Jupiter during its 2017-2018 apparition

During its 2018-2019 apparition, Jupiter appears among the southern stars of Ophiuchus, the Snake Handler.  Just one apparition before its Great Conjunction with Saturn, Jupiter has two conjunctions with Venus.  Jupiter moves through southern Ophiuchus in front of dimmer stars  Its passage is worth noting in a dark sky or with binoculars.

The positions of Jupiter, sun and Earth at Jupiter’s conjunction on November 26, 2018.

Jupiter passes behind the sun early in the morning on November 26, 2018.  At this solar conjunction, Jupiter is not visible as it is hiding in the sun’s glare.   The chart above shows the position of Jupiter, sun and Earth at Jupiter’s conjunction.  From Earth, Jupiter is “behind” the sun.

Jupiter appears in front of the stars of Ophiuchus, the Snake Handler, during its 2018-2019 appearance.
(Artwork from Starry Night Pro)

The chart above shows the position of Jupiter in June 2019 compared to the background stars.  The sun, moon, and planets appear to move in front of a seemingly fixed background of stars we call the constellations.  They make familiar patterns.  The 88 constellations are also made of bright and dim stars outside those figures.  Constellation boundaries are irregularly-shaped patches of sky resembling a jumbled quilt or counties in a state.

To some, Ophiuchus is the “newly discovered 13th sign of the zodiac.”  This announcement is made every few years, but the constellation has existed since constellations were invented to track the skies of our ancestors.  There’s nothing new here.  The sun appears to move in front of Ophiuchus from about November 30 through December 17, 17 days compared to the 6 days it’s in front of the stars of Scorpius.  For most of its appearance during the next year, Jupiter shines from in front of stars of Ophiuchus’ feet.

This chart shows the relative motion of Jupiter compared to the background stars of Ophiuchus (Oph)
from December 24, 2018 through November 24, 2019.  Jupiter has two conjunctions with Venus
during this apparition. Greek letters are used to name the dimmer stars in the sky.

The planets appear to move eastward as they revolve around the sun.  They rise in the east and set in west each day as our planet rotates.  Jupiter moves slowly eastward compared to the distant stars, taking nearly 12 years to through all the constellations.  As our planet, moving 12 times faster, catches Jupiter nearly every year, Jupiter seems to stop moving eastward (April 10, 2019) and seems to move backwards or retrograde.  This is an optical illusion.  As it retrogrades, our planet passes between Jupiter and the sun (opposition, June 10, 2019).  After we pass by, Jupiter seems to stop retrograding (August 11, 2019) and appears to resume its forward or direct motion.  The illusion of the retrograde motion was one of the early challenges to explain.  If the earth were stationary, then must be a series of hoops that carried the planets.  The secondary hoops moved backwards at regular intervals, depending on the planet.  When it was clearly demonstrated that the earth moves (not an easy feat that was only demonstrated after the development of larger telescopes). the retrograde pattern was easily explained by a faster moving inner planet moving past a slower moving outer planet.

This chart shows the rising time of Jupiter and other bright celestial objects from Jupiter’s conjunction
until it rises 5 hours before sunrise.  Conjunctions with Mercury, Antares, and Venus are shown with
boxes.  The rising of the moon is shown with circles.  When the lines of two objects cross, they rise at the
same time.  Conjunctions can occur a few days before or after the intersection of the lines.  Chart
made from data by the U.S. Naval Observatory for Chicago, Illinois.

Slowly after conjunction, the planet begins to climb into the morning southeastern sky.  By December 3, it rises about 30 minutes before sunrise. Locate it in bright twilight with a binocular.  Watch it appear higher in the sky each morning at the same time.  Ten days later it rises about an hour before sunrise.  Thirty minutes before sunrise, it is only 5° up in the east-southeastern sky,  Near the middle of December, Jupiter rises at Nautical Twilight, about 65 minutes before sunrise.  At this time, the horizon is barely distinguishable.  Historically, this was important for sailors to be able to make celestial measurements for navigation that references the natural horizon with at sea.

Jupiter, Mercury, and Antares

As Jupiter emerges into the morning sky from its solar conjunction, it is grouped with Mercury and Antares.  Mercury passes Jupiter on December 21.  Brilliant Venus is far to the upper right of the grouping; it closes the gap early during Jupiter’s apparition.  Here are the details of the grouping.

This chart shows a time-lapse of 5 mornings, 45 minutes before sunrise, during late December.  Look
into the southeastern sky.  A binocular helps locate the dimmer stars.

• December 19: Jupiter is 0.8° to upper right of Omega Ophiuchi (ω Oph) and 5.3° to the upper left of Antares, although the star is only 3° in altitude. Use a binocular to find it.  Bright Mercury is 2.5° to the upper right of Jupiter and 1° to the upper right of Psi Ophiuchi (ψ Oph).
• December 20: At 45 minutes before sunrise, Jupiter is nearly 7° up in the southeast. The planet is 5.2° to the upper left of Antares.  Mercury is 1.6° to Jupiter’s upper right.

• December 21: Jupiter and Mercury are 0.9° apart this morning. Jupiter is 0.6° to the upper left of Omega Ophiuchi. Mercury, Jupiter, and Antares are nearly in a line spanning 6.1°. Today marks two years until the Great Conjunction of Jupiter and Saturn, when they appear 0.1° apart!
• December 22: At 45 minutes before sunrise, Mercury is 1.2° to the left of Jupiter. Jupiter is 25.2° to the lower left of brilliant Venus this morning.  Watch Venus close the gap during the next month

.

• December 23: Jupiter rises over 100 minutes before sunrise, at the beginning of twilight.  This morning, Jupiter passes 5.2° above Antares.  The Giant Planet appears 0.2° to the upper left of Omega Ophiuchi. Use a binocular or a small aperture telescope to resolve the pair.  The Jupiter-Mercury gap has grown to 2°.  Mercury is to the lower left of Jupiter.

By year’s end Jupiter rises over 2 hours before sunrise.  It is well off the southeastern horizon as twilight progresses.

Venus-Jupiter Conjunction

Early in the new year, Jupiter rises into the sky before twilight begins. Brilliant Venus and Jupiter approach a morning conjunction.  Venus rapidly moves eastward among the stars, about a degree a day compared to Jupiter.  They are heading for a widely-spaced conjunction on January 22. Watch the Venus-Jupiter gap close:  January 5, 15°; January 11, 10.1°; January 17, 5.1°.

• January 1, 2019: At the beginning of the new year, look for a wide grouping of the crescent moon, two planets, and a bright star. At 45 minutes before sunrise, the waning crescent moon is 29° up in the south-southeast, slightly below a virtual line that connects Zubenelgenubi (α Lib) and Zubeneschamali (β Lib).  Venus is 4.7° to the lower left of the moon.  Jupiter, 11° up in the southeast, is 18° to the lower left of Venus.  Antares is 5.5° to the lower right of Jupiter.

• January 22: At mid-twilight, 40 minutes before sunrise, the Venus-Jupiter pair appears 22° up in the southeast. Venus is 2.4° to the upper left of Jupiter in this widely-space conjunction. Watch Venus move away from Jupiter on the mornings that follow.

By the end of January, the Venus-Jupiter gap is nearly 8° .  Jupiter rises nearly 3 hours, 30 minutes before the sun.  At an hour before sunrise, Jupiter is 19°  up in the southeast.

Jupiter at Morning Quadrature

The positions of Jupiter, sun and Earth when Jupiter is 90° from the sun on March 13, 2019.

During March, Jupiter continues to rise earlier.  On March 1, it rises just after 2 a.m. local time.  On March 13, Jupiter around 2:30 a.m. CDT.   This morning it is 90° west of the sun.  As twilight begins, this Giant Planet is 25°  up in the south.  The planet continues to rise earlier and appear farther west during morning twilight.

