Day: January 1, 2019

2019: Saturn’s Year in Sagittarius

Magnificent Saturn (NASA Photo)

During 2019, Magnificent Saturn has a dramatic display in the southern skies throughout the year.  It is headed toward a Great Conjunction with Jupiter in 2020.  During this appearance Venus passes the planet twice.

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Saturn in eastern Sagittarius (Constellation image from Starry Night Pro)

Saturn appears in front of the stars of Sagittarius, although a little farther east compared to its location in 2018.  It appears to the upper left of the famous stars of The Teapot of Sagittarius.  To the unaided eye, the planet appears as a bright yellow-orange star.

Saturn: The Apparition Begins at Conjunction

Saturn revolves around the sun slowly, one orbit in nearly 30 Earth years.  The planet does not move very far against the background of stars.  Since it is heading toward a region of dim stars, the starry background is better known by their catalog names than their common names. Saturn starts its apparition about 4° to the upper left of Nunki (σ Sag, m = 2.0).  During the apparition, the Ringed Wonder moves beneath three other stars in the constellation: Pi Sagittarii (π Sgr, m = 2.9), Omicron Sagittarii (ο Sgr, m = 3.8), and Xi2 Sagittarii (ξ2 Sgr, m = 3.5). (The “m” number indicates the brightness of a star.  The lower the number the brighter the star.  Venus has a negative number because of its brilliance.  The stars listed here are dimmer stars, visible to most observers, but they are not easily seen near street lights.  A binocular helps to distinguish them in the sky.)

Saturn at conjunction, January 1, 2019.

Saturn’s apparition begins with its solar conjunction on January 1, 2019.  Saturn is behind the sun and largely invisible to us.  It rises with the sun, crosses south near noon, and sets with the sun in the west.  As Earth, moving much faster than Saturn, begins to close the space to Saturn, the Ringed Wonder appears in the morning sky.

The morning sky during 2019. The chart shows the rising time of planets, bright stars near the planets’ paths and the moon (circles), along with the three phases of twilight. White boxes indicate conjunctions.

As the chart above indicates, Saturn slowly rises into the morning sky, rising earlier each day.  By January 11, Saturn rises at Civil Twilight, when the sun is 6° below the horizon.  The sky is bright at 30 minutes before sunrise.  Eleven days later it rises at Nautical Twilight, about 60 minutes before sunrise, when the sun is 12° below the horizon.  Thirty minutes later it is low in the southeast, visible with a binocular.  On February 3, it rises at the beginning of twilight (Astronomical Twilight).  It becomes easier to see without optical assistance.  It joins brilliant Morning Star Venus and bright Jupiter in the southeast before sunrise.

The First Venus Conjunction

On February 18, Venus passes 1.1° to the upper left of Saturn.  Jupiter is far to the upper right of Saturn.

This chart displays Saturn’s apparent motion during 2019

All the objects beyond Earth’s orbit display an unusual pattern midway through their apparitions, retrograde motion.  The planet appears to move backward against the stars.  Our ancestors were captivated with explaining this unusual motion, especially when Earth was considered to be at the center of the universe.  Today we understand this is an illusion of our faster moving Earth passing the slower moving outer planets.  Retrograde motion occurs for Mercury and Venus as well, but it is from their faster speeds around the sun.  The chart above shows the retrograde pattern of Saturn in eastern Sagittarius.

This chart shows more detail in Saturn’s retrograde motion, along with the dimmer background stars. Two conjunctions with Venus are displayed.

The chart above shows a more detailed view of Saturn’s motion against eastern Sagittarius, along with the two conjunctions with Venus.

Saturn at Morning Quadrature

Saturn continues to rises earlier but gently moves eastward along its celestial path and against the starry background.

Saturn appears 90° west of the sun on April 9, 2019. Look for it in the south near sunrise.

By early April Saturn is 90° west of the sun, appearing in the south near sunrise. The planet rises at about 2:30 a.m. CDT.  It is about 26° up in the south as sunrise approaches.  By late April, Earth closes in on Saturn and the planet seems to stop moving eastward and it begins to retrograde on April 29.  (See the two time-lapse charts above that show Saturn’s apparent motion compared to the starry background.)

Saturn at Opposition

By mid-May, Saturn is rising around midnight (CDT).

Saturn at Opposition, July 9, 2019

Earth is rapidly catching Saturn.  The planet continues to rise earlier and on July 9, it rises in the southeast at sunset  The sun and Saturn are on opposite sides of Earth.  When the sun sets, Saturn rises.  At midnight, Saturn is south, opposite 12 hours when the sun is south (at noon).  Saturn sets in the southwest at sunrise. Opposition.  This occurs about in the middle of the planet’s retrograde motion.

Saturn then rises before sunset appearing higher in the southeast as the sky darkens.  By mid-September Saturn’s retrograde motion slows and the planet stops moving westward compared to the starry background on September 17.

Saturn is in the south near sunset on October 7, 2019

A few weeks later, Saturn appears 90° east of the sun, meaning it’s in the south at sunset.

A Second Venus Conjunction

Saturn is then farther west at sunset; it is heading toward its solar conjunction.

Venus passes Saturn on December 10, 2019.

As Saturn heads towards that solar conjunction in early 2020, Venus, during its evening apparition, passes 1.8° to the lower left of Saturn in the southwest.  This occurs on December 10, 2019.  Look about one hour after sunset.

Saturn Toward Conjunction

Saturn then begins to disappear into bright evening twilight in the western sky, the reverse of how it appeared in the morning sky. The events:

  • December 19, Saturn sets at Astronomical Twilight.
  • December 28, Saturn sets at Nautical Twilight.
  • January 5, 2020, Saturn sets at Civil Twilight.
Saturn returns to its solar conjunction on January 13, 2020.

Saturn then seems to move behind the sun for its solar conjunction, January 13, 2020.

In Saturn’s next apparition, Jupiter passes it in late December 2020.  This apparition ends with Jupiter about 17° west of Saturn.

Saturn and the Moon

The moon appears near Saturn several times during the apparition.  If you observe Saturn just once a month when the moon is nearby, you’ll see a complete cycle of moon phases.

Before Opposition Separation After Opposition Separation
February 2 3.1° July 15 1.8°
March 1 3.2° August 11 3.3°
March 29 3.0° September 7 5.5°
April 25 2.7° October 5 2.9°
May 23 5.7° November 1 3.7°
June 18 1.3° November 29 1.9°
December 27 5.6°