2017, June: Saturn at Opposition

The Ringed Wonder reaches opposition on the morning of June 15.  At this time our planet is between Saturn and the sun.  On the evenings around opposition, Saturn rises in the opposite direction from the sunset point.  As Earth rotates, it rises higher in the sky each hour.  At midnight it is in the southern sky.  From that time, the planet begins to appear lower in the sky, setting in the southwest as the sun rises in the northeastern sky.

On the evening of June 8, the waning gibbous (just past full) moon appears nearly 3 degrees to the upper left of Saturn.  The reddish star Antares is nearly 16 degrees to the upper right of Saturn.

This is the last opposition of naked eye planets this year.

The three outer planets, which includes Pluto, have oppositions this year, but they are only observed with optical assistance:

  • Pluto,  July 10
  • Neptune, September 5
  • Uranus, October 19

Observers are interested in oppositions because at this time, the planet at opposition is closest to Earth and so the planet’s observable features are easiest to see through telescopes.  The planet is in the sky all night and highest in the sky at midnight.

Photo credit:  Lowell Observatory

During an 1894 Mars opposition, Percival Lowell first began to document his later disproved discovery of “canals.”  While remote satellites give close-up images of the distant worlds, there are few more memorable events than seeing Jupiter, Saturn or Mars through a telescope.

In 2018, the three naked eye outer planets appear at opposition within an 80-day period:

  • Jupiter, May 8
  • Saturn, June 27
  • Mars, July 27

As they emerge from their solar conjunctions later in the year, they appear with Venus in the morning sky, including another Venus-Jupiter Epoch Conjunction.  More about these events as they approach.

For more information about sky watching events:

2017, May: View of Saturn

Saturn rises in the May sky later in the evening.  Early in the month it appears above the eastern horizon around 10 p.m.  While this planet does not dominate the sky in brightness, it is on of the wonders of the sky through a telescope.  Its extensive rings dazzle the eye.

On the morning of May 14, the waning gibbous moon appears about 4.5 degrees from Saturn.  The star Antares, appears 17 degrees to the upper right of Saturn.

On May 1, look for Venus near the eastern horizon, Jupiter near the western horizon and Saturn in the south.

For more information about the planets see:

2017: Venus as a Morning Star


Venus last appeared in the morning sky in 2015 and 2016, when it appeared with Mars and Jupiter.


Brilliant Venus zips into the morning sky during April  2017 and dominates the morning sky until year’s end.   During this morning appearance, Venus makes close appearances with the star Regulus and the planets Jupiter and Mars.


This chart shows the rising time of bright planets, the moon, and stars near the planets’ orbital plane (ecliptic) compared to sunrise as calculated from U.S. Naval Observatory data for Chicago, Illinois in the Central Time Zone.  Additionally, the times when Jupiter sets and Saturn sets are charted compared to sunrise.  On April 7, Jupiter is at opposition and it sets in the west at sunrise.  The time differences are also displayed for Civil Twilight, Nautical Twilight and Astronomical Twilight.  At Astronomical Twilight, the sky is as dark as it gets naturally.

The rising time of Venus is represented by the green line on the chart.  It enters the chart in mid-March, reaching its maximum rising time difference during the summer, and leaves the sky in early 2018.  Notice that during the summer months of this appearance of Venus, the brilliant planet rises well before the beginning of twilight.  It stands low in the eastern sky as the sky brightens.

As Venus appears earlier in the morning sky, Jupiter shines brightly in the western sky, until about May 20 when Jupiter sets as Venus rises. (Notice on the chart, Jupiter sets line crosses the Venus rises at May 20.)  After this date Jupiter sets before Venus rises.  Similarly, Saturn, while not as bright as Jupiter or Venus, reaches opposition on June 15, setting in the west as Venus rises in the eastern sky.  Venus appears in the eastern morning sky and Saturn appears in the western sky until about July 25 when Saturn sets as Venus rises.  After this date Saturn sets before Venus rises.

Later in the year, Venus appears near Regulus.  This occurs near the date when the rising lines of Regulus and Venus intersect.  The same occurs for Mars, Spica, and Jupiter.  As Venus moves back into bright sunlight later in the year, it appears near Mercury, Antares and Saturn, although they appear together during bright twilight and out of view for most observers.

Venus has a close conjunction with Mars on October 5, followed by a very close (Epoch) conjunction with Jupiter on November 13.

The moon passes Venus each month, as our nearest celestial neighbor moves through its celestial path.  Two dates (May 22 and July 20) are especially noteworthy when Venus and the moon appear about 3.5 degrees apart.

Inferior Conjunction


Venus moves between Earth and Sun on March 25, 2017; this is known as inferior conjunction.  Since Venus has a shorter orbital path and faster speed, it quickly moves into the morning sky.  The red line on the chart shows the division between morning and evening.  The line pointing from the earth to the sun indicates noon.  So at inferior conjunction, Venus rises with the sun, appears in the south at noon, and sets in the west at sunset.

Venus does not appear in the sky at midnight at mid-northern latitudes.  That occurs when a planet is opposite the sun in the sky as seen from Earth.  On the chart notice that the midnight line does not point toward Venus.

As Venus reaches this inferior conjunction, it passes above the sun.  Because it is north, above the sun, it rises earlier than the sun.  On conjunction morning it rises about 40 minutes before the sun.  On the rising chart above, it first appears on the chart on March 14, 11 days before it reaches conjunction!

Venus was last at inferior conjunction on August 25, 2015, 589 days between inferior conjunctions.

Greatest Brightness

The planet rapidly moves into the morning sky, rising earlier each morning.  It is very close to our planet and sparkles in the morning sky.  The brightness is from the proximity of the planet to Earth, its highly reflective clouds and the phase of the planet.  (Yes, Venus shows phases when viewed through a telescope.)  At this time Venus is about 170 times the moon’s distance, relatively close compared to other planets.


From April 15 through May 13, Venus appears brightest in our skies, with the mid-point on May 1, 2017.  This is shown with the GB (greatest brightness) designation on the rising chart above.


Update:  This image is from the beginning of the period of peak brightness.  Venus rises during twilight during maximum brightness during this appearance.


Venus continues to rise earlier each morning. On the morning of May 22, the crescent moon appears about 3.5 degrees from Venus.


Update May 22:  Venus and the moon appear together.

Greatest Elongation


Venus reaches its greatest angular separation (46 degrees) from the sun on June 3.  This is shown by the GE symbol (greatest elongation) on the rising chart above.  It rises about 2 hours before sun near the beginning of twilight.

Venus Dazzles Morning Sky

 Venus continues rising earlier as summer begins.


On July 14, Venus moves past Aldebaran.  The closest approach is about 4 degrees.


The Binocular View

More striking is the star cluster near Venus and Aldebaran: Hyades.  The Hyades cluster is about 2.5 times farther away than ruddy Aldebaran.  Through binoculars, Venus, Aldebaran and the jewel-like stars of the cluster sparkle against the black velvet of the  predawn sky. Several dozen stars can be seen.

To the unaided eye, the Hyades resemble a check mark or a letter “V” if Aldebaran is included.

Clusters, like the Hyades, are used to refine distance measuring techniques as well descriptions of the lives of stars.  These clusters are thought to form at approximately the same time.  Stars that burn their nuclear fuels faster convert into other stellar forms sooner, such as red giants and red super giants.  From these stellar models, the estimate of the sun’s total lifespan is about 10 billion years.

Over time these clusters break apart; the gravitational forces between the stars are not strong enough to keep the cluster together.  The stars go their own way in their orbital path around the galaxy.

Our sun was likely formed in such a cluster and is now a lone star since it has gone into its own orbit around the Milky Way galaxy.


On the morning of July 20, the crescent moon again appears with Venus.  The pair is separated by about 3.5 degrees.

In early August Venus rises about 3 hours before sunrise and begins to rise later each morning as displayed on the rising chart.  For the rest of the year, it loses about 30 minutes each month.


