2023, September 8: See the Moon with a Star Cluster

Photo Caption – 2022, August 19: Mars, the moon, and Pleiades,


by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 6:24 a.m. CDT; Sunset, 7:13 p.m. CDT.  Check local sources for sunrise and sunset times. Times are calculated by the US Naval Observatory’s MICA computer program.

Summaries of Current Sky Events

Here is today’s planet forecast:

Morning Sky

Chart Caption – 2023, September 8: Jupiter is high in the south-southwest before sunup.

An hour before daybreak, bright Jupiter is high in the south-southwest.  It is the brightest star in the region, but dimmer than Venus and the crescent moon.

The Jovian Giant is retrograding in front of Aries, 13.6° to the lower left of Hamal, the constellation’s brightest star, and nearly 16° to the lower right of the Pleiades star cluster.

Photo Caption – Jupiter (NASA Photo)

Earlier this morning at 2:14 a.m. CDT, Jupiter’s Great Red Spot is at the center of the planet in the southern hemisphere.  Use a telescope with magnifications of at least 150x to see the planet’s long-lived atmospheric disturbance. Look for Europa, one of Jupiter’s four largest satellites in front of the planet appearing to the lower left of the Red Spot.

Chart Caption – 2023, September 8: The moon is near Castor’s foot before sunrise.

The crescent moon, 25% illuminated, is over halfway up in the eastern sky.  It is at Castor’s foot, designated by Propus – the toe – and Tejat Posterior – the heel – and below Elnath and Zeta Tauri – the Bull’s horns.

Chart Caption – 2023, September 8: Find the star cluster Messier 35 near the moon with a binocular.

A star cluster, cataloged as Messier 35 (M 35 on the chart) is nearly between the toe and the lunar crescent.  The moon, star cluster, and foot comfortably fit into a binocular field of view. The cluster is known as a galactic or open cluster, lying in the plane of the Milky Way.  It is similar to the Pleiades.

In the sky, the star cluster, containing a few hundred stars, looks about the same size as the moon, but the stellar bundle is nearly 3,000 light years away, about seven times the Pleiades distance. The apparent size and distance indicate that the cluster is nearly 25 light years across.

For sky watchers in darker locations without the persistent glow of outdoor lighting, the cluster might be visible to the unaided eye, but the optical assist is needed in urban and suburban settings.

Chart Caption – 2023, September 8: Venus, Sirius, and Procyon are in the eastern sky before daybreak.

Brilliant Venus is in the eastern sky at this hour.  After passing between Earth and the sun on August 13th, the planet has been rushing into the eastern predawn sky, rising about five minutes earlier each morning compared to sunrise.  This morning it appears above the horizon nearly three hours before the sun rises. 

Find it over 15° up in the east during morning twilight.  It is over 40° to the left of Sirius, night’s brightest star.  Look for them at about the same altitude during the remainder of the month.

Procyon is a little higher in the sky, above a line from Venus to Sirius.

Photo Caption – Mercury as Never Seen Before. (NASA photo)

Mercury is racing into the morning sky, but this morning it rises less than 15 minutes before the sun.  It appears in the eastern sky earlier each morning.  Begin looking for it in about a week.

 Evening Sky

These side-by-side images of Mars, taken roughly two years apart, show very different views of the same hemisphere of Mars. Both were captured when Mars was near opposition, which occurs about every two years, when Earth’s orbit catches up to Mars’ orbit. At that time, the Sun, Earth, and Mars fall in a straight line, with Mars and the Sun on “opposing” sides of Earth. (NASA Photo)

Mars is on a slow slide into bright twilight.  Because it revolves around the sun at about half Earth’s speed, the Red Planet’s motion against the sky seems slower than Jupiter and Saturn. It does not reach solar conjunction until November.

Chart Caption – 2023, September 8: Saturn is in the southeastern sky during the evening.

Saturn rises before sunset and by two hours after sundown, the Ringed Wonder is nearly 25° up in the southeast.  While it is as not as gleamingly bright as Venus or Jupiter, it is brighter than most stars this evening.

Saturn is retrograding, appearing to move westward, in front of Aquarius, 8.9° to the upper right of Skat, meaning “the leg,” and 9.1° to the right of Lambda Aquarii (λ Aqr on the chart).

As the wheel of the sky seems to turn, the Ringed Wonder is in the south about five hours after sunset, and it sets in the west-southwest about an hour before sunup.

Jupiter rises over two hours after sunset and as the midnight hour approaches the Jovian Giant is in the eastern sky.


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