2016: Late September Morning Sky


During September a congregation of bright stars shines from the southeastern sky during predawn hours.  Sirius, the Dog Star, is the brightest star among these.  It is the brightest star in the night sky, although Venus, Jupiter and Mars shine brighter than Sirius.  Procyon appears to the upper left of Sirius and the bright stars of Orion (Betelgeuse and Rigel) shine above Sirius.

Currently there are no bright planets in the morning sky.  Mercury (see article) and Jupiter (see article) appear in the morning  sky during the next several days.  Venus, Mars and Saturn are currently in the evening sky.


Nearly a year ago, Venus appeared in the morning sky.  It was close enough to Sirius that both fit into a camera frame.  That bright star in the morning sky in the southeast is Sirius.

Our images and charts collections are available here –> http://goo.gl/Sfp1ur

See our article about Venus’ evening appearance.

See our  article outlining the planets in the evening sky in 2016.

2016: Sidereal Signs of Autumn


The autumnal equinox occurs on September 22, 2016 at 9:21 a.m. CDT.  At this moment the sun’s rays are most direct at the equator.  Astronomically, the sun’s coordinates are at 12 hours of right ascension and 0 degrees of declination.  If you not into the technicalities of this event, there’s another way to note that autumn has arrived.  One way is to look toward the western horizon early in the evening.  Near the time of the start of autumn, the Big Dipper lies low in the northwest.  Perhaps trees or your neighbor’s house blocks its view.  Locate a clear horizon to see these stars.

 In North America, the Big Dipper is one of the first star patterns that children learn when they visit their local planetarium.  Its familiar seven stars are part of the formal group call Ursa Major, the Great Bear.  The handle of the dipper points toward Arcturus, a distinctly red-orange star in the western sky.  Follow the bend of the Big Dipper’s handle toward the star Arcturus, or as the familiar saying goes, “Follow the arc to Arcturus.”  Arcturus is part of a large constellation known as Bootes, the Herdsman, that resembles a kite.

As a large celestial calendar, the stars indicate the seasons as well as the sun’s location on the great sidereal sphere.  As the earth revolves around the sun, we see a distinct layout of stars in the night sky each season.  The Big Dipper and Arcturus in the western sky make a sidereal sign that autumn has arrived.

2016, October 3: Venus and the Moon


Venus and the moon appear close together on the evening of October 3, 2016. They are separated by about 2.25 degrees.  Venus is making its appearance in the western evening sky.

Venus is nearly 3 degrees from the star Zubenelgenubi.  On ancient star maps this star and its neighbor, Zubeneschamli, were part of Scorpius.  Their names are translated as the Northern Claw and Southern Claw (of the Scorpion).  Today they are part of Libra, the only inanimate object that forms the background for the motion of the sun, moon, and planets.

Our images and charts collections are available here –> http://goo.gl/Sfp1ur

See our article about Venus’ evening appearance.

See our  article outlining the planets in the evening sky in 2016.

2017: The Mars-Venus Encounter


A Recent Venus-Mars Conjunction

On an interval that varies from several days to nearly 23 months, Venus and Mars can appear very close together in the sky.  These conjunctions can be very close (Epoch) or with very wide separations.  During the conjunction displayed in the above image (November 3, 2015), the planets appeared about 0.7 degree (42 minutes) apart.  On October 5, 2017, they appear over 3 times closer with a separation of .22 degree (13.2 minutes).  (In the sky we measure the separation of objects by a geometric angle as seen from Earth.  The full moon’s diameter is about 0.5 degree. Your little finger at arm’s length covers a full moon.  Try it during the next time the moon is full. In the above image Venus and Jupiter are separated by about 7 degrees.  Your fist at arm’s length covers about 10 degrees in the sky.)


At its brightest, Mars shines as the third brightest starlike object in the sky, following Venus and Jupiter.  This occurs when Mars is at opposition, when it is closest to Earth and opposite the sun in the sky.  At opposition, Mars rises in the east at sunset, appears in the south at midnight and sets in the west at sunrise.  Conjunctions of Mars (and the planets beyond Earth) with Venus occur when Venus is within 47 degrees of the sun.  This angle is the greatest angular separation that Venus has from the sun from our home planet view.  Yet, if Venus and Mars appear too close to the sun, they are lost in the sun’s brightness and not visible from Earth.  Because Mars is far from our planet during a Venus conjunction, it is not near its maximum brightness, so Venus always appears very bright in the sky and a conjunction with Mars occurs when the Red Planet is dimmer. A Venus-Mars conjunction does not occur when Mars is near its brightest (at opposition)  Notice Mars’ brightness in the image at the beginning of this article from the 2015 conjunction.

Notice that Venus does not appear at opposition; so it is not visible at midnight.


At the time of this writing, Venus has recently entered the evening sky and passed its Epoch Conjunction with Jupiter.  On September 15,2016, Venus appears low in the sky in the west.  Saturn and the star Antares are farther south.  Mars is beyond them, about 62 degrees from Venus.


From a view outside the solar system, this 62-degree angle is represented in the chart above.  In all these charts, Earth is at the geometric vertex of the angle.


