2017, September 18: Venus, Moon, Mercury and Mars

Brilliant morning star Venus is joined by the 28-day-old moon this morning. The star Regulus appears about 1.5 degrees below the bright planet. Elusive Mercury appears low in the sky. It is easily viewed without binoculars. Dimmer Mars about 1.5 degrees above Mercury and it is emerging from the sun’s glare. It appears near Venus on October 5th.  (Click the image to see Mars easier.)

Notice the earthshine on the moon.  The night portion of the lunar surface is gently illuminated by reflected sunlight from our planet.

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2017, September 15: Venus, Mercury, and Mars

Venus, Mercury and Mars appear in the predawn skies this morning.  Brilliant Venus continues to dominate eastern sky before sunrise.  The star Regulus appears about 5.5 degrees to the lower left of Venus.  Elusive Mercury appears low in the sky.  The image above demonstrates the need for a clear horizon when looking for Mercury.  Mars, currently dim, appears about 1 degree to the lower left of Mercury.  Click the image to see Mars.  The Red Planet is slowly emerging from the sun’s glare.  Venus and Mars are in conjunction on October 5.

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2017, September 11: Venus and Mercury

Brilliant Venus continues to dominate the predawn eastern skies during late summer.  Elusive Mercury appears low in the sky as dawn approaches.  For the next few mornings it appears near the star Regulus.  (Click the image to see Regulus and Mercury.)  As in this indicated in this image, find a clear horizon to see Mercury.  Binoculars help find the planet.  Mercury rises about 1.5 hours before sunrise, about the time that morning twilight begins.

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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, March 28: Mercury and Mars

After several days of rainy and cloudy weather in the Chicago area, clear skies prevail this evening as Mercury begins its best evening display of the year.  At about 45 minutes after sunset Mercury stands less than 10 degrees above the horizon, so a clear viewing spot is needed.  Mars is nearly 17 degrees to the upper left of Mercury.

Tomorrow evening (March 29), the crescent moon joins the planetary pair.  If you can’t find Mercury, the moon is a guide with binoculars:  Mercury is about 9 degrees to the lower right of the moon.  In typical 7 x 50 binoculars, Mercury stands just outside the field of view if the moon is placed at the 10 o’clock part of the field.  Slowly move the binocular toward the 4 o’clock direction.  Mercury will appear in view.

Link to YouTube video.

For more information about Mercury’s evening appearances this year, see this article:

For more information about current sky events, see these articles:

2017: Mercury’s Spring Evening Appearance

Mercury’s best evening appearance at mid-northern latitudes occurs during spring evenings.  This year, Mercury appears farthest from the sun on April 1.  A few days earlier (March 29), the moon helps in locating this speedy and elusive planet.  Look to the west at 8 p.m. CDT as observed from the Chicago area.  For other time zones, look about 45 minutes after sunset.  The crescent moon stands nearly 13 degrees above the western horizon.  Mercury is about 9 degrees to the lower right of the moon.  In typical 7 x 50 binoculars, Mercury stands just outside the field of view if the moon is placed at the 10 o’clock part of the field.  Slowly move the binocular toward the 4 o’clock direction.  Mercury will appear in view.

Mars is fading in brightness quickly and appears 11 degrees above the moon.

Link to YouTube video.

For more information about Mercury’s evening appearances this year, see this article:

For more information about current sky events, see these articles:

2017, Late March: Venus as a Morning and an Evening Star

This is likely visible only with optical assistance, such as through binoculars or a small telescope.  WARNING!  NEVER POINT BINOCULARS OR TELESCOPE DIRECTLY AT THE SUN!   Such activity can cause permanent damage to your vision and/or the optical device.

As Venus rapidly disappears into the sun’s brightness during the next few weeks of March, it is visible in the morning sky and evening sky with optical assistance.  (Not to be redundant, but heed the warning above.)

Venus reaches inferior conjunction on March 25, 2017.  At this time Venus moves between the Earth and the sun.  Because the orbits  of the planets line nearly in a plane, but not a perfect one, Venus does not move directly across the face of the sun.  It either passes above or below the sun.

At this conjunction, Venus is about 8 degrees above or north of the sun.  When an object is north of the sun, it can appear in both the morning and evening sky.  The Big Dipper is far north of the sun.  In March, during the early evening from mid-northern latitudes, the Big Dipper appears to stand on its handle high in the northeast.  In the predawn hours, it appears to be dipping down from the northwestern sky.  The Big Dipper is an extreme case of the concept.  But is shows that anything north of the sun can be both seen in the morning sky and in the evening sky,

The chart above (click the image to see it larger), shows Venus’ invisible orbit at noon on inferior conjunction day.  With appropriate shading, the planet is visible with optical assistance.  It is north of the sun.

Starting at mid-March and until inferior conjunction, Venus rises just ahead of the sun in the morning and sets just after it in the evening, during bright twilight, and so the need for optical assistance.  The optimum date is March 22 when Venus rises about 30 minutes before the sun and sets 30 minutes after.

At 6:45 a.m. CDT in the Chicago are (check your local sunrise time for other locations), about 10 minutes before sunrise, Venus stands 4 degrees above the the horizon and about 11 degrees from the sunrise point.  A crescent moon is in the southeast, over 70 degrees from Venus and not much help with its identification.

That evening, about 15 minutes after sunset (7:10 p.m. CDT in the Chicago area), Venus is 4 degrees above the horizon and 8 degrees from the sunset point.  Dimmer Mercury is about 13 degrees to the upper left of Venus.

While not easily seen, it is possible to see Venus as both a morning and evening star.

For more information about current sky events, see these articles: