2018, March 18: Venus, Mercury and the Moon

Venus enters the evening sky early in 2018, setting later each night.  By March 1 Venus sets about 100 minutes after sunset, although before the end of twilight . Mercury has its best evening appearance with its greatest elongation on March 15.  On March 18, Mercury passes about 4 degrees from Venus with the moon 4 degrees beyond Venus.  The moon is just 35 hours past its new phase.

After the conjunction, Venus continues to set later; by the end of the March, it sets after twilight ends.  Mercury dashes back into the sun’s glare toward its inferior conjunction on April 1, reappearing in a difficult-to-see apparition in the morning sky.

The articles that follow provide details about the planets visible without optical assistance (binoculars or telescope):

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2018: The Evening Sky

This article summaries the planetary activity in the evening sky during 2018.  The articles that follow provide details about the planets visible without optical assistance (binoculars or telescope):

The chart shows the setting of planets, stars, and the moon (circles) compared to sunset.  This occurs in the western sky.  The three phases of twilight are graphed as well.

Conjunctions are displayed with squares.  Yellow triangles and the letters “GE” show the greatest elongation of Mercury or Venus.  A yellow diamond with the letters “GB” indicate the interval of Venus’ greatest brightness.

The rising of Mars, Jupiter, and Saturn are displayed.  This occurs in the east.  The opposition dates of those planets are also indicated.

It is important to emphasize that the chart shows setting times.  When the setting lines of two objects cross, it indicates that they set at the same time.  Because we have chosen planets and stars along the ecliptic, the virtual path along which the sun, moon and planets appear to move along, they can appear at conjunction or near each other.   This can occur within a few days of the date of coincident setting.  For the purposes of the chart, the conjunction is indicated on the setting time curve of the brighter planet.  Sirius, the brightest star in the night sky, sets at about the same time as Aldebaran in Taurus.  The stars, though, are 46 degrees apart in the sky.  Sirius sets in the southwest and Aldebaran sets in the west-northwest.

The charts below summarize some of the evening events during the year.  This includes oppositions of Jupiter, Saturn, and Mars.  Just before the opposition of Mars, the five naked eye planets can be seen at once.  Observers at more southerly latitudes see this event easier.

Jupiter and Venus do not have a conjunction.  At the end of September the planets are closest at 14 degrees.

 

2018: The Morning Sky

This article summaries the planetary activity in the morning sky during 2018.  The articles that follow provide details about the planets visible without optical assistance (binoculars or telescope):

The chart above shows the rising times of the planets, stars near the plane of the solar system, and the moon (circles) compared to the time of sunrise.  The chart is drawn for Chicago, Illinois in the U.S.A. Central Time Zone from data from the U.S. Naval Observatory.  The three phases of twilight are displayed as well.  The activity generally displays activity in the eastern sky, except for the setting lines for Jupiter, Saturn and Mars.  These three planets set in the western sky; their setting times are compared to sunrise.  Each is at opposition during 2018:  Jupiter, May 8; Saturn, June 27; and Mars, July 27.  When at opposition, Earth is between the sun and one of those planets.

The three naked eye outer planets — Mars, Jupiter, and Saturn — are displayed when they are set in the west during the morning.

It is important to emphasize that the chart shows rising times.  When the rising lines of two objects cross, it indicates that they rise at the same time.  Because we have chosen planets and stars along the ecliptic, the virtual path along which the sun, moon and planets appear to move along, they can appear at conjunction or near each other.   This can occur within a few days of the date of coincident setting.  For the purposes of the chart, the conjunction is indicated on the rising time curve of the brighter planet.  Betelgeuse, the reddish-orange star at Orion’s  shoulder, rises at about the same time as Castor in Gemini.  The stars, though, are 33 degrees apart in the sky.  Betelgeuse rises in the east and Castor rises in the northeast.

The white squares on the chart indicate conjunctions between planets or stars and planets.  For Mercury, the yellow triangles with the letters “GE” indicate the planet’s greatest separation from the sun as we see it; this is known as greatest elongation.  For Venus, the yellow diamond with the letters “GB” indicate when the planet is at its brightest.

Four planets are visible in the morning sky early in the year.  Mercury makes one of its two best appearances in January.  The second occurs at the end of the year.  Mars moves past Jupiter and Saturn early in the year.  Mercury makes two more morning appearances during twilight:  April and August.  Venus jumps back into the morning sky late in the year.  Jupiter also re-enters the sky later in the year.

Here are some highlights from planetary events in the morning sky  (Click the images to see the details):

 

The morning sky has a sky full of planets leading up to oppositions from Jupiter, Saturn, and Mars.

2018: Venus the Evening Star

Photograph of Venus and the moon during twilight on September 3, 2016 -- the most recent evening apparition of Venus.

Figure 1: Venus appears in the evening sky during its 2016 evening appearance.

This article has many details about the appearance of Venus in the evening sky during 2018.  Bookmark it so that you can return to check the details.  Stop back, we’ll update this page with photos throughout the article and display a collection of them at the end.

Venus shines brightly as an Evening Star for most of 2018. It appears in the western sky as the three bright outer planets dance in their retrograde loops throughout spring and summer. 

These articles outline the planetary activity during 2018:

Unless noted, the charts in this article are computed for Chicago, Illinois, in the U.S.A. Central Time Zone (CST, -6 hours).  Daylight Saving Time (CDT, -5 hours) is shown when that occurs.

Figure 2: The chart shows the setting time of Venus compared to sunset, along with the setting time differences of other bright planets, stars and the moon (circles).  The boxes indicate conjunctions with other stars and planets.  The yellow triangle with the letters “GE” indicates Venus’ greatest elongation.  The greatest brightness is marked with the yellow diamond and the letters “GB.”

Introduction

The setting chart above shows the setting of Venus and other planets, bright stars, and the moon (circles) compared to sunset.  The white boxes indicate Venus conjunctions with other planets and stars.  After its solar superior conjunction in early January, Venus slowly moves into the evening sky.  Two months pass before it sets an hour after sunset, shining brightly in the western sky after sunset.  With the lengthening twilight that occurs at mid-northern latitudes (the chart is graphed from data for Chicago, Illinois), Venus reaches its latest setting time after sunset (2 hours, 40 minutes) in late May.  It appears low in the western sky after the end of twilight from March 28 through July 24 (for this latitude).  Meanwhile it passes through the stars of Taurus with a conjunction with Aldebaran, then Pollux, and finally Regulus during the evenings when it sets after twilight.  Because of the low inclination of the ecliptic it reaches greatest elongation and its duration of greatest brightness when it sets during evening twilight.  This article provides more detail about these events during the early evening hours of 2018.

Superior Conjunction Starts the Evening Apparition

Figure 3: The evening appearance of Venus begins when the planet passes superior conjunction when Venus is on the far side of the sun. At this time it is in the sky during the day and in the south at noon. The noon line on the chart points through Venus, indicating its direction and time.

The Venus apparition begins on January 9, 2018 (1:02 a.m. CST) when it passes superior conjunction. We cannot see Venus as it is on the far side of the sun and is in the sky with the sun. It rises in the east at sunrise, is in the south at noon, and sets in the west at sunset.

After its solar conjunction, Venus climbs slowly in the western evening sky. A month after conjunction it sets about 35 minutes after sunset, setting about 10 minutes later each week.

The chart above (Figure 2) shows the setting times of Venus, other bright stars, and planets compared to Sunset. Moon set is shown by the circles. We should note that these are setting times when Venus and the other celestial objects cross the natural horizon, leaving the sky.  Look for them between sunset and their setting time intervals. By mid-February, Venus appears low in the Southwest after sunset.

While it is the brightest “star” in our sky, it continues to grow in brightness as it slowly catches our planet.  For Venus, Earth is an outer planet, like Mars is for Earth.  Moving on a shorter orbit and at a faster speed — Venus revolves around the sun every 225 days, yet successive solar conjunctions (inferior-inferior or superior-superior) occur every 584 days. These configurations are named from Venus’ position compared to Earth.

Mercury Conjunction, March 18

Figure 4: The first conjunction of this appearance of Venus is with Mercury on March 18, 2018 during evening twilight.

By March 1 Venus continues to set later, now about 100 minutes after sunset. It still sets before the end of twilight . On March 18, Mercury passes about 4° from Venus with the moon nearby. By the end of March (March 28), Venus now sets after twilight ends.  It rapidly moves eastward compared to the background stars.

Venus in Taurus

Figure 5: During late April , Venus moves among the stars of Taurus. On April 24, Venus moves past the Pleiades star cluster. They are about 3.5 degrees apart. Look at the region with binoculars to see the region’s star clusters.

By late April, Venus moves through the stellar background of Taurus with its two bright star clusters:  Pleiades and Hyades.  The Pleiades is a compact grouping of bright bluish stars known to school children as “The Seven Sisters.”  The cluster resembles a tiny dipper.  To the unaided eye, 6 or 7 stars are visible.  A dozen or so through binoculars.  A few hundred through telescopes.  The Hyades are nearby.  This group resembles a check mark, a letter “V” when Aldebaran is included, although it is not part of the cluster.

Astronomical theory describes that stars are formed in bunches from a stellar, gaseous nebula.  Over time the mutual gravitation pull of the stars within the cluster is not strong enough to keep the group together.  The Hyades and Pleaides are close enough (within 400 light years) that they can be seen without a telescope.  Many star clusters are just beyond the perception of our eyes.  Binoculars help reveal them.  If you’re interest in star clusters is piqued, start here.