As the dates advance toward the New Year, Venus moves closer to Mars.  The chart above shows the setting times of planets, the moon, and selected stars compared to sunset during part of 2017, until Mars disappears into the sun’s glare.  On January 1, 2017, notice on the chart that The moon sets close to the time of the setting of Venus (14 minutes difference).  This indicates that they appear close to each other in the sky.  Mars follows Venus by about an hour.


This chart represents what we see in the sky during the early evening on New Years Day.  Venus and the Moon are 4 degrees apart with Mars about 12 degrees to the upper left of Venus.

During January 2017, Venus and Mars appear to move closer together as the setting lines of the two planets begin to converge.


On February 3, 2017, the planets close to 5.5 degrees, with Mars setting 19 minutes after Venus.  The chart above shows their close angular proximity, but they are nearly 126 million miles apart in space, over 300 times the distance between the earth and the moon.


In the sky, brilliant Venus dominates the southwestern sky with dimmer Mars 5.5 degrees to its upper left.

After this near meeting, Venus rapidly moves back toward the sun, as indicated by the rapidly decreasing time it sets after the sun as indicated by the setting graph earlier in this article.  The planets appear farther apart on the sky as the time difference in their settings increases.


On March 1, the planets are 13 degrees apart with the moon 5 degrees to the lower left of Mars.

By March 15, Venus sets at the beginning of twilight and 4 days later it sets in bright twilight.  This is a rapid plunge into the sun’s glare.

On March 25, Venus passes between the earth and sun (inferior conjunction) and rapidly moves into the morning sky.  Mars slowly sets earlier each night until it disappears into the sun’s glare toward its solar conjunction on July 27.


In late April, Mars moves through Taurus, which has two prominent star clusters:  Pleiades and Hyades.  The Pleiades star cluster is a compact cluster of many blue stars.  Commonly named the “Seven Sisters,” the cluster is a spectacular sight through binoculars.  Mars passes closest to the cluster (3.5 degrees) on April 21.    With binoculars the cluster and the planet are be visible at the same time.

The bright star Aldebaran appears in line with the Hyades cluster; its loosely collected stars resemble a check mark.  The Hyades cluster is another spectacular view through binoculars.


On April 28, the moon joins the view in the western sky when it is 4 degrees to the upper left of Aldebaran.  Mars continues its planetary motion among  these stars.


On April 29, Mars and Aldebaran set at the same time, but they are nearly 7.5 degrees apart.  By this date, Venus is shining brightly in the morning sky rising about 90 minutes before sunrise.


On May 6, Mars passes 6.5 degrees to the upper right of Aldebaran.  A few days later, Mars begins setting during evening twilight, each night setting deeper into the glow after sunset;  It moves behind the sun on July 27.

Upcoming Venus-Mars Conjunctions

  • October 5, 2017 — 13.2 minutes separation
  • August 24, 2019 — 18.6 minutes
  • July 3, 2021 — 29.4 minutes


Our images and charts collections are available here –> http://goo.gl/Sfp1ur

See our article about Venus’ evening appearance.

See our  article outlining the planets in the evening sky in 2016.

2016, September 3, Moon and Venus


The waxing crescent moon and Venus shine from the western sky this evening as seen from the Chicago area.  The moon is nearly 2.75 days past its new phase and nearly 6 degrees to the upper left of Venus.  Venus is beginning its appearance in the evening sky after its Epoch (close) Conjunction with Jupiter.

Later in the week, the moon passes Saturn and Mars

Our images and charts collections are available here –> http://goo.gl/Sfp1ur

See our article about Venus’ evening appearance.

See our  article outlining the planets in the evening sky in 2016.

2016, September 2: Venus, Jupiter, Moon, Mars & Saturn


Brilliant Venus gleams during twilight this evening as seen from the Chicago area with a waxing crescent moon and Jupiter appearing lower in twilight.  (To see Jupiter click the image to see it larger.  The planet appears at the tip of the  arrow.)  The moon is 5 degrees to the lower right of Venus with Jupiter another half degree farther to the  right.  Notice the separation of Jupiter tonight compared it its position during the Epoch (close) Conjunction last Saturday.

Here’s a preview of the Moon and Venus tomorrow evening.

Our images and charts collections are available here –> http://goo.gl/Sfp1ur

See our article about Venus’ evening appearance.

See our  article outlining the planets in the evening sky in 2016.


Meanwhile, Mars, Saturn and the star Antares appear in the south as the sky darkens.  The trio is in the sky during the evening, setting in the west as they appear to move that direction during evening hours.  Mars is advancing farther east compared to the starry background.  Tonight it is 6 degrees from Saturn and 5 degrees from Antares.

2016: September, Mars, Saturn and the Moon


During early September 2016, the moon passes Saturn, Mars, and the star Aldebaran in the evening sky.  The charts are shown for the Chicago area about 80 minutes after sunset.  Mars is rapidly moving eastward against the starry background.  Notice its location during August.  Here are the events of September 7-9,2016:

  • September 7.  The moon  is 11 degrees to the east of Saturn.  Antares is 6 degrees to the lower left of Saturn.  Mars is 10 degrees to the left of Saturn.
  • September 8.  The first quarter moon is 4 degrees above Saturn.
  • September 9, The waxing gibbous moon is 8 degrees above Mars.

Our images and charts collections are available here –> http://goo.gl/Sfp1ur

See our article about Venus’ evening appearance.

The  article outlining the planets in the evening sky in 2016