2017-2018: Jupiter’s Year in the Claws of the Scorpion, A Triple Conjunction

Figure 1:  Jupiter appeared in the morning sky in the fall of 2016.

Introduction

(There are many details in this article about Jupiter’s 2017-2018 appearance.  Bookmark it to return in the future.)

Jupiter last appeared in the morning sky in the fall of 2016 (Figure 1).  It appeared in front of the stars of Virgo, with a triple conjunction of Spica.

Jupiter begins a 397-day appearance on October 26, 2017, at its solar conjunction.  During this appearance it has a triple conjunction with the star Zubenelgenubi, the brightest star in Libra, conjunctions with Mars and Venus, and another close approach of Venus in 2018.

While the stars of Libra are not among the brightest stellar gems, the two brightest can be found from most street-lit areas.

Zubenelgenubi (“The Southern Claw”) and Zubeneschamali (“The Northern Claw”) may have been part of Scorpius.  Today some charts show the scorpion holding the scales in its claws.

In their book “Short Guide to Modern Star Names and Their Derivatives,” Paul Kunitzch and Tim Smart state, “The stars of Libra were interpreted by the Babylonians as ‘the Claws of the Scorpion’, and alternately (perhaps at a more recent stage) they were made an independent constellation,’the Balance'” (p. 43).

Zubenelgenubi and Zubeneschamali lie nearly midway between Spica and Antares.  Jupiter had a triple conjunction with Spica during its last apparition.  Spica is distinctly blue and Antares is reddish.  Spica lies near the ecliptic with the planets and moon passing it frequently.  Antares is about 5 degrees south of the ecliptic.  Planets can pass a few degrees away from it and the moon can pass relatively close.

Jupiter generally moves with the westward movement of the stars.  After its solar conjunction, it appears in the eastern sky morning sky.  Each week it appears noticeably higher in the east; this is from the earth’s revolution around the sun.  Each morning it appears higher in the sky as Earth rotates.  A few months after its first appearance, it appears south near sunrise.  Then it appears farther west near the horizon at sunset.  It then rises the east at sunset.  Again it appears higher and more westward each week from Earth’ revolution.  Late in its appearance Jupiter starts the evening in the west and as the weeks pass it disappears into the sun’s brilliant glare, completing its apparition.

In addition to its annual westward march, it moves it against the background stars.  Generally, the planets appear to move eastward against the starry background.  On occasions they seem to stop and backup, at a later date to resume their eastward planetary movement again.

A Triple Conjunction

A triple conjunction occurs when a planet appears to pass a star or another planet three times during a single appearance.  There are multiple definitions of a conjunction:  The simplest is the closest separation between a planet and another celestial object.  Two others are based on coordinate systems:  the solar system plane (ecliptic) and the plane of the earth’s equator (equatorial).  Coordinate systems have specific names for longitude and latitude.  In these systems conjunctions occur when the star’s longitude is the same the planet’s changing longitude as it revolves around the sun.  One could say that an airplane flying across the country is in conjunction with a city when its longitude matches the city’s longitude.  For our purposes a star’s celestial coordinates are constant while the planet’s coordinates change as it revolves around the sun.

Figure 2:  The celestial equator and the ecliptic.

Since the ecliptic is angled with the celestial equator by 23.5 degrees, a planet’s ecliptic longitude and equatorial longitude are not the same.  For this article, the triple conjunction occurs in the ecliptic coordinate system.  The charts in this article showing Jupiter’s long-term apparent motion are graphed with coordinates based on the ecliptic (Figure 2).

Jupiter begins its morning appearance on October 26, 2017 when the planet is  behind the sun in solar conjunction.

Jupiter completes one solar orbit about every 11 earth years.  Because Jupiter slowly lumbers through its orbital path, it does not travel far among the stars during the earth’s annual path around the sun.

Figure 3:  Jupiter’s solar conjunction, October 26, 2017.  The sun’s
bright glare blocks us from viewing Jupiter as the planet is
in the sky during daylight hours.

Notice that time is displayed on the chart (Figure 3).  Noon is defined as the line extending from Earth to the sun and beyond.  Any celestial object near that line appears in the sky with the sun and in the south when the sun is south (noon).  Midnight is the opposite direction.  Any star or planet appearing near the midnight line is in the sky nearly all night long, appearing in the south around midnight. (Clearly, by definition, the sun cannot appear in the sky at midnight.)  Mercury and Venus, being inside our planet’s orbit are frequently near the noon line or with 47 degrees of it.  They appear in either the eastern morning sky or western evening sky.  The outer planets can appear anytime in the sky and they are not restricted by lying inside our planet’s orbit.

Jupiter in the Morning Sky

 

Figure 4:  Jupiter rising in the eastern sky compared to sunrise.  The Giant Planet has conjunctions with Venus and Mars.

Jupiter then begins its appearance in the morning sky, initially rising during twilight.  By early November, it rises about an hour before sunrise.  The chart above shows the rising times of Jupiter, the star Spica, Venus, Mercury, and the moon (circles) compared to sunrise (Figure 4). (As the moon heads towards its new phase, it rises later –closer to sunrise — each morning.) The astronomical twilight line represents the time when the sky is as dark as it every gets naturally.  As the sky brightens, the ground can be discerned from the sky:  Nautical twilight.  So named because at sea the horizon clearly separates the water from the sky.  At Civil Twilight, the sky is bright, most details of terrestrial features can be identified.  Street lights normally turn off during the time between Civil Twilight and sunrise (or turn on during evening Civil Twilight).

Jupiter rises earlier each day, appearing higher in the eastern sky as sunrise approaches.  On November 13, Venus and Jupiter meet for an Epoch Conjunction.

Figure 5:  An Epoch Venus-Jupiter Conjunction

On this morning, brilliant Venus and bright Jupiter shine from low in the east-southeastern sky (Figure 5).  The pair is only about 5 degrees above the horizon. Venus is twice as bright as Jupiter.  On the morning before the conjunction, November 12, Venus is slightly less than one degree above Jupiter.   Spica is nearly 13 degrees to the upper right of  Venus; Mars is 23 degrees; and the moon is 55 degrees above Venus.  For more about this conjunction read this article.

The challenge in seeing this conjunction is having a good eastern horizon and looking about 45 minutes before sunrise.  The above chart shows the sky at 45 minutes before sunrise in the Chicago area.

The next Venus-Jupiter conjunction is during the morning of January 22, 2019.  While not a close conjunction, 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.

Figure 6:  Jupiter’s Retrograde loop compared the stars of Libra and Scorpius and the ecliptic.

Because Jupiter moves slowly through its orbit, our planet catches and passes the planet about every year.  The chart above (Figure 6) shows Jupiter’s apparent path among the stars with its retrograde occurring between the Scorpion’s claws.  Scorpius is to the lower left of Jupiter with its bright star Antares.  The green line on the chart represents the ecliptic, the solar system’s plane.

Figure 7:  Detail of the retrograde loop of Jupiter and its triple conjunction with Zubenelgenubi.

Looking closer at the region of the sky where Jupiter appears reveals that it does not have many bright stars.  The chart (Figure 7) shows Jupiter’s apparent motion from November 30, 2017 through October 14, 2018.  Dates on the chart indicate the triple conjunction dates with Zubenelgenubi and Jupiter’s opposition.

Figure 8:  Jupiter in the morning sky with the Claws of the Scorpion.

The first date (November 30, 2017) on the chart (in Figure 7) shows bright Jupiter in the east-southeastern sky with Spica and Mars at 6 a.m. CST.  Jupiter is approaching Zubenelgenubi for the first time with the first conjunction about three weeks away.  Jupiter is about 4.5 degrees to the upper left of its target star (Figure 8).

Figure 9:  Jupiter’s first conjunction with Zubenelgenubi.

By December 21, Jupiter moves eastward to about one-half degree (the apparent diameter of the moon) of the star.  (This was about the same separation when Venus passed Regulus during September 2017 (Figure 9).  See this article for a photo that shows the separation of Venus and Regulus.)

Figure 10:  The Jupiter-Mars conjunction

Jupiter continues to rise earlier each morning.  By New Year’s Day Jupiter rises nearly 4.5 hours before the sun.  On January 7, Mars passes Jupiter (Figure 10).  (Mars is moving faster eastward among the stars than Jupiter.)  In this close conjunction, the planets are separated by only 0.3 degree! Jupiter is nearly 20 times brighter than Mars.  By this morning, Jupiter is nearly 3 degrees past Zubenelgenubi.

The planetary pair is also very close on the previous morning (January 6), only slightly more distant.  Either morning has the two planets close together.

Mars is at opposition on July 27, 2018.  For more information about the two-year appearance of Mars, see this article.  The next conjunction of Jupiter and Mars is March 20, 2020 when the pair is nearly 1 degree apart with Saturn about 7 degrees to the left of the conjunction.

Figure 11:  Jupiter, Mars and the Moon, January 11, 2018

A few days after the Jupiter-Mars conjunction, the moon moves through the region and makes one of its closest passes near Jupiter during this appearance as viewed from the Western Hemisphere.  The waning crescent moon is about 4 degrees from Jupiter (Figure 11).

 

Figure 12:  Jupiter reaches its western quadrature (90 degrees from the sun) on February 10, 2018.

As Earth moves toward Jupiter, Jupiter and the nearby stars appear slightly higher each morning, noticeably higher in week.  By February 10, Jupiter rises around midnight and appears in the south as dawn approaches.  It is at quadrature, 90 degrees from the sun (Figure 12).  The westward march of the celestial sphere continues.

Figure 13:  Jupiter stops moving eastward and begins to retrograde, March 8, 2018.

On March 8, 2018, Jupiter appears to stop moving eastward and appears to move backward compared to the starry background.  At this time Jupiter is 8 degrees from Zubenelgenubi and the moon is 13 degrees to the left of Jupiter (Figure 3).

Jupiter in the Evening Sky

Figure 14:  Jupiter reaches opposition on May 8, 2018 and appears in the sky all night.

As the mornings pass, Earth catches up to and moves between Jupiter and the sun on May 8, 2018 (opposition).  Jupiter is about 400 million miles away.  Its large size and highly reflective clouds make it gleam in our night sky.

At opposition, Jupiter rises in the southeast at sunset and moves westward during the night from our planet’s rotation.  By midnight it is in the south and it sets in the southwest at sunrise (Figure 14).

 

Figure 15:  Jupiter’s second conjunction with Zubenelgenubi, June 3, 2018

After opposition, Jupiter rises before sunset and shines from the southeast as the sky darkens.  By early June, Jupiter rises nearly 2.5 hours before sunset, shining from the southeast as night falls.  After opposition, Jupiter continues to retrograde.  By June 3, it passes Zubenelgenubi again for the second conjunction by nearly one degree (two apparent full moon diameters — Figure 15).  Extend an arm and your index finger on that hand.  Your finger will nearly cover both the planet and the star; that’s one degree.

Figure 16:  This chart shows Jupiter setting in the western sky compared to the time of sunset.

Jupiter continues to appear farther to the west each evening at sunset,  By early July it begins setting 5 hours after sunset; it is graphed on the setting chart as displayed above (Figure 16).  The chart shows the stars, planets, and moon setting in the west after sunset with the three phases of twilight.

Figure 17:  Jupiter stops retrograding on July 17, 2018

After Earth passes Jupiter, it stops retrograding and resumes its eastward motion against the sidereal backdrop.  The chart  (Figure 17) shows Jupiter in the south-southwest at around 10 p.m. on July 17.  Jupiter is setting earlier each night; it is beginning a very slow fade into the western sky that lasts until November.  Jupiter and Zubenelgenubi are now about 2 degrees apart.

 

Figure 18:  Jupiter appears at its eastern quadrature in the evening sky on August 6, 2018

By August, Jupiter rises during the day and is in the south at sunset.  On August 6, Jupiter and the sun are 90 degrees apart in the sky (Figure 18).  And this Giant Planet sets about 3.5 hours after sunset.

Figure 19:  Jupiter passes Zubenelgenubi for the third conjunction during the planet’s apparition, August 16, 2018.

The third conjunction with Zubenelgenubi occurs on August 16 when Jupiter passes about 0.5 degree above the star (Figure 19).  The triple conjunction is now complete in one Jupiter apparition.

Figure 20:  Venus and Jupiter appear in the western sky, but there is no conjunction.
This chart shows them 16 degrees apart.

By late summer Jupiter appears near brilliant Venus which is completing its 2018 evening apparition.  On the setting chart above (Figure 16), Venus sets about 2 hours after sunset — at the end of twilight on July 7 — while Jupiter sets over 3 hours later.  As the weeks progress, Jupiter sets earlier and Venus continues to set around 2 hours after sunset.  A conjunction looks imminent, but Venus then quickly dips into the sun’s blinding glare.  The chart above shows Jupiter and Venus on September 15 when Venus sets about an hour after sunset (Figure 20).  The pair is 16 degrees apart.  They get as close as about 14 degrees, but Venus is setting during bright twilight.

