2023, September 25: Moon Approaches Saturn, Bright Planets

Astronomy, Sky Watching

September 25, 2023: After sundown, the gibbous moon approaches Saturn.  Venus, Mercury, Jupiter, and Saturn are visible during nighttime hours.

2019, March 1: This morning the moon is moon is nearly 3 degrees to the upper right of Saturn, partly obscured by a cloud.
Photo Caption – 2019, March 1: This morning the moon is moon is nearly 3 degrees to the upper right of Saturn, partly obscured by a cloud.

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by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 6:41 a.m. CDT; Sunset, 6:43 p.m. CDT.  Check local sources for sunrise and sunset times. Times are calculated by the US Naval Observatory’s MICA computer program.

Sunrise approaches
Photo Caption – Sunrise approaches, July 3, 2022.

As the season changes astronomically, daylight and darkness are nearly equal.  This does not occur on the equinox because of the definition of sunrise and sunset and that sunlight is refracted or bent by the thick air along the horizon.  Today daylight’s length is twelve hours, two minutes.

Summaries of Current Sky Events
Summary for Venus as a Morning Star, 2023-24

Here is today’s planet forecast:

Morning Sky

2023, September 25: An hour before sunrise, Venus and Mercury are in the eastern sky with the Sickle of Leo.
Chart Caption – 2023, September 25: An hour before sunrise, Venus and Mercury are in the eastern sky with the Sickle of Leo.

Over three hours before sunrise, Venus rises in the eastern sky and Saturn is low in the west-southwest.  On October 10th, Saturn sets as Venus rises, when the two planets are 180° apart in the sky.  Saturn reappears in the eastern morning sky next year.  Venus passes by while they are in bright morning twilight during April. 

By an hour before sunrise this morning, brilliant Venus is “that bright star” in the east, less than one-third of the way up in the sky from the horizon to overhead.  The Morning Star is stepping eastward toward Regulus, passing by October 9th. It crosses into Leo this morning.

To watch Venus’ eastward motion, look for the star Omicron Leonis (ο Leo on the chart) with a binocular. The planet is 4.8° to the upper right.  Each morning Venus appears closer to the star passing by October 2nd.

Find the Sickle of Leo, a backwards question mark pattern that includes Regulus.  The shape is an agricultural implement for cutting grain, a handle with a sharp, curved blade.

Mercury is presenting its best morning display of the year, over 5° up in the east and 14.6° to the lower left of Regulus.  The speedy planet grows brighter each morning as it departs, returning to bright morning twilight. This morning it is the third brightest starlike body, after Venus and Jupiter.

Find a clear horizon looking toward the east to find Mercury.  An elevated structure or hilltop helps the view.

2023, September 25: Jupiter is in the west-southwestern sky during morning twilight.
Chart Caption – 2023, September 25: Jupiter is in the west-southwestern sky during morning twilight.

At this hour bright Jupiter is over halfway up in the west-southwest.  It retrogrades in front of Aries, 13.2° to the left of Hamal, Aries brightest star, 11.2° to the upper right of Menkar, Cetus’ nostril, and 16.4° to the lower right of the Pleiades star cluster, part of Taurus.

Jupiter’s retrograde is carrying it westward compared to the referenced stars.  Watch it move closer to an imaginary line from Hamal to Menkar.

Evening Sky

Mars
The Red Planet from the Mars Global Surveyor shows the effects of a global dust storm (NASA)

Dim Mars is not easily visible as it hides in bright evening twilight, setting about forty minutes after the sun.

2023, September 25: After sundown, the Saturn and the moon are in the southeast.
Chart Caption – 2023, September 25: After sundown, the Saturn and the moon are in the southeast.

The moon is heading toward its Full moon phase on the 29th.  This evening the lunar orb (84% illuminated) is less than 20° above the southeast horizon and over 15° to the right of Saturn.

The moon’s light washes out the dimmer starfields across the sky that can be seen with a binocular.

During the night as the wheel of the sky seems to spin, Saturn is in the south four hours after sunset and appears low in the west-southwest as Venus rises in the morning.

Bright Jupiter rises in the eastern sky less than two hours after sundown.  As the calendar day ends, the Jovian Giant is in the east-southeast.  By tomorrow morning, it is in the west-southwestern sky.

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