2017: Evening Planets


17-pm-setting

(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

ven_mars_lune_170101

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

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.

merc_mars_lune_170329

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

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.

Saturn

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.

sat_lune_170802

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.

sat_lune_171120

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

Moon

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)

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