 

Figure 21:  Jupiter fades quickly into the western horizon.  This is the last date
charted on the retrograde charts earlier in this article.

The retrograde charts (Figure 6 and Figure 7) show the last plotted date as October 14.  On this day Jupiter sets about 90 minutes after the sun.  At the chart time above, Zubenelgenubi and Zubenelgenubi are low in the western sky.  (Likely Zubenelgenubi is visible only through binoculars and telescopes when viewed with a clear horizon).  Jupiter is about 9.5 degrees past its point of triple conjunction and nearly 16 degrees west of Antares (Figure 21).

Jupiter is on course for a 2020 conjunction with Saturn.  On this chart (Figure 21) these planets are 38 degrees apart.  Conjunctions between these two planets are infrequent.  After 2020, the next conjunction is November, 2040.  The last one was May 2000.

Jupiter revolves around the sun every 11.8 earth years; Saturn revolves every 29.5 years.  Because each move slowly around the sun, it takes Jupiter about 20 years to catch Saturn.  (In 1981 there  was a triple conjunction of the two planets!)

 

Figure 22:  Jupiter reaches its solar conjunction on November 26, 2018.

Jupiter slowly disappears into bright sunlight and heads for conjunction on November 26, 2018 (Figure 22), completing its 2017-2018 appearance and triple conjunction between the Claws of the Scorpion.

Watch Jupiter slow creep eastward and catch a slower moving Saturn during the next few years.

Appearances with the Moon

Jupiter appears with the Moon on these dates (Central Time):

Before Opposition

  • November 16, 2017 — 6 degrees (d)
  • December 14, 2017 — 4d
  • January 11, 2018 — 4d
  • February 8, 2018 — 6d
  • March 7, 2018 — 3.5d
  • April 3, 2018 — 6d
  • April 29, 2018 — 5.5d

After Opposition

  • May 27, 2018 — 6d
  • June 23, 2018 — 4d
  • July 20, 2018 — 3.5d
  • August 18, 2018 — 7.5d
  • September 13, 2018 — 4d
  • October 11, 2018 — 3d
  • November 8, 2018 — 3d (during bright twilight

Conclusion

Jupiter, a gleaming celestial gem, can be seen shining among the dimmer stars of Libra, nearly midway between Spica and Antares.  During this appearance it has a triple conjunction with Libra’s brightest star Zubenelgenubi, Venus and Mars. During 2018 Jupiter and Venus have a far encounter when they are about 14 degrees apart.  Take a look at the movement of Jupiter compared to the starry background and as it starts in the eastern morning sky and then disappears into the sun’s glare in late 2018.  Watch the distance between Jupiter and Saturn close during the next few years for their infrequent celestial conjunction.

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2017, August 7: Jupiter and Saturn

Jupiter appears in the western sky this evening.  It appears lower in the sky each evening as it is heading toward its solar conjunction.  It appears near Spica, but the star is hidden by the trees in the image above.  Spica is about 7 degrees to the lower left of Jupiter this evening.  Jupiter is heading toward its final conjunction with Spica in this triple conjunction appearance.

Meanwhile, Saturn — the Ringed Wonder — is in the southern sky.  It is about 13 degrees to the upper left of the star Antares.

Jupiter is slowly moving toward Saturn for a 2020 conjunction.  Tonight the pair is over 60 degrees apart.  Conjunctions of Jupiter and Saturn are uncommon.  They occur in intervals of about 20 years.  During the 2020 conjunction the two planets appear about 0.1 degree apart on December 21.

For more information about sky watching events:

2017, August: Saturn

Saturn appears in the southern skies during the early evening hours of August 2017.  On August 2, the waxing crescent moon appears about 4 degrees to the upper right of Saturn with the reddish star Antares nearly 13 degrees to the lower right of Saturn.  Saturn is distinctly yellow-orange in color and slightly brighter than Antares.

Later in the month, the moon passes Saturn again.  On the evenings of August 29 and 30, the moon appears about 6 degrees from the planet.  On the first night the moon is the upper right of Saturn on the next evening it is to the upper left of Saturn.

For more information about sky watching events:

 

2017, July: Saturn

Saturn, the Ringed Wonder, is low in the southeastern sky after sunset.  While not a spectacularly bright planet, it is a spectacle through a telescope.