Figure 6: Venus passes 6.5 degrees from Aldebaran on May 2. With binoculars look at this region every clear night while Venus is there.

During the next week, Venus moves between the Hyades and the Pleiades, passing 6.5 degrees from Aldebaran on May 2.  Venus and the surrounding stars are less than 15 degrees above the west-northwest horizon.  Look at this region with binoculars every clear night.

Figure 7: Venus moves between the horns of Taurus (Zeta Tauri and Elnath during mid-May. It passes within 4 degrees of Elnath on May 13 and about 3.5 degrees from Zeta Tauri the next evening.

Venus and Moon

The moon passes Venus during its monthly succession of phases.  On the setting chart (Figure 2) above, note that the moon and Venus set at nearly the same time on several days.  We chose three of those dates to feature here.  In the charts in this section (Figure 7, Figure 8, and Figure 9)  the moon appears near Venus.  Here are some of the details:

  • May 17, 2018:  Venus and the moon are 6.2 degrees apart at chart time (9:15 p.m. CDT).  They are 14 degrees above the west-northwest horizon.  The moon is only 2.5 days old.  This region of the sky is full of bright stars; Capella is shown on this chart.  To keep the scale of the three charts the same, the view is limited.
  • July 15, 2018:  The nearly 3-day-old moon is slightly less than 2 degrees from Venus.  (The moon is over sized on this charts.)  The star Regulus is 6.75 degrees to the lower right of Venus.  (There is a conjunction with Regulus on July 9.  See the text for more details.)
  • August 13, 2018:  The moon is 2.5 days old and appears 10 degrees to the right of Venus.

Venus & Pollux

Figure 11: Venus passes the Gemini Twin Pollux on June 7.

After its conjunction with Aldebaran, Venus continues its eastward movement against the stars as it moves into Gemini, reaching Pollux in Gemini in early June.  It passes 4.75 degrees from Pollux on June 7.  The trio of stars is about 15 degrees above the west-northwest horizon.

Venus and the Beehive

Figure 12: Venus passes the Beehive star cluster on June 19. It is dimmer than the star clusters in Taurus.

After Venus moves through Gemini, it moves into a region with inconspicuous stars known as Cancer.  The Beehive star cluster is in this star field.

Observers with sharp eyesight and a darker sky can see the cluster without binoculars.  For them it appears as a cloudy patch nearly halfway from Pollux to Regulus.

With binoculars stars are visible in the cluster.

The cluster is farther away (500 light years) and consequently dimmer than the Hyades or Pleiades.  Point your binoculars at Venus at 9:30 p.m. CDT, the Beehive cluster is immediately to the left of the brilliant planet.

Venus Meets Regulus

Figure 13: Venus passes within 1 degree of Regulus on the evening of July 9.

Venus continues moving eastward along the ecliptic through the stars of Cancer toward Leo.  In early July, Venus passes the next signpost of the ecliptic, Regulus.  This vivid blue star is less than one degree from Venus on July 9.  On the chart above (Figure 13), the pair is 12 degrees above the western horizon at chart time.

See Five Planets

During late July, observers at more southerly latitudes can see five planets at once.  This will be difficult for observers at mid-northern latitudes.  See the details in this article.

During the time when the five planets are visible, Venus starts setting before the end of twilight on July 24 (at Chicago’s latitude).

Greatest Elongation — East of the Sun

Figure 14: Venus reaches its greatest angular separation from the sun on August 17 when it is 46 degrees from the sun.

Venus is now rapidly catching our planet and growing in brightness.  It continues to move eastward from Regulus and the stars of Leo toward Spica.  On August 17, Venus appears farthest from the sun, known as the greatest elongation (angle).  Venus is about half the distance it was at the Mercury conjunction (March 18) and over 50% brighter.  Venus is now setting about 100 minutes after sunset and its setting time compared to the sun is decreasing about 5 minutes sooner each week.  This is displayed with the yellow triangle and the letters “GE” on the setting chart (Figure 2).  The result is that Venus is lower in the sky each night at the same time interval after sunset.

Venus is now 70 days before inferior conjunction.  It continues to catch Earth and brighten in the sky.

Venus Passes Spica

Figure 15: Venus passes 1.25 degrees from Spica on August 31. Venus appears lower in the sky as it heads toward inferior conjunction.

Two weeks after the greatest elongation, Venus passes 1.25 degrees from Spica. After the conjunction, Venus and Spica continue to set at about the same time — growing in separation — until they disappear into the sun’s glare in October.  Venus sets farther left (south) along the horizon.

Greatest Brightness

Figure 16: Venus reaches its greatest brightness on September 21st.

About September 16 and for the next two weeks, Venus enters its phase of greatest brightness.  The midpoint is September 21st.  This date is displayed with a yellow diamond and labelled “GB” on the setting chart (Figure 2).

Jupiter, But no Conjunction

Figure 17: On September 28, Jupiter closes with 14 degrees of Venus. There is no conjunction during this Venus apparition.

After its opposition, Jupiter appears farther west each night.  During late summer Jupiter sets 80 minutes after sunset and it appears that Venus and Jupiter are headed toward a conjunction.  After the Spica conjunction, Venus rapidly dives toward the sun’s glare as it moves toward its inferior conjunction with the sun.  The closest Jupiter gets is 14 degrees on September 28, setting about 70 minutes after Venus.  See the setting chart (Figure 2) to note the similar setting times of Venus and Spica and the minimum separation of Venus and Jupiter.

Inferior Conjunction Ends the Apparition

Figure 18: Venus overtakes and passes Earth on October 26, moving between our planet and the sun.

During October, Venus rapidly disappears into the sun’s glare and moves between Earth and the sun (inferior conjunction) on October 26 (9:16 a.m. CDT). This completes the evening apparition for Venus during 2018.

After its solar conjunction, Venus quickly moves into the morning sky. By Nov 8 it already rises at the beginning of twilight, gleaming in the eastern morning sky.

Summary

During 2018, Venus appears in the western evening sky.  It passes Mercury, Aldebaran, Pollux, Regulus, and Spica.  While its latest setting time is 160 minutes after sunset, its sets mostly during evening twilight during this appearance.  Late in the apparition, what looks like, an impending Jupiter conjunction never occurs.  There are several opportunities to view Venus and the moon.  Here we highlighted the close passings on May 17, July 15 and August 13.  Venus also passes the star clusters Pleiades, Hyades, and Beehive.  Binoculars help spot the clusters with brilliant Venus nearby.  Happy observing!

With the Moon

The moon is close to Venus on these dates (One degree is the size two full moons appear to our eyes without a telescope:

  • February 16 – 2.5 degrees (d)
  • March 18 – 4d
  • April 17 – 5.5d
  • May 17 – 6.2d
  • June 15 (7.5d) & 16 – 7.3d
  • July 15 – 2.2
  • August 13 – 10.5d
  • September 12 – 9d
  • October 11 – 3.1d

Photos

2017, November 14: Venus and Jupiter #astronomy

Venus appears 1.4 degrees to the lower left of Jupiter this morning, one day after their epic (close) conjunction. Venus is moving toward its superior conjunction (January 9, 2018) and into the evening sky. Jupiter is heading toward its opposition (May 8, 2018).

The wider scene shows the planetary pair low, just above the trees and housetops.  The waning crescent moon over 30 degrees to the upper right of Venus.

For more information about sky watching events:

2018: Five Planets Visible at Once

During 2018, the five naked eye planets — those visible without a telescope (Mercury, Venus, Mars, Jupiter, and  Saturn) — can be seen during the early evening in late July.  It should be noted that the farther south the observer, the easier they are to see as illustrated in the following diagrams.  From more northern latitudes, such as mine in Chicago (and farther north), Mercury sets or is very close to the horizon when Mars becomes visible in the east.

The summer sky is full of planetary activity.  Venus shines brightly in the western sky.  Jupiter, Saturn, and Mars are passing through their oppositions and displaying their retrograde patterns.  During late July, Mercury pops into the evening sky for a short visit.

These articles outline the planetary activity during 2018:

From Latitude 33 degrees North (Dallas, Texas)

From latitude 33 degrees North, the planets span across the sky from the east-southeast to the west-northwest.

Look for the five planets two to three days before and after the charted date (July 21).  Find a clear horizon to see Mercury; binoculars may be needed to initially identify it.  Twilight is longer, so look for the planets around chart time and before Mercury disappears below the horizon.  The moon appears near Jupiter.  Saturn is low the south-southeast, above the stars of the Teapot (Sagittarius).

Latitude 33 degrees South (Sydney, Australia)

(For my southern hemisphere readers)

From the southern hemisphere where the sun and planets appear in the north, the five naked eye planets are easily visible at 6:30 p.m. AEST.  Tonight the moon is closer to Jupiter than viewed hours later in North America. Twilight is shorter at this season in the southern hemisphere.  The line-up is the same across the sky as from the northern latitudes.  Mercury in the west-northwest arching back to Mars in the east-southeast.

The farther south, the better the view.

For those at favorable latitudes, look for the planets in late July.  Let us know what you see!

2017, November 13: Venus-Jupiter Conjunction! #astronomy

 

Venus passes Jupiter this morning.  The pair is only only 1/3 degree apart!

The key to locating them is to find them when they are high enough in the southeast sky, yet the sky is dark enough.  Tomorrow, Jupiter is above Venus, about 1 degree apart.

For more information about sky watching events: