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: Jupiter

Jupiter appears in the western sky during the early evening hours of August 2017.  It is heading toward its solar conjunction on October 26, 2017.  It reappears in the morning sky with an Epoch Conjunction with Venus on November 13, 2017.

During this appearance, Jupiter is preparing to pass Spica for a third time on September 5.  More about this in the links below.

On the evening of August 25, the crescent moon passes Jupiter and Spica.  The moon is 5.5 degrees to the upper left of Jupiter with Spica 4 degrees to the lower left of Jupiter.

For more information about sky watching events:

 

2017, November 13: An Epoch Venus-Jupiter Conjunction

The Epoch Venus-Jupiter Conjunction, August 27, 2016

An Epoch Conjunction

A Venus-Jupiter Epoch (close) conjunction occurs 443 days after the last conjunction of these two bright planets shown in the image above.  This conjunction occurs just before sunrise on the morning of November 13, 2017 when the two planets are about 0.3 degrees apart. 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.

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 (this includes 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 47 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.

The Conjunction

From the above chart notice that Venus is a brilliant Morning star for most of 2017.  During the autumn it sets earlier compared to sunrise.  It is heading toward its superior conjunction with the sun on January 9, 2018.  Jupiter reaches its solar conjunction on October 26, 2017.  It is behind the bright sun.  Jupiter slowly emerges into twilight and then begins rising before morning twilight begins.  The November 13th conjunction occurs during twilight.  It is not impossible to view.  Two factors are important:  Having a clear eastern horizon and viewing the pair before the sky grows too bright.  The pair is only 14 degrees west of the sun and 5 degrees above the horizon, making the view a little tricky.

Unlike other recent Venus-Jupiter conjunctions, showing events leading up to the conjunction are limited by Jupiter’s solar conjunction that occurs only 18 days before this epoch meeting.  Further Venus is headed for its solar superior conjunction and rapidly plunging into the solar glare.  Our lead-up and follow-up descriptions are limited by the sun’s glare.

The views on the charts below are 40 minutes before sunrise, 6 a.m. CST in the Chicago, Illinois region.  Check your location for the sunrise time and look for the planetary pair 40 minutes before sunrise.

Brilliant Venus and bright Jupiter shine from low in the east-southeastern sky.  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.

This chart shows the relative sizes of the planet orbits for the conjunction.   The sizes of the planets have been exaggerated to see them.  The angle the planets make with the sun is only 14 degrees making them appear low in the eastern sky.  At the time of the conjunction, Jupiter is nearly 4 times farther away than Venus.

On conjunction morning, the pair is still very low in the east-southeastern sky.  They are about 1/3 of a degree apart!    Spica is 13.5 degrees to the upper right of Venus; Mars is nearly 24 degrees above Venus; and the moon is 43 degrees above Venus.

Through a telescope, Venus and Jupiter appear in the same field of view.  The Galilean Satellites, the four large moons, line up with Jupiter’s cloud bands.  Two appear  above Jupiter and two below.  Depending on the optical configuration of the telescope, Venus is visible to the side of Jupiter.

On the morning following the conjunction, Venus and Jupiter are over a degree apart.  Spica is 14.5 degrees to the upper right of Venus; Mars is 24 degrees above the bright planet; and the moon is 31 degrees above Venus.  The moon is 11 degrees above Mars.

For more about the appearances of Venus and Mars, see these articles:

Upcoming Venus-Jupiter Conjunctions

The table below shows the next 6 Venus-Jupiter conjunctions.  The February 2025 event rival this conjunction in separation.   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
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.
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.
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.

2017, July: Jupiter

Jupiter is that bright “star” in the southern skies at sunset.  The moon appears with it twice during July.  On July 1, the waxing crescent moon is 9 degrees to the upper left this Giant Planet.  The bluish star Spica is about 10.5 degrees to Jupiter’s lower left.

Early last month Jupiter began moving eastward again compared to the stars and it appears to be moving toward Spica.  Watch it approach Spica during the month.

 

On

On July 28, the moon is about 3 degrees to Jupiter’s upper left with Spica about 8 degrees to the lower left.  The change in Jupiter’s position is easily seen when comparing it to Spica’s “fixed” place on the sidereal sphere.

For more information about sky watching events:

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

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.

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.

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: Jupiter in Evening Sky

Jupiter is the bright “star” in the southern sky during the early evening hours this month. On June 3, the waning gibbous moon appears about 2 degrees to the upper left of the giant planet.  Spica appears 11 degrees to the lower left of Jupiter.  The constellation Corvus the Crow is nearby.

Jupiter ends its retrograde motion on June 8th and begins to move eastward again as compared to the sidereal background.  It slowly appears to move toward Spica, passing on September 5.

For more information about sky watching events:

 

2017, May 11: Jupiter, Spica & Big Dipper

Jupiter shines in the southeastern sky during the early evening hours near the star Spica.  Jupiter is about 10 degrees to the upper left of the star and the planet is over 20 times brighter.  The giant planet continues to retrograde for about another month.  (For details see the link at the bottom of this posting.)  Through binoculars, up to four of Jupiter’s largest moons might be visible.  The constellation Corvus is nearby.  It consists of four stars that make an irregular box.

Meanwhile the Big Dipper is nearly overhead during the early evening hours of May.  Its famous double star, Mizar and Alcor are visible.

For more information about the planets see: