Venus and Mars, September 3, 2015


Venus is rapidly moving into the morning sky.  (This observer first saw Venus on the morning of August 27.)  On the morning of September 3, Venus appears about 9 degrees to the lower right of Mars.  Venus appears about 300 times brighter than the Red Planet.

For more information about:

A Sky Full of Planets in the Morning Sky in 2015

Venus as a Morning Star, 2015-2016

September 2015 Sun and Moon


The length of daylight decreases rapidly during September.  At the beginning of the month, the sun is in the sky for over 13 hours.  By month’s end, the sun is above the horizon for about 11 hours, 45 minutes.  On the chart above, the sun’s yearly daylight hours is displayed in the red graph.  The blue-shaded graph shows the daylight hours during September.

The sun reaches the autumnal equinox on September 23, 2015, at 3:22 a.m. CDT.  At this time the sun’s rays shine directly on the equator.  The sun passes directly overhead at noon as seen from the equator.  Until next March, the sun’s intensity is directed toward the southern hemisphere, where the seasons are opposite of those in the northern hemisphere:  A cold and frosty day during December in Chicago is a warm, summer December day in Sydney.


NASA Photo

NASA Photo

Phase Date/Time Moonrise Moonset
Last Quarter 09/05/15 (4:54 a.m.) 11:26 p.m. (09/04) 1:06 p.m.
New Moon 09/13 (1:41 a.m.) 6:47 a.m. 7:16 p.m.
First Quarter 09/21/15 (3:59 a.m.) 2:13 p.m. 12:18 a.m. (09/22)
Full Moon

Lunar Eclipse

09/27/15 (9:50 p.m.) 6:32 p.m. 7:15 a.m. (09/28)
Times are Central Daylight Time for Chicago, Illinois, from US Naval Observatory calculations. (For mjb)

A spectacular lunar eclipse occurs on the evening of September 27 that is visible across North America.   More details in an upcoming posting.

A Sky Full of Planets in the Morning Sky, 2015


A recent appearance of Mars and Venus

Venus, Jupiter, Mars and Mercury appear together in the morning sky during the second half of 2015.  Brilliant Venus moves from the evening sky to the morning sky.  After the Great Epoch Conjunction with Jupiter in the summer of 2015, the planets pass again in the morning sky, yet not as close as the June conjunction.


The chart above (from US Naval Observatory data) shows the rising times of Venus, Jupiter, Mars and Mercury compared to sunrise from June 14, 2015 through November 8, 2015.

Mars passed behind the sun (superior conjunction) on June 14 and slowly climbs into the morning sky.  Its rate is much slower than the other three planets visible in the 2015 morning sky.  While Mars is near our planet, it appears to move through its orbit at about half our speed, so it takes longer periods to move through the sky.  This is indicated by the slope of the Mars rising line compared to the other planets.  Other conjunction dates:

  • Venus, August 15, 2015 (inferior conjunction.
  • Jupiter, August 26, 2015 (conjunction)
  • Mercury, September 30, 2015 (inferior conjunction)

The chart above shows the rising times of the planets compared to the sun.  When the rising lines of the planets cross, they rise at the same time indicating they are close together in the sky.  The conjunctions (closest approach as seen from the Chicago, Illinois area) occur within a day or two of these dates.  The important dates of the planet groupings:

A:  Venus and Mars, September 3, 2015
B:  Mercury at Greatest Elongation, October 16, 2015, appearing with the trio in morning sky.
C:  Jupiter and Mars, October 18, 2015
D:  Venus and Jupiter, October 25, 2015
E:  Venus and  Mars, November 3, 2015

A.  Venus and Mars, September 3, 2015


This is a widely spaced grouping shown above at 5:30 a.m. CDT.  Venus and Mars are nearly 9 degrees apart.  Venus is nearly 300 times brighter than Mars.  (Click the images to see them larger.)


A week later, the crescent moon joins Venus and Mars, appearing about 4 degrees from Venus.


During the next month, Venus moves higher in the sky and Jupiter joins the Venus and Mars.  The crescent moon moves through the region on October 8 and October 9.  On the first date the moon is 4 degrees from Venus and 5.5 degrees from Jupiter on the next morning.

 Mercury at Greatest Elongation, October 16, 2015


Mercury appears at its greatest (elongation) separation from the sun and appears far below the planetary waltz that appears higher in the sky.

C:  Jupiter and Mars, October 18, 2015


Jupiter and Mars are less than a half degree apart. Jupiter is 25 times brighter than Mars.

D:  Venus and Jupiter, October 25, 2015


While not an Epoch Conjunction, Venus and Jupiter are just over 1 degree apart (not an Epoch Conjunction) with Mars to their lower left.  The next Venus-Jupiter conjunction is August 27, 2016, when the planets are less than 1 degree apart, only slightly closer than this conjunction.

E:  Venus and  Mars, November 3, 2015


In this second pairing, Mars and Venus are very close, about 3/4 degree apart.  Venus still overwhelms Mars in brightness.

The next few months promise a sky full of planets.  Take a look.

Venus as a Morning Star, 2015-2016


A recent appearance (2012) of Venus with other planets in the morning sky.

Venus appears in the morning sky after its spectacular Epoch Conjunction with Jupiter in the summer evening sky in 2015.  As a Morning Star, Venus appears with three other planets during mid-October 2015.  This article describes the appearance of Venus and highlights its appearance with the planets, bright stars and the moon.  Bookmark this page and return here for photographic updates as well as revisit the main blog page for images of the planets and the moon.


Venus revolves around the sun closer to the sun than our planet.  Venus completes  a solar orbit in nearly 225 days.  Since our planet moves during this period, Venus catches our planet and moves between it and the sun (inferior conjunction) every 584 days.  Because of the sun’s brilliance, Venus is invisible during this time, unless it is precisely aligned with Earth and the sun so that from our view, Venus appears to move across the  face of the sun as it did in 2012.  The image below shows the most recent transit.


While Venus passes through inferior conjunction frequently, the next time it appears to cross directly in front of the sun is 2117.


After inferior conjunction Venus vaults into the morning sky.  Within 2 weeks of inferior conjunction, Venus rises 80 minutes before the sun.  Within a month it rises nearly 3 hours before the sun!  This bright planet easily outshines all the other stars and planets in the sky and it’s brilliance in unmistakable.  (The chart of above is made from sunrise data and Venus rise data for Chicago, Illinois, provided by the US Naval Observatory.  The chart shows Venus’ rising time compared to the sun. )


As Venus moves into the morning sky it grows in brightness until September 21, when it reaches it maximum intensity.  At this time it appears over 20 times brighter than Sirius, the brightest star in the night sky.  The chart above shows the relative positions of Earth, Venus and sun at Venus’ greatest brightness.  The green symbol on the previous Venus rising chart indicates when the sun rises on this date.


In another month (October 26), Venus reaches it greatest separation (greatest elongation) from the sun, rising nearly 4 hours before the sun.  The yellow symbol on the Venus rising chart above shows Venus’ rising time.

As if disappearing around the curve of a race track, Venus begins a long, slow trip to the far side of the sun from our view.  Its brightness fades slightly, but still remains the brightest object that looks like a star.   As the new year (2016) opens, Venus still rises nearly 3 hours before the sun.  By late March, it rises about 30 minutes before the sun and in bright twilight as it does a slow fade into the sun’s brightness.


Venus disappears into the sun’s glare and reaches superior conjunction on June 6, 2016.


The chart above shows the rising points of Venus and the sun along the eastern horizon.  As Venus moves from inferior conjunction is rises south of the sun along the horizon. Beginning August 31, Venus rises north (left) of the sun along the horizon.  Venus’ rising point remains north of the sun until January 14, 2016 when it again rises south (right) of the sun on the eastern horizon.  It remains south of the sun’s rising point until superior conjunction.  Notice that the sun’s rising point changes daily from the tilt of our planet.  It rises within 15 angular degrees of southeast at the winter solstice.  (The Venus and the sun rising points provided in data from the US Naval Observatory.)

As Venus appears in the morning sky, it appears with planets, bright stars, and the moon.  Interesting appearances are noted below.

Stars and Planets

  • Mars, 09/03/15
  • Regulus, 10/09/15
  • Mercury, 10/16/15 — widely separated (28 degrees)
  • Jupiter, 10/25/15
  • Mars, 11/03/15 (Yes, Mars has two appearances with Venus)
  • Spica, 11/30/15
  • Zubenelgenubi, 12/18/15
  • Antares, 01/08/16
  • Mercury, 04/06 (difficult) — Venus is within 6 degrees of the sun and rises only 16 minutes before the sun.)


  • September 10, 2015 (3.2 degrees separation)
  • October 8, 2015 (4 d)
  • November 7, 2015 (1.5 d)
  • December 7, 2015 (2.5 d)
  • January 6, 2016 (6 d), January 7, 2016 (6.4 d)
  • February 6, 2016 (4.7 d)
  • March 7, 2016 (3.1 d)

August 2015 Sky Watching



The days of August lose about 75 minutes of daylight, finishing with about 13 hours, 10 minutes of sunshine.  The red line on the chart above shows the length of daylight for each day during the year.  The shaded area shows the daylight for this month.


NASA Photo

NASA Photo

Phase Date/Time Moonrise Moonset
Last Quarter 08/06/15 (9:03 p.m.) Midnight 1:06 p.m.
New Moon 08/14/15 (9:53 p.m.) 6:02 a.m. 7:44 p.m.
First Quarter 08/22/15 (2:31 p.m.) 1:37 p.m. 11:57 p.m.
Full Moon 08/29/15 (1:35 p.m.) 7:25 p.m. 7:13 a.m.
Times are Central Daylight Time for Chicago, Illinois, from US Naval Observatory calculations. (For mjb)

Perseid Meteor Shower

A Perseid meteor streaks across the sky during the Perseid meteor shower on Tuesday, Aug. 11, 2009 in Vinton, Calif. (AP Photo/Kevin Clifford)

A Perseid meteor streaks across the sky during the Perseid meteor shower on Tuesday, Aug. 11, 2009 in Vinton, Calif. (AP Photo/Kevin Clifford)

August brings the annual Perseid meteor shower.  The meteors originate from Comet Swift Tuttle (109P).  Comets are composed of ices and dust.  Comets move from the solar system’s colder zones and swing around the sun in elongated orbits.  During the time they are near the sun, the ices evaporate and the dust is scattered in wide swaths along the comet’s pathway. For the Perseids, the cometary dust cross our planet’s orbital zone.  During mid-August each year, our planet crosses that debris and the small dust grains enter the atmosphere, vaporize, and cause the air around them to glow — a shooting star or meteor.  The meteors seem to originate from the constellation Perseus, indicating the name of the shower.  The Perseids join 10 other annual showers that are from cometary debris.

Perseus rises in the northeastern sky at sunset.  During the night it rises higher in the sky, reaching its highest point just after sunrise.  Perseids can be seen anywhere in the sky, but they seem to emanate from Perseus.  Sporadic meteors also appear at the time of the shower, but their flight is from random directions.

At its best during the early morning of August 13, as many as 90 meteors each hour can be seen.   With the moon nearly new, the sky is free from distracting moonshine.  The predicted visible rate is diminished by street lights other outdoor lights.  The visible rate is further reduced by the reality that a single person cannot observe the entire sky all the time.  For any single person, the rate is likely 15-20 meteors per hour.  Perseids are best observed with four people, each looking in different directions in a very dark location.



During early evening hours, Saturn appears in the southern sky near the star Antares.  The moon appears near Saturn on the evening of August 22.



Mars enters the morning sky, appearing low in the northeastern sky.  The moon helps with its identification on the morning of August 12, when it is 9.5 degrees to the upper right of the planet.  The stars Castor and Pollux appear above Mars.



Always difficult to see, Mercury briefly appears in the western evening sky during mid-month.  The moon appears 5 degrees to the left of Mercury on August 16.  Use binoculars to locate the moon.  Move the binocular so that the moon appears on the left side of the visible field of view, Mercury should appear on the right side of the view.  Then try to locate each without optical help.

Sun and Moon, July 2015


The sun’s height in the sky is now past its highest point for this solar orbit.  For the next several months, it appears lower in the sky each day at noon.  As the noontime height lowers, the length of daylight decreases at the mid-northern latitudes.  At the latitude of Chicago (42 degrees N), the length of daylight decrease by nearly 45 minutes during July.  At month’s end the length of the day is about  14.5 hours.

On July 6, our planet reaches the farthest point in its revolution from the sun.



NASA Photo

NASA Photo


Phase Date/Time Moonrise Moonset
Full Moon 07/01/15 (9:20 p.m.)07/31/15 (11:04 p.m.) 7:59 p.m.7:27 p.m. (07/30) 6:06 a.m. (07/02)6:00 a.m. (07/31)
Last Quarter 07/08/15 (3:24 p.m.) 12:06 a.m. 12:59 p.m.
New Moon 07/15/15 (8:24 p.m.) 5:17 a.m. 7:54 p.m.
First Quarter 07/24/15 (11:04 p.m.) 1:53 p.m. 12:43 a.m. (07/25)
Times are Central Daylight Time for Chicago, Illinois,
from US Naval Observatory calculations. (For mjb)

Notice the table above shows two full moons in this month, the so-called “Blue Moon” effect.  The moon does not turn blue in this meaning; rather it refers to the infrequency of an event.  The name has other meanings as well.  A similar effect occurs during January 2018.  These moons must occur during months with 31 days.  Additionally, it is possible for February not to have a full moon because a month of phases takes 29.5 days.


On the evening of July 18, the crescent moon appears about 1 degree below Venus and nearly 7 degrees from Jupiter.  The two planets are nearly 6 degrees apart.


On the evenings of July 25 and July 25, the moon appears near Saturn.  On the chart above (July 26), the moon is about 9 degrees to the left of Saturn.  On the previous night, the moon is 4 degrees to the right of Saturn.

Venus and Jupiter, June 30, 2015


Brilliant Venus and bright Jupiter are at their closest this evening as seen from the Chicago area.  They appear less than an apparent moon diameter apart.


Venus is over 11 times brighter than Jupiter.


For more about the conjunction, see this summary article.

See this article for more as Venus as an Evening Star.


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