Neptune are rather more tricky objects to observe whenever they are involved in conjunctions with Venus, because Uranus is only just visible to the naked eye and Neptune never reaches naked-eye visibility. Twilight quickly renders these two planets invisible (even through binoculars), so conjunctions taking place less than about 20° from the Sun will be difficult or impossible to see. Even when the elongation is favourable, a further problem beckons in that the glare caused by Venus' brilliance makes it difficult to see the much fainter planet beside it. In such instances (e.g. for the Venus-Uranus conjunction of February 10th 2012) binocular observers may find it easier to position Venus just outside the binocular field of view so that the eye can more comfortably view the distant gas giant.

There were no visible conjunctions between Venus and Mercury during the 2011-12 apparition, however there was an interesting 'near miss' on 9th November 2011, when the two planets were some 22° East of the Sun on the Scorpius/Ophiuchus border. On this day, Mercury approached Venus to within just 0°.2 of celestial longitude and 2° in celestial latitude but they did not conjunct. In fact, the planets appeared to move almost parallel to each other for several days from around 7th to 11th November before drifting apart when Mercury's apparent motion slowed before reaching its Eastern stationary point. Since no conjunction occurred during this period, this event is excluded from the table below.

The three planetary conjunctions with Venus which were viewable during the 2011-12 apparition are listed in the table below.

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 23½° 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, September 2011 to May 2012

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 passed near the planet between September 2011 and May 2012:

The Moon moves relatively quickly against the background stars in an Eastward direction, at about its own angular width (0º.5) each hour (about 12º.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 have appeared 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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Direction, Altitude & Visibility Duration of Venus after Sunset, September 2011 to May 2012

The following tables give the direction and altitude (angle above the horizon) of Venus at 30 minutes after sunset, together with the visibility duration of the planet after sunset, for the 2011-12 evening apparition. An explanation of abbreviations in the tables is given in the box below. For the sake of convenience, the table is split into Northern and Southern hemisphere latitudes (the Equator is included in both tables to allow interpolation of the data for observers situated at Equatorial latitudes). The tables should prove sufficient to locate the planet in twilight, allowing telescope users to view the planet in comfort (because of Venus' brilliance, glare becomes a problem when the planet is seen through the eyepiece against a dark sky). Direction and Altitude diagrams are also provided below for intermediate latitudes of 55° North, 35° North, 30° South and the Equator.

The tables allow one to find the highest altitude in the sky which Venus attained for any given latitude during the 2011-12 evening apparition, and in which direction it was seen. For example, observers situated at latitude 40° North (a mid-Northern latitude) found the planet highest in the sky (at 30 minutes after sunset) in late March 2012, when it was seen at an altitude of 37° towards the West. The duration column shows that the planet was then above the horizon for about 4 hours after sunset.

Northern Hemisphere Latitudes

Southern Hemisphere Latitudes

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Direction & Altitude Diagrams (Horizon Diagrams) for the 2011-12 Evening Apparition

The following diagrams show an observer's Western horizon (from due South to due North) for latitudes of 55° North (a high-Northern latitude), 35° North (mid-Northern), the Equator and 30° South (mid-Southern). The path of Venus is plotted in the sky at 30 minutes after local sunset throughout the 2011-12 evening apparition with the planet's direction and altitude marked along the horizontal and vertical axes, respectively. Essentially, these diagrams show the same information as in the above look-up tables, but in an illustrative format, for the Equator and three intermediate latitudes.

For higher accuracy, the azimuth (the bearing measured clockwise from True North) is also shown along the direction axis. For each of the latitudes shown, the direction and altitude of Venus after sunset can be estimated for any part of the 2011-12 evening apparition by positioning your pointing device over each image, when an overlay grid will appear, marked at 10° intervals; the values can then be read off accordingly.

Although the dates indicated in the above diagrams refer specifically to the period 2011-12, Venus has an 8-year cycle of apparitions such that its position in the evening sky in 2011-12 will repeat very closely in the evening sky of 2019-20. The writer refers to this particular evening apparition as Apparition C1; for more details, see the accompanying article describing The Venus 8-year Cycle.

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Naked-eye Venus: Apparitions, Conjunctions and Elongations

Credits

• The star chart was created using by the commercial software MegaStar (by Willmann-Bell, Inc). Star colours were based on those shown in "Patrick Moore's Colour Star Atlas" (Mitchell Beazley Publishers Ltd., London, 1973).
• The dates of the planet's constellation boundary crossings were determined from the commercial software RedShift 5 by Maris Technologies Ltd and the daily rates of angular motion were derived from a BASIC computer program ('PLANLONG.BAS') written by the writer.
• The date of the most Northerly declination of Venus across two centuries (May 4th 2012) was obtained from the website 'The Sky and Its Phenomena' by Pierpaolo Ricci.
• The directions, altitudes and visibility durations of Venus were derived from RedShift 5.
• The times and separations of the lunar conjunctions with Venus (Moon near Venus dates) and the lunar phases were obtained from RedShift 5 using the 'Conjunctions' option of the 'Sky Diary'.

• The zodiac signs are courtesy of the free graphics site .

Copyright  Martin J Powell  October 2011