The nearly full moon passes 2.5 degrees above Saturn on July 6.  The reddish star Antares is 14 degrees to the right of Saturn.

For more information about sky watching events:

2017-2019: Mars Observing Year with a Perihelic Opposition, July 27, 2018

Update:  Venus and Mars in the morning sky, October 16, 2017.

Photo Credit:  NASA

Every few years, Earth passes Mars. The Red Planet shines brightly in our skies, and prompts many Internet claims that the planet will appear larger than the moon.


Photo credit

In recent history observations of Mars spawned stories of great martian cities and unusual beings.  Mars is a planet that inspires intrigue and speculation.

Once every 15 or 17 years, Mars appears at opposition when it is nearest the sun (perihelion).  Just after midnight (12:13 a.m. Central Daylight Time) on July 27, 2018, opposition occurs and this is near Mars’ closest point to the sun (perihelion).  Opposition is just not one flash-in-the-pan event.  During the evenings leading up to opposition, the Mars grows in brightness and in size, although its planetary globe is not discernible to normal human sight.  A telescope is needed to see the orb of Mars.  More about the appearance of Mars during its 2017-2019 observing year follows.

Morning Appearance

The 768-day observing season begins with Mars’ solar conjunction on July 26, 2017 (7:57 p.m. CDT).

At this time, Mars is behind the sun as viewed from Earth and lost in the sun’s brilliance.  It rises with the sun, lies in the south at noon, and sets around sunrise.  The planet gradually emerges into the morning sky.  This process is slower than most planets as it revolves around the sun every 687 days about half the speed of our planet.

On the chart above notice the scale drawings of the planets’ orbits.  Earth’s orbit is nearly a circle, while Mars’ orbit is more elliptical.  Opposition occurs nearly a year after the conjunction date.   The planets are over-sized on the chart to easily demonstrate their positions.  The yellow line that extends from Earth through the sun defines noon, the morning side of the sky and the evening sky.  The line pointing away from the sun, defines midnight.

This chart was calculated from data by the United States Naval Observatory for Chicago, Illinois, in the Central Time Zone.

The chart shows the rising time of Mars (the red line) compared to sunrise beginning with its solar conjunction (7/26/17) until the time it rises more than 5 hours before the sun (May 23, 2018). The rising time differences for the moon (circles) and other bright planets are included as well as the rising time differences for bright stars that appear near the plane of the solar system (ecliptic) where the planets appear to move in the sky.  The time differences are included for Civil Twilight, Nautical Twilight and Astronomical Twilight.  These events occur in the eastern sky, except for the Saturn sets and Jupiter Sets circles.  Those planets are setting in the morning western sky.

Mars is hidden in the sun’s glare until late August, although it can be found with optical assistance.  Mars appears near a celestial object when its rising line crosses other celestial objects’ rising lines or when the Mars rising line appears near a circle indicating the rising of the moon.  During this morning appearance, the Red Planet has conjunctions with Mercury, Venus, Spica, Jupiter, Antares and Saturn.

As it rises and sets from Earth’s rotation, it rises earlier each morning from our revolution around the sun and its revolution around the sun.  At its solar conjunction we are 180 degrees from Mars and are moving nearly twice its speed, so it’s a slow catch-up game.  Meanwhile the other celestial objects rise earlier from our revolution around the sun, except for Mercury, the moon and Venus.

Mars-Mercury Conjunction

As Mars emerges from the sun’s glare, it is dim in our skies.  In late August and early September it appears near Regulus, Mercury. Venus and the moon.

On the morning of September 16, Mars and Mercury appear very close together, less than 0.2 degrees apart!  The pair is only 17 degrees from the sun and near the horizon when the sky begins to brighten.  Mars is over 240 million miles away, appearing as a not-so-bright star in the morning sky.

Our view on this morning puts Mercury and Mars, in conjunction, near the eastern horizon with Regulus 7 degrees above Mars with Venus and the waning crescent moon higher in the sky.  Find a clear horizon and use binoculars.  This view shows them one hour before sunrise, about the time of nautical twilight, when the horizon is first distinguishable.

Update:  September 18, 2017

Venus-Mars Conjunction

Mars and Venus were last in conjunction on November 3, 2015 when they were about 3/4 degree apart.  As with the last conjunction the 2017 conjunction occurs in a sky full of planets as noted here.  Also note that these conjunctions occur farther east along the solar system’s (ecliptic) plane.

As Venus heads toward its solar superior conjunction, it passes Mars on the morning of October 5.  On the rising chart above notice that the Venus rising time(the green line) diminishes during the autumn of 2017.  Mars’ separation from the sun has grown to 23 degrees.  Earth is slowly catching Mars, yet opposition is months away.  From this scale drawing notice that Venus’ orbit is closer to Earth than Mars.

The separation of the pair is about one-fourth of a degree.  This would be spectacular conjunction if Mars were brighter.  However, Venus-Mars conjunctions only occur when Mars is far away from our planet and near the sun (where Venus appears).  For more about the appearance of Venus, see this article.  The planets are close for a few mornings before and after this close passing.

Update:  The Venus-Mars conjunction, October 5, 2017

The moon moves through its orbit about every 27 days and its cycle of phases nearly every 30 days.  The circles on the chart indicate the rising times of the moon.  If a moon circle appears near a planet or star on the chart, there is a good chance they are together in the sky.  For example on October 17, the moon circle appears with Mars and Venus (the green line) rises less than an hour later.

The view of that morning is a close appearance of the waning crescent moon and Mars (1.3 degrees) with Venus 7 degrees to the lower left of Mars.

Mars-Spica Conjunction

Mars then slowly lumbers eastward compared to the starry background, moving eastward along the solar system’s ecliptic plane.  Earth is slowly catching up to the Red Planet and it has brightened only slightly since its first morning appearance.


On the morning of November 30, Mars passes slightly more than 3 degrees from the star Spica. The pair is close for a few days before the closest pairing.  Jupiter began its morning appearance in late October is now about 16.5 degrees to the lower left of Mars.  Watch Mars catch up with Jupiter during the next six weeks as the two pass early in 2018.

Jupiter-Mars Conjunction

By early 2018, Mars is now nearly 60 degrees from the sun, rising about 4.5 hours before sunrise, nearly 45% brighter than when it first appeared in the morning sky, and about 180 million miles from Earth.  Earth is slowly catching.  Recall, that Mars moves at about half the speed of Earth, so it’ll over six months to catch Mars from this point.

On a few mornings around January 7, 2018, Mars passes close to Jupiter near the stars of Libra with the star Antares nearly 23 degrees to the lower left of the planetary pair.  Jupiter is over three times farther away than Mars, yet it outshines the nearer planet by 20 times.  Jupiter’s brightness is from its enormous size compared to Mars and its highly reflective cloud tops.  Jupiter’s clouds reflect nearly 40% more sunlight than Mars’ rocky and dusty surface.  Since it is over 3 times farther away than Mars early in the new year, it receives only 11% of the sunlight that reaches its red neighbor.  Jupiter is highly reflective and much larger, yet it receives much less sunlight than Mars.

Future Jupiter-Mars Conjunctions

Jupiter and Mars are in conjunction in spans of 26-27 months.

The next conjunction is March 20, 2020 when the two planets are about 0.7 degree apart when they rise in the morning sky before the beginning to twilight.  A close conjunction occurs (0.3 degrees) on August 14, 2024 when the two planets rise in the northeastern sky after 1:30 a.m.  The conjunction occurs among the bright stars of Taurus  near Aldebaran and the Hyades.  A conjunction slight closer than the 2018 conjunction (0.2 degree) occurs on December 1, 2033.  The planets appear in the evening sky in front of the dim stars of Aquarius, setting at about 10:30 p.m.

Mars-Antares Conjunction

During the next 30 days, Mars continues to ramble eastward among the stars and growing nearly 40% in brightness.  On the morning of February 10, Mars passes 5 degrees from the star Antares.  Jupiter is 17 degrees to the upper right of Mars and the waning crescent moon is 14 degrees to the lower left.  Mars is the Roman name for this planet.  The Greeks called it Ares.  Antares is sometimes called the “Rival of Mars.”  When are both are in the sky the resemble each other in brightness and color.  Another way to consider this is the prefix “Ant,”  sometimes meaning against: Antares = Against Mars.  Yet another way is to think that “Ant” can be replaced with “Not:” Not Mars.  This star is Antares, not Mars; it’s not Mars.

Mars at Quadrature West

By late March, Mars is well past Jupiter with an upcoming conjunction with Saturn, yet still in the morning sky.  It has grown in brightness nearly 2.5 times since the beginning of the year.  On March 23, it is 90 degrees from the sun (quadrature), rising about four hours, twenty minutes before sunrise and shines from the southern skies at sunrise.  Earth is beginning to approach Mars, still 110 million miles away, but the opposition is still 3 months away.

