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An Epoch Venus-Jupiter Conjunction: June 30, 2015


A recent Venus-Jupiter Conjunction

Venus passes close to Jupiter in the western evening sky during late June and early July in a dazzling celestial display. The image above shows the planets in 2012 when they passed within about 3 degrees of each other.  During the 2015 conjunction, the planets appear 9 times closer.  This article outlines the circumstances of conjunctions between Venus and Jupiter, the events of this conjunction, and concludes with a list of future Venus-Jupiter conjunctions.

See this article for more as Venus as an Evening Star.

Conjunctions of the bright planets occur when they appear to move past each other in the sky.  Sometimes they seem to nearly meet, although they are millions of miles apart.  A Venus-Jupiter conjunction occurs between 34 days and 449 days, depending on the relative positions of the three planets (including Earth).  Venus revolves around the sun once in about 225 days.  Because our planet is moving, Venus catches up to and passes by Earth every 584 days.  Jupiter is a slower moving participant in this celestial waltz as it revolves around the sun once in nearly 12 years.

Venus-Jupiter conjunctions occur somewhat frequently; the close ones of are great visual interest, because to the unaided eye, the planets appear to merge together.  While not a “once-in-a-lifetime”event, these close conjunctions are infrequent enough to attract the attention of even the casual sky watchers.  Robert C. Victor, former staff astronomer at Abrams Planetarium, calls these close conjunctions “epoch conjunctions.”

Venus is always visible near the sun as it is closer to the sun than Earth.  From our planet it never appears more than about 45 degrees from the sun.  When it is east of the sun, it appears in the western sky just after sunset.  When it is west of the sun, it appears in the eastern sky, just before sunrise.

Jupiter’s movement in the sky largely follows the earth’s revolution around the sun and mostly reflects the annual westward advancement of the starry background.  Jupiter first makes a morning appearance in the eastern sky, just past conjunction when Jupiter is on the far side of its orbit behind the sun.  Each week it appears higher in the sky and farther west at the same time each morning.  Several months later, it appears in the western sky just before sunrise from this slow westward celestial migration.  At this time it is at opposition with Earth between the sun and Jupiter; they are on opposite sides of our sky.  At this time, Jupiter rises a sunset, appears in the south at midnight and sets at sunrise — appearing in between at other times during the night.  Jupiter continues to rise earlier each week, eventually appearing in the south at sunset.  As Jupiter heads for conjunction (behind the sun) it appears in the western sky at sunset, eventually setting with the sun.  This entire cycle takes 399 days.

Because Venus’ orbit is inside Earth’s orbit, Venus never appears more than 45 degrees from the sun, the Venus-Jupiter conjunction appears within region of the sky when Jupiter is near conjunction.  Additionally, if the Venus-Jupiter conjunction occurs too close to the sun, the planets are hidden in the sun’s brilliant glare.  In recent times, 75% of the conjunctions occur when Venus and Jupiter are very close to the sun.

In sky watching we describe the separation of objects by an angle.  The angular size of the moon in the sky to our eye is about one-half degree (as measured on a protractor).  An angle can be further divided into 60 equal units, called minutes (60 minutes (‘) equals 1 degree; 30’ = one-half degree).

During the June 2015 conjunction, Venus is catching up to move between the earth and sun (Inferior conjunction).  Jupiter is nearing conjunction which is caused more by the earth’s revolution than Jupiter’s orbital movement.  The two planets are over 600 million miles apart, although they appear about 21′ (21 minutes= 0.3 degrees, less than a full moon diameter) apart.

The Epoch Conjunction

Week of June 1

Look west at 9:30 p.m., (the time for all the diagrams in this article), Venus dominates the western sky with its brilliance, 8 times brighter than Jupiter.  The Giant Planet is 20 degrees to the upper left Venus.  During the next week, the pair closes at about 30′ each day.  Venus is 5 degrees to the lower left of Pollux. (Click on the images in this sequence to see them larger.)

Meanwhile, Saturn is visible in the southeast near the moon on June 1.  Saturn and the star Antares are 11 degrees apart.

Week of June 8

Venus moves closer to our planet and continues to brighten, and Jupiter fades slightly as it is farther away each evening, Venus now outshines Jupiter nearly 9.5 times.  On Monday the planets are 14 degrees apart and continue to close about slightly more than 30′ each day.  Venus is 11 degrees to the upper left of Pollux.

Week of June 15

The planets are now 9 degrees apart and Venus is 10 times brighter than Jupiter.

 June 19 — The crescent moon joins the planetary pair (6.5 degrees apart).  It is 7 degrees below Venus.  June 20 — The moon is 5.5 degrees to the lower left of Jupiter; the planets are 6 degrees apart. Venus is 10.5 times brighter than Jupiter.

Week of June 22

June 22 — The planets are 4.5 degrees apart and Venus is nearly 11 times brighter than Jupiter.  June 21 –By week’s end, the planets are 1 degree (2 full moon diameters) apart.  The two brightest starlike objects in the night sky are near each other — but the spectacle is just beginning.

Week of June 29

On June 29, the planets are 41′ apart and Venus is nearly 11.5 times brighter than Jupiter.  They are one day from their closest visual approach.

 June 30 — The two planets seem to merge as they are 21′ apart!  Conjunction night!  Through a telescope at about 100 x, both planets are visible.  Venus has a distinct crescent shape.  Jupiter’s four largest and brightest moons are easy to see along with some detail in the planet’s cloud patterns.
 July 1 — The planets are 34′ apart and Venus is 11.5 times brighter than Jupiter.  July 2 — The separation grows to 1 degree with Venus 11.7 times brighter than Jupiter.

July 2015

On July 9, Venus reaches its greatest brilliancy as it continues to approach our planet and inferior conjunction.

 July 8 — The planets are 3 degrees apart with Venus over 12 times brighter than Jupiter.  The planets are distinctly lower in the sky.  July 15 — The planets are 5 degrees apart and lower yet in the sky.  Jupiter is heading toward conjunction and Venus to inferior conjunction.

Both planets continue to get lower in the western sky throughout the month of July.  By month’s end they set during evening twilight.  Venus passes between the earth and sun (inferior conjunction) on August 15.  Jupiter passes behind the sun (conjunction) on August 26.  Both move into the morning sky for a widely spaced conjunction (67′) on October 25.

The table below shows the next 8 close Venus-Jupiter conjunctions.  The November 2017 conjunction and the February 2025 event rival this conjunction in separation. The August 2016 conjunction is very close, yet the pair sets less than an hour after sunset.  Following the conjunctions mentioned on this list, a close conjunction (28′) occurs on August 23, 2038 followed by a closer conjunction occurs on November 2, 2039 (13′).  Other more widely spaced Venus-Jupiter conjunctions (30′ to 2 degrees) occur in the interim.

Conjunction Dates Separation Location Visibility
June 30, 2015 20’ Evening (west) Easy to see in western, visible in dark sky.  This conjunction is closest, visible conjunction for several years.
October 25, 2015 1 degree, 7 minutes Morning (east) Easy to see in eastern sky.  Planets high in eastern sky.  The planets are slightly over 2 full moon diameters apart.
August 27, 2016 7′ Evening(west) The planetary pair sets about 65 minutes after the sun.  Visible low in western sky during twilight.
November 13, 2017 20’ Morning(east) During this conjunction the planets rise in the east-southeast about 75 minutes  before sunrise.  In separation, it rivals the June 2015 conjunction, but it appears low in the sky.
November 24, 2019 1 degree, 28 minutes Evening(west) The planets in this widely spaced conjunction are nearly 3 full moon diameters apart.  They are visible low in the southwestern sky during twilight and early evening, setting about 1 hour, 35 minutes after sunset.
January 22, 2019 2 degrees, 24 minutes Morning (east) The planets in this widely spaced conjunction are far apart visually, but easily seen as they rise about 3 hours before sunrise and appear in low in the southeastern sky as morning twilight begins.
February 11, 2021 26’ Morning This pairing is very difficult to see in the eastern sky as the planets rise in bright twilight just 25 minutes before sunrise.
April 30, 2022 29’ Morning The planets rise in the eastern sky about 90 minutes before sunrise.  In separation, this rivals the June 2015 conjunction, although it is lower in the sky.
March 1, 2023 32’ Evening This conjunction rivals the June 2015 pairing, with the planets high in the west after sunset, setting 2 hours, 30 minutes after the sun.
May 23, 2024 15’ Morning This pairing is impossible for casual observers  to see as it occurs when the planets are nearly behind the sun hidden in the solar glare.

2021, October 29 – November 1, Lion Moon

October 29 – November 1, 2021:  The crescent moon moves in front of the stars of Leo in the eastern sky before sunrise.  Watch the moon appear lower and the phase shrink (wane) each morning. Also note that there is no Full moon on Halloween this year!

2021, October 25:  Caught Between the Horns

October 25, 2021: This morning the bright gibbous moon seems to be caught between the horns of Taurus.  Mercury is making its best morning appearance.  The planet pack – Venus, Jupiter, and Saturn are in the evening sky.

2021, October 24: Saturn Inches Toward Jupiter

October 24, 2021:  Saturn is at its closest to Jupiter as the Jovian Giant picks up eastward speed.  The morning moon and Mercury are visible before sunrise.  Brilliant Evening Star Venus, Saturn, and Jupiter are in the sky after sunset.

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