On April 10 Jupiter begins to retrograde.  It is 15° to the upper left of Antares.  During the next six weeks, with a binocular, watch Jupiter move through the dim star field of southern Ophiuchus.  By April 19, the planet is rising before midnight, continuing to rise earlier each evening.  The time of its rising is very noticeable each week.  Our planet is catching Jupiter.

Jupiter at Opposition

The positions of the sun, Earth and Jupiter when Jupiter is at opposition, June 10, 2018.

On June 10, Earth passes between Jupiter and the sun.  Jupiter is nearly 400 million miles away. The sun and Jupiter are in opposite directions in the sky.  When the sun sets, Jupiter rises in the southeast.  It is south around midnight, setting in the southwest at sunrise.  After opposition, Jupiter rises in the sky before sunset.  By month’s end, Jupiter is well above the southeastern horizon as the sky darkens after sunset.

Jupiter continues to retrograde, reaching the farthest western point on August 11, 2019.

This chart shows the setting time of Jupiter and other bright celestial objects beginning with Jupiter setting 5 hours after sunset until its conjunction.  A conjunction occurs with Venus on November 24.
The setting moon is shown with circles.  When the lines of two objects cross, they set at the
same time.  Conjunctions can occur a few days before or after the intersection of the lines.  Chart
made from data by the U.S. Naval Observatory for Chicago, Illinois.

Jupiter appears on the setting chart in mid-August, when it sets 5 hours after sunset.  Notice how the Jupiter setting curve angles away from the Antares setting line and toward the Saturn setting line.  Jupiter’s setting curve intersects with Venus, indicating a conjunction (November 24).

Jupiter at Evening Quadrature

The positions of the sun, Earth, and Jupiter when Jupiter is 90° east of the sun, September 8, 2019.

Jupiter continues to appear higher in the sky each night as Earth pulls away.  On September 8, Jupiter is 90° from the sun in the evening sky,  Jupiter is in the south at sunset, setting at nearly 11:30 p.m. CDT.

From this point, Jupiter appears closer to the southwestern horizon at sunset.

A Second Venus-Jupiter Conjunction

During Venus’ evening apparition late in 2019, Venus passes Jupiter again.  Not a close (epoch) conjunction, but the planets are closer than January’s meeting.  The pair appears 1.4°  apart.  Start watching the Venus-Jupiter gap early in the month.  Here are the separations:

Nov 4:     20°
Nov 9:     15°
Nov 14:   10°
Nov 19:     5°
Nov 22:     2°

After the conjunction, the gap:

Nov 25:     2°
Nov 27:     7°

Toward Conjunction

On the evening of the conjunction with Venus, Jupiter sets as twilight ends, so begins its slow slide back into bright sunlight toward its solar conjunction.  As the Venus gaps grows, Jupiter sets at Nautical Twilight, (66 minutes after sunset) on December 6.  It sets at Civil Twilight (30 minutes after sunset) on December 17.  Civil Twilight is about the time that street lights turn on.

The positions of the sun, Earth, and Jupiter when Jupiter returns to its solar conjunction, December 27, 2019.

Jupiter’s appearance ends with its solar conjunction on December 29, 2019.  It then begins another appearance in the morning sky in 2020, the year of the Great Conjunction with Saturn when Jupiter passes very close to Saturn!

Jupiter and the Moon

Dates when Jupiter and the moon appear together

Before Opposition.

January 3:  3.5°
January 30/31:  6.2°/5.7°
February 27: 2°
March 27: 4.3°
April 23: 1°
May 20:  4.7°

After Opposition

June 16: 4.7°
July 13: 7.8°
August 9: 2.2°
September 5: 4°
October 3: 1.8°
October 31: 4.5°
November 28: 5.8°

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