Mars-Saturn Conjunction

Mars continues eastward march against the starry background, reaching Saturn on April 2, 2018 when the two planets are about 1.25 degrees apart.  The Red Planet is slightly brighter (about 23%) than Saturn.  The color contrast is distinct, with Saturn’s pale yellow-orange color distinguished from Mars’ red-orange hue.  This conjunction occurs north of the main stars of Sagittarius, also commonly called “The Teapot.”

Mars Retrograde

After the Saturn conjunction, Mars continues to move eastward compared to the stars, yet it rises in the east and sets in the west as Earth rotates.  It moves away from the region of the Tea Pot toward the stars of Capricornus.  On June 26, Mars stops its eastward motion among the stars and begins to appear to move backwards, retrograde.  Since its conjunction with Saturn, this brightness grows over times and its distance diminished 2.5 times.  For the next month, Mars continues to retrograde as it reaches opposition, rising in the east at sunset and setting in the west at sunrise.  Its brightness grows another 20%.  Because Mars’ orbit is noticeably elliptical, opposition night is not the closest night.  Four nights later Mars is closest it has been since August 28, 2003.

This chart shows the close opposition of Mars.  The planet orbits are to scale, the planet sizes are not to scale.  Mars appears as a bright star at opposition.  (It will not appear the size of the moon.)  The “midnight” indicates that Mars is south at midnight, opposite the time when the sun is south.

On Opposition night the full moon appears about 7 degrees from Mars as they rise in the east at sunset.  On the evenings around opposition, Mars outshines all other stars and planets except Venus, although the moon is 10000 times brighter than Mars.

Other close historic perihelic oppositions:

  • August 10, 1971, 0.376 A.U. (1 A.U. is about 93 million miles, the average earth-sun distance)
  • August 18, 1845, 0.373 A.U.

The next perihelic opposition is September 15, 2035 (0.382 A.U.).  The next Mars opposition is October 13, 2020 (0.42 A.U.).  A more extensive list of oppositions appears at the end of this article.

Mars continues to retrograde until August 27, dimming slightly as it moves westward motion against the stars.

Resuming its eastward motion, Mars dims considerably, nearly 2.5 times as our planet now moves away from it as the last date displayed on the chart is displayed (October 13, 2018).

For more details about the opposition, see this article.

Mars in the Evening Sky

After opposition, Mars is in the eastern sky during the early evening, in the south in the middle of the night and setting in the west well before sunrise.

On December 1, 2018, as Earth pulls away from Mars, it is 90 degrees east of the sun, now in the evening sky.  (The angle Sun-Earth-Mars angle is 90 degrees.)  It appears in the southern sky around sunset.

On New Years Day 2019, Mars is in the southern sky after sunset and setting in the west around midnight.

In early March 2019, Mars “appears” on the evening sky chart showing when planets, the moon (circles) and bright stars near the ecliptic set after sunset.  This chart refers to activity in the western sky after sunset.  The Jupiter rises and Saturn rises circles refer to activity in the eastern evening sky.

Mars continues to move eastward compared to the stars, now much dimmer than it was a few months ago.  On the evening of March 11, 2019, the moon appears about 7 degrees to the upper left of Mars.

On March 31, 2019, its eastward motion carries it near the Pleaides star cluster and its brightest star Alcyone.  Away from bright lights, Mars is easily distinguishable from the tiny star cluster.

Through binoculars, the stars cluster stands out.  The contrasting colors of the stars with Mars is easy to see.

During Spring, Mars continues to set earlier each night as it slowly ambles eastward against the stars. By May it is 30 times dimmer than it was at opposition.  While it is one of the brighter celestial objects, Earth is pulling away from Mars making it appear dimmer in our sky.  On May 7, Mars appears near several brighter stars that are prominently displayed in the southern sky during the evening hours of winter.  The moon is 3.75 degrees to the lower left of Mars.  Prominent Betelgeuse, Aldebaran, and Elnath appear in the same region.

Mars begins setting during twilight in early June 2019.  On June 18 Mercury passes 0.2 degree from Mars.  Mercury is over 1.5 times brighter than Mars, yet the Red Planet is over 230 million miles away heading toward its solar conjunction.

Mars setting earlier during twilight each evening becoming a binocular object as it sets in deeper twilight.