In late summer and early Autumn look for Venus and Sirius at the same time.  Both are about the same height (altitude) above the eastern horizon.  Venus stands in the east-northeast and Sirius appears in the southeast.  Only the sun and moon shine brighter than Venus and Sirius is the brightest star in the night sky. See this link to view the last time Venus and Sirius appeared together in the morning sky.


Venus continues its rapid eastward movement as compared to the stars and descent toward the sun’s glow, passing about a half degree from Regulus on September 20.  This pair rises about 2 hours before sunrise.


Over a month later, Venus passes Spica.  The gap is nearly 4 degrees.

Mars Conjunction


The first planetary conjunction of this appearance is with Mars.  On the morning of October 5, Venus passes 0.2 degrees from the Red Planet.  The planets are close on a few mornings before and after the conjunction.

Venus-Jupiter Epoch Conjunction


Another Epoch (close) Conjunction of Venus and Jupiter occurs before sunrise on November 13.  The distance is about .2 degrees.  This conjunction is visible during twilight as the pair rises about 70 minutes before the sun.

The next conjunction between the pair is November 24, 2019 with the next epoch conjunction on April 30, 2022.

Superior Conjunction

Venus continues its rapid descent into bright sunlight.  Conjunctions occur with Mercury, Antares and Saturn, but they occur in bright twilight, out of the view of most observers.


On January 9, 2018 passes behind the sun at its superior conjunction and reappears in the evening sky.

Lunar Conjunctions

The moon appears with Venus on the following dates:

April 23: 8 degrees


May 22: 3.5 degrees (See description in text)


June 20: 7 degrees

July 20: 3.5 degrees (See description in text)
August 19: 4.5 degrees
September 17: 6 degrees
October 18: 5.5 degrees

Other Images


Venus on April 2, 2017


Venus:  May 8, 2017 (Even visible from the brightest city lights)


Venus:  July 21, 2017

Venus provides a dazzling view of planetary, stellar and conjunctions during its morning appearance in 2017.

2017: Mercury in the Evening Sky


This chart shows the setting times of Mercury, other planets, and stars in the western sky compared to sun during 2017.  The vertical axis shows hours after sunset.  The horizontal axis shows the dates every seven days.

Mercury makes three appearances in the evening sky during 2017.  The brown curves on the chart above represent Mercury’s setting times compared to the times of sunset.  The three appearances peak around their greatest elongation dates:  April 1, July 29, and November 23.

The Geometry

The greatest elongation is the planet’s greatest angular separation from the sun.  As Mercury speeds around the sun it rapidly moves from the sun’s glare into the evening or morning sky and then back into the sun’s brilliance.

The planet revolves around the sun every 88 days.  Because our planet is revolving, yet at a slower speed and on a longer path, Mercury catches up and passes us every 116 days.


Mercury never appears no more than about 27 degrees from the sun and never appears in the sky at midnight from the mid-northern latitudes.  So it is in the sky mainly during the daytime and sometimes during twilight.  The chart above shows Mercury on April 1, 2017, when it is at its greatest elongation or maximum separation (19 degrees) from the sun.  This chart shows the sun and Mercury at noon, if the sky were dark.  The red line represents Mercury’s invisible orbital path.

Hold a ruler (12 inches) at arms length.  If the sun were at one end, Mercury would appear near the other end when it is at its greatest separation from the sun.


Mercury passes behind the sun on March 6, 2017.  It is invisible because it is hidden in the sun’s glare.  The planet then moves into the evening sky, east of the sun, until it reaches its greatest separation from the sun on April 1.  It then rapidly moves into the sun’s glare and passes between Earth and sun  (inferior conjunction).  Mercury then moves into the morning sky, west of the sun.  After reaching its greatest elongation it moves back into the sun’s brilliance reaching superior conjunction.  The chart above shows the configurations if the earth were stationary.

The April 1 Elongation


Our view of the planet is further complicated by our seasonal view of the plane of the solar system, known at the ecliptic.  The chart above shows the plane and Mercury’s orbit at the planet’s greatest elongation (19 degrees), just after sunset.  The narrow elongation would be particularly challenging to see, but the angle the ecliptic makes with the western horizon is very large.  During spring evenings, the ecliptic makes its highest angle with the horizon.  Venus and Mercury stand very high in the western sky during these times.  In the morning, the ecliptic makes its sharpest angle on autumn mornings.

On the evening of April 1, Mercury sets over 100 minutes after sunset.  Astronomical twilight ends 96 minutes after sunset, and nautical twilight, 61 minutes.  At astronomical twilight, see the chart at the top of this article, the sky is as dark as it will ever get naturally.  At nautical twilight, the horizon is visible, so that mariners can take measurements of star’s heights (altitudes) above the horizon.

So at this appearance, Mercury can be seen low in the western sky.  First locate the planet with binoculars, then try with optical help.  Look for Mercury a week before and after April 1.

The July 29 Elongation


At the next greatest elongation on July 29, the angular separation is 27 degrees, but the angle of the ecliptic is very unfavorable.  Mercury sets about 60 minutes after sunset, but nautical twilight occurs 70 minutes after sunset.  Astronomical twilight occurs nearly 115 minutes (almost two hours) after sunset.  Mercury is less than 15 degrees at sunset.  This is likely a binocular or small telescope only apparition, from the unfavorable position of the ecliptic.

The November 23 Elongation


Similarly, the November 23rd apparition has unfavorable observing conditions.  At sunset, the planet is less than 10 degrees above the horizon and sets nearly 70 minutes after sunset.  Saturn is 4 degrees above Mercury and sets nearly a 30 minutes after the speedy planet.  Nautical twilight occurs at nearly the same time as Mercury sets and astronomical twilight is nearly 35 minutes later.  Like the summer appearance, Mercury can be seen with optical aid.

Mercury appears in the western evening sky three times during the year.  Because of favorable seasonal circumstances, the April 1, 2017, view is the best of the year.

2017, February: Sky Watching

Orion Nebula (NASA Photo)

Orion Nebula (NASA Photo)

The constellation Orion is visible high in the southern skies during the early evening hours of February.  It is easily recognizable by its three stars of nearly equal brightness that mark his belt.  Within his sword is a gently glowing nebula.  Through binoculars or a small telescope it appears as a greenish cloud with stars in it.  The Hubble Space Telescope gathered the light of this distant stellar nursery to make this colorful, dynamic image shown above.


The length of daylight increases by 70 minutes this month.  The sun rises and sets farther north and appears 9 degrees higher at noon by month’s end.  The rising and setting directions move about 12 degrees northward during the month.  In the Chicago area, the sun rises before 7 a.m. the first time this year on February 5.

There is an annular solar eclipse on February 26, although it is only visible from the southern hemisphere (Pacific Ocean, South America, Atlantic Ocean, and Africa.)


NASA Photo

NASA Photo

Phase Date/Time Moon rise Moon set
First Quarter 02/03/17 (10:19 p.m.) 10:51 a.m. 11:31 p.m.
Full Moon 02/10/17 (6:33 p.m.) 5:13 p.m. 7:10 a.m. (02/11/17)
Last Quarter 02/18/17 (1:33 p.m.) 12:19 a.m. 10:52 a.m.
New Moon 02/26/17 (8:58 a.m.) 6:34 a.m. 5:55 p.m.
Times are Central Standard Time for Chicago, Illinois, from US Naval Observatory calculations.
(For mjb & afb)

There is a penumbral lunar eclipse on the evening of February 10, although the moon will not display is classic reddish eclipse color.  During this eclipse the moon passes through the earth’s outer shadow that is quite bright.  Casual observers will not see much change in the moon’s brightness during the eclipse.  The eclipse is visible across most of the planet except for eastern Asia and Australia.  In the Chicago area, the moon rises in the in the east-northeastern sky at 5;13 p.m. CST with the eclipse in progress.  As the moon rises higher, the eclipse progresses.  The maximum eclipse is at 6:33 p.m. CST when the moon is officially full.  (See the time of the full moon above.) The eclipse ends at 8:53 p.m. CST.

Evening Sky


Gleaming Venus shines brilliantly from the western sky as the month opens.  Dimmer Mars is about 5.5 degrees to the upper left of Venus and the crescent moon is another 11 degrees above Mars.

The planets are closest on February 3, still over 5 degrees apart.  Venus does not pass Mars; after this closest appearance, Venus rapidly moves toward the sun’s brilliance.

Beginning February 4 and lasting for nearly a month, Venus reaches its greatest brightness, with the mid-point date on February 18.  This period of greatest brilliancy occurs when Venus and Earth are near each other.  During this time, the distance to Venus is about 39 million miles, about 160 times the moon’s distance.  Venus is nearing its inferior conjunction when it passes between Earth and the sun, so it appears larger when viewed through a telescope than when it is near its superior conjunction on the far side of the sun.  This combined with its highly reflective clouds makes it appear to be the brightest star in the sky.

For More about Venus in the evening sky and its close approach to Mars, see these articles:


By month’s end, the moon appears again in the western sky after sunset.  On February 28, it appears about 10 degrees to the lower right of Venus with Mars 12 degrees to the upper left of Venus.

Morning Sky

Meanwhile, Jupiter shines brightly from the southern skies with the star Spica.  The pair rises in the southeast at around 11 p.m. and are well placed in the southern sky before sunrise.  Jupiter’s proximity to Spica is part of a triple conjunction — that is, Jupiter passes Spica three times during a single apparition.  Jupiter first passed Spica on January 20, by about 3.5 degrees.

During early February, Jupiter appears to begin to backup, retrograde, and passes Spica again on February 23.  The third conjunction occurs on September 9.


The waning gibbous moon joins Jupiter and Spica on the morning of February 15.  The moon is 3.5 degrees from Jupiter and Spica is nearly the same distance below Jupiter.  For more about Jupiter’s triple conjunction with Spica, see this article:


Saturn is easier to locate in February.  It rises at about 4 a.m. at the beginning of the month.  It rises earlier each day.  By February 20, the moon appears about 6 degrees to the upper right of Saturn.  On the next morning the moon appears about 6 degrees below Saturn.

February offers four bright planets and a host of bright stars for easy viewing.  Dress warmly, step outside and take a look.

2016, November 3: Venus, Saturn, Moon & Mars


Brilliant Venus shines from the western sky this evening as seen from the Chicago area.  The moon, overexposed in the image, appears about 10 degrees to the upper left of Venus.  Dimmer Saturn is 6 degrees to the right of Venus.  The red planet Mars is 36 degrees to the upper left of Venus.  During the month, watch Venus get closer to Mars.  For more about the planets see the articles linked above.

2017: Evening Planets


(All charts and times are calculated for Chicago, Illinois in the Central Time zone.)

The evening sky in 2017 presents the five naked eye planets for easy viewing.  The year begins with Venus and Mars shining brightly in the western sky during early evening hours.

The chart above shows the times that planets, moon, and bright stars, near the plane of the solar system, set compared to sunset.  This activity occurs in the western sky.  Moon set is represented by circles;  two days each lunar cycle are labelled with their dates.  The exceptions are the Jupiter Rises and Saturn Rises lines.  Their graphs indicate when those two planets rise in the eastern sky.  When the planets rise at sunset earth is between the planet and the sun.  The planet is at opposition.  When the sun sets in the west, the planet rises in the east.  The planet is south at midnight and sets in the west at sunrise.  Jupiter is at opposition on April 7, Saturn on June 15.

Venus and Mars


These two planets are well placed in the western evening sky for easy observation on New Years Day. Venus sets nearly 4 hours after sunset and Mars follows about an hour later.  Venus and the Moon are 4 degrees apart with Mars about 12 degrees to the upper left of Venus. During January, Venus and Mars appear to move closer together as the setting lines of the two planets begin to converge.

On January 12, Venus reaches is greatest angular separation from the sun (47 degrees) and sets 4 hours after the sun.

On February 3, 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.  On this date, Venus enters a 30-day period when it is at its maximum brightness with the greatest brilliance date of February 17.  Venus dazzles the late winter sky in the west with the bright stars of Orion, Canis Major, Canis Minor, and Auriga shining in the southern sky.

Image from February 3, 2017

The planets then separate with Venus rapidly moving into the sun’s brilliant glare passing its solar inferior conjunction on March 25 and moving into the morning sky.

Mars is on a slow trail of descent into the sun’s glare that ends at conjunction on July 26 and the planet enters the morning sky.

On March 1, the moon appears 5 degrees to the lower left of Mars with Venus 13 degrees to the lower right of Mars.

In late April, Mars moves through the region of the sky with Aldebaran (Taurus) and two bright star clusters (Pleiades and Hyades).  This article explains more about Mars’ movement and the Venus-Mars encounter.


Mercury’s best evening appearance of the year occurs during Spring this year.  On April 1, this speedy planet reaches its greatest angular separation from the sun (19 degrees) and sets 100 minutes after sunset.


A few nights earlier, the waxing crescent moon appears 10 degrees to the left of Mercury and Mars is 16 degrees to the upper left of Mercury.  (The chart shows the sky 70 minutes after sunset.  For other observers at mid-northern latitudes determine your local sunset time and 70 minutes to get a similar view.)  At this time Mercury is less than 6 degrees in altitude.  Find a clear horizon, free from houses, buildings and trees.  Use binoculars to locate Mercury; then locate it without optical aid.

Mercury and Mars on March 28, 2017.


Jupiter enters the evening sky in the east when it appears at opposition on April 7.  During the spring it appears in the eastern evening sky.  It “enters” the setting chart shown at the top of this article on June 22 when it sets 5 hours after sunset.  Jupiter is near the bright star Spica.  This article provides more details about its conjunctions with Spica during its 2016-2017 appearance.

A conjunction occurs as Jupiter and Spica disappear into the sun’s glare as Jupiter heads for its solar conjunction (October 27).   At the planet-star conjunction, shown in the chart above, the objects are separated by 3.3 degrees.


On the planet setting chart, the “Saturn Rises” circles indicate that the planet is rising in the east at those times.  When it rises in the east at sunset, it is at opposition.


Saturn appears in the south during the mid-summer evenings.  On August 2, the waxing gibbous moon appears about 4 degrees from the Ringed Wonder and Antares is about 13 degrees away from the planet.

The Saturn setting line then enters the chart again in early September when it is setting less than 5 hours after sunset.


On November 20, the waxing crescent moon appears near Saturn when the pair is low in the west, setting abut 110 minutes after sunset.

Other dates when the moon appears near Saturn:

  • August 29
  • October 23


NASA Photo

NASA Photo

Full Moon Dates (Central Time)

  1. January 12
  2. February 10
  3. March 12
  4. April 11
  5. May 10
  6. June 9
  7. July 8
  8. August 7
  9. September 6
  10. October 5
  11. November 4
  12. December 3

As a closing note:  In the U.S. Daylight Saving Time runs from March 12 (2 .m. local time set clocks forward) to November 5 (2 a.m. local time set times back).

End Notes: Twilight Definitions

Civil twilight is defined to begin in the morning, and to end in the evening when the center of the Sun is 6 degrees below the horizon. This is the limit at which twilight illumination is sufficient, under good weather conditions, for terrestrial objects to be clearly distinguished. In the morning before the beginning of civil twilight and in the evening after the end of civil twilight, artificial illumination is normally required to carry on ordinary outdoor activities.

Nautical twilight is defined to begin in the morning, and to end in the evening, when the center of the sun is  12 degrees below the horizon. At the beginning or end of nautical twilight, under good atmospheric conditions and in the absence of other lighting, general outlines of ground objects may be distinguishable. During nautical twilight the illumination level is such that the horizon is still visible even on a Moonless night.

Astronomical twilight is defined to begin in the morning, and to end in the evening when the center of the Sun is 18 degrees below the horizon. Before the beginning of astronomical twilight in the morning and after the end of astronomical twilight in the evening, light from the Sun is less than that from starlight and other natural sources. For a considerable interval after the beginning of morning twilight and before the end of evening twilight, sky illumination is so faint that it is practically imperceptible. (Source)