2023, September 26: Look for Leo’s Sickle, Saturn-Moon Conjunction

Photo Caption – Venus, Jupiter, Mars, Regulus September 26, 2015


by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 6:42 a.m. CDT; Sunset, 6:41 p.m. CDT.  Check local sources for sunrise and sunset times. Times are calculated by the US Naval Observatory’s MICA computer program.

Today nighttime is longer than daylight.  It is only one minute today, but by mid-march daylight’s length slips to eleven hours, seven minutes.

This year, there is no single day when daytime and nighttime are precisely equal at Chicago’s latitude. The equinox occurred three days ago.  The sun shines more directly toward Earth’s southern hemisphere.

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

Here is today’s planet forecast:

Morning Sky

Chart Caption – 2023, September 26: Venus, Mercury and the Sickle of Leo are in the eastern sky during morning twilight.

Over three hours before daybreak, Venus rises in the eastern sky and Saturn shines from the west-southwest. The two planets are 167° apart.  By October 10th, they are 180° apart and Saturn sets as Venus rises.  After this planet-to-planet opposition, Saturn sets before Venus rises.  Saturn returns to the morning sky during April 2024 as Venus slides into morning twilight as it approaches superior conjunction during June.

This morning one hour before sunrise brilliant Venus and Mercury are in the eastern sky with the Sickle of Leo.  Venus is “that bright star” in the east that can be mistaken for lights on an airplane. At this hour it is over 25° above the horizon and it can be tracked into brighter twilight near sunrise.

The planet is stepping eastward toward Regulus, Leo’s brightest star.  Their conjunction occurs October 9th.  This morning, the gap is 10.6°.  As this conjunction approaches, watch the planet approach and pass the star Omicron Leonis (ο Leo on the chart). Use a binocular to track Venus as it passes the star October 2nd.  This morning the gap is 4.1°.

Omicron is likely washed out by outdoor lighting in urban and suburban settings.  Sky Watchers with darker skies can see the star without the optical assist.

Bright Mercury is about 5° above the eastern horizon and 16.0° to the lower left of Regulus.  It brightens and retreats into brighter twilight each morning.  The planet is putting on its best morning celestial show of the year. It is bright enough to be seen without a binocular, but the optical boost helps with its initial identification.  The challenge is to find a clear horizon without clouds and obstacles.  An elevated structure or hilltop helps the view.

Regulus is part of the constellation that resembles a backwards question mark.  It has been traditionally named the “Sickle of Leo”.  The pattern resembles a sickle, an agricultural tool for harvesting grain.

The sickle outlines the head and mane of the westward-facing Lion.  The haunches and tail, marked by a triangle, are too low for easy viewing.

Leo is in the sky some time during the night until nearly summer’s mid-point.  During autumn it is slightly farther westward each morning.  Around the end of February, it appears low in the eastern sky after sunset and then each night starts the night farther westward.  By May evenings, it is in the south at sundown.  During July, the majestic Lion begins the nights low in the west-northwest, sliding into bright sunlight, reappearing in the morning sky next September to repeat the cycle.

Chart Caption – 2023, September 26: Bright Jupiter is in the west-southwest during twilight, nearing an imaginary line from Hamal to Menkar.

This morning bright Jupiter is in the west-southwest, over halfway up in the sky from the horizon to overhead.  It continues to retrograde in front of Aries, 13.2° to the left of Hamal, the constellation’s brightest star, 11.2° to the upper right of Menkar, the Sea Monster’s nostril, and 16.4° below the Pleiades star cluster, part of Taurus.

With this retrograde – the appearance that a distant planet moves westward compared to the starfield – Jupiter seems to be moving toward an imaginary line from Hamal to Menkar.  Watch the planet inch toward that line during the next several days.

Evening Sky

Photo Caption – 2007, December 1: Late winter in the northern hemisphere shows clouds above the northern polar cap and some above the southern cap. (NASA Photo)

Mars, considerably dimmer than we might expect, is sliding into bright sunlight, setting about forty minutes after the sun.  It passes behind the central star on November 18th.  It then slowly climbs into the morning sky.  Mercury passes it on January 27th, followed by a conjunction with Venus on February 22nd.

Chart Caption – 2023, September 26: Saturn and the gibbous moon are in the southeast after sundown.

An hour after sundown, the gibbous moon (91% illuminated) is about 20° above the southeast horizon and 3.6° to the lower right of Saturn.

The moon is waxing toward the Full moon or Harvest Moon phase, occurring on the morning of the 29th.  Besides the seasonal name, there is an astronomical effect that occurs.  See the article about the Harvest Moon effect.

This moonlight washes out the dimmer stars in the region and across the sky.  It might be necessary to shield your eyes from the lunar light to see Saturn.

During the night, Saturn and the moon seem to move westward compared to the horizon.  By four hours after sundown, they are in the south and low in the west-southwest about three hours before sunup when Venus rises tomorrow morning.

Jupiter rises one hundred, four minutes after sunset.  As the calendar day ends, it is nearly halfway up in the east-southeast, and it is visible in the west-southwest tomorrow morning.



Leave a ReplyCancel reply