As it sets in bright twilight, it passes Pollux and Regulus.  In late August 2019, Venus and Mars pass each other, but the pair sets about 10 minutes after sunset.

Mars reaches its solar conjunction on September 2, 2019, again rising with the sun, is in the southern noon sky, setting in the west with the sun, and ending its 768-day apparition with its perihelic opposition.

Mars Appearances With the Moon

Morning Appearance (Can be seen in the sky before sunrise)

  • August 20, 2017, 8 degrees (d) separation(During twilight)
  • September 18, 2017, 4 d

  • October 17, 2017, 1.3 d (See text)
  • November 15, 2017, 5.5 d
  • December 13, 2017, 4.75 d
  • January 11, 2018, 4 d
  • February 9, 2018, 4.3 d
  • March 10, 2018, 5.75 d
  • April 7, 2018, 4.2 d
  • May 6, 2018, 2.5 d
  • June 3, 2018, 2.3 d
  • July 1, 2018, 6 d

Evening Appearance (Can be seen in the sky after sunset)

  • July 27, 2018, 7 degrees (d) separation  (Opposition Night!)
  • August 23, 2018, 8 d
  • September 19, 2018, 4.25 d
  • October 17, 2018, 5.25 d
  • November 15, 2018, 2.3 d
  • December 14, 2018, 4 d
  • January 12, 2019, 5.3 d
  • February 10, 2019, 6.25 d
  • March 11, 2019, 7.3 d (See text)
  • April 8, 2019, 6.5 d
  • May 7, 2019, 3.75 d (See text)
  • June 5, 2019, 6 d
  • July 3, 2019, 2.75 d
  • August 1, 2019, 2.3 d (twilight)

Future Mars Oppositions

  • October 13, 2020
  • December 7, 2022
  • January 15, 2025
  • February 19, 2027
  • March 25, 2029

A perihelic opposition occurs July 27, 2018.  This close oppositions provides an infrequent opportunity to watch Mars emerge from behind the sun climb into the eastern morning sky.  It gradually increases in brightness to brightly appear at opposition.  Then it slips back into the bright twilight of the sun to complete its dramatic close appearance.

“Imagination is but another name for super intelligence.” — Edgar Rice Burroughs

2017, June: Saturn at Opposition

The Ringed Wonder reaches opposition on the morning of June 15.  At this time our planet is between Saturn and the sun.  On the evenings around opposition, Saturn rises in the opposite direction from the sunset point.  As Earth rotates, it rises higher in the sky each hour.  At midnight it is in the southern sky.  From that time, the planet begins to appear lower in the sky, setting in the southwest as the sun rises in the northeastern sky.

On the evening of June 8, the waning gibbous (just past full) moon appears nearly 3 degrees to the upper left of Saturn.  The reddish star Antares is nearly 16 degrees to the upper right of Saturn.

This is the last opposition of naked eye planets this year.

The three outer planets, which includes Pluto, have oppositions this year, but they are only observed with optical assistance:

  • Pluto,  July 10
  • Neptune, September 5
  • Uranus, October 19

Observers are interested in oppositions because at this time, the planet at opposition is closest to Earth and so the planet’s observable features are easiest to see through telescopes.  The planet is in the sky all night and highest in the sky at midnight.

Photo credit:  Lowell Observatory

During an 1894 Mars opposition, Percival Lowell first began to document his later disproved discovery of “canals.”  While remote satellites give close-up images of the distant worlds, there are few more memorable events than seeing Jupiter, Saturn or Mars through a telescope.

In 2018, the three naked eye outer planets appear at opposition within an 80-day period:

  • Jupiter, May 8
  • Saturn, June 27
  • Mars, July 27

As they emerge from their solar conjunctions later in the year, they appear with Venus in the morning sky, including another Venus-Jupiter Epoch Conjunction.  More about these events as they approach.

For more information about sky watching events:

2017, May: View of Saturn

Saturn rises in the May sky later in the evening.  Early in the month it appears above the eastern horizon around 10 p.m.  While this planet does not dominate the sky in brightness, it is on of the wonders of the sky through a telescope.  Its extensive rings dazzle the eye.

On the morning of May 14, the waning gibbous moon appears about 4.5 degrees from Saturn.  The star Antares, appears 17 degrees to the upper right of Saturn.

On May 1, look for Venus near the eastern horizon, Jupiter near the western horizon and Saturn in the south.

For more information about the planets see: