2023, September 11:  See Morning Double Crescents

Photo Caption – Venus, Mars, Moon, September 10, 2015


by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 6:27 a.m. CDT; Sunset, 7:07 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

Summary for Venus as a Morning Star, 2023-24

Here is today’s planet forecast:

Morning Sky

Chart Caption – 2023, September 11: Venus and the lunar crescent are in the eastern sky. Regulus is to Venus’ lower left.

This morning the eastern sky is full of bright stars than shine in the southern sky during winter’s evenings.  This includes Orion’s Betelgeuse and Rigel, Castor and Pollux as the Gemini Twins, Aldebaran, Procyon, and Sirius.  Brilliant Venus and the crescent moon tops off the view.

Two crescents are visible this morning.  The easiest to see is the lunar crescent.  Eleven per cent illuminated, the moon is less than one-third of the way up in the east.

Photo Caption: 2022, June 24: The crescent moon with earthshine before sunrise.

Look for earthshine on the night portion of the moon.  This is from sunlight reflected from Earth’s oceans, clouds, and land that gently illuminates the lunar night.  From the moon, Earth is quite bright in the sky.  The nearly-Full Earth shines brightly in the lunar sky and it softly lights up the lunarscape.

Photograph earthshine with a tripod-mounted camera and exposures up to a few seconds, depending on the camera’s settings.  Many photos of earthshine that appear here are exposures of less than one second.

The second crescent is Venus.  While not visible to the unassisted eye, the planet displays a thin crescent, 20% illuminated, through a spotting scope or telescope. It resembles a miniature lunar crescent, but without the moon’s features.

Both crescents are tilted toward the sun with their cusps or horns pointed away from the central star.  The terms waxing and waning are not used for Venus.  The planet recently emerged from inferior conjunction and its phase is growing, but it looks like a waning crescent moon. The Venusian phase continues to grow during its appearance, but this morning’s moon phase is described as waning.  For Venus, the term “morning” precedes any phase description, such as morning crescent, morning half phase, or morning gibbous phase.  Similarly, when the planet is an Evening Star in the west, the descriptor “evening” precedes the phase shape.

Look for the star Regulus, Leo’s brightest star and meaning “the prince,” over 5° up in the east-northeast and over 18° to the lower left of Venus.  Each morning, Venus moves closer to the star passing by October 9th.

Chart Caption – 2023, September 11: Through a binocular, the crescent moon appears with the Beehive star cluster (M 44).

With a binocular find a star cluster known as the Beehive or Praesepe – meaning manger – commonly known as Messier 44 (M 44 on the chart).  Place the moon toward the left of the field of view.  The star cluster is toward the right, along with two donkeys – Asellus Borealis and Asellus Australis – that could be imagined as eating from the manger. The Praesepe may have nearly 400 stars in its boundaries. A few dozen are visible through the binocular.

From a location away from the glow of perpetual outdoor lighting, the cluster appears as a tiny cloud to the unassisted eye, between Castor and Pollux and Regulus among Cancer’s stars.  Its composition was not known until the first recorded telescopic view was made in 1610.

The stellar bundle is known as an open or galactic cluster.  The type is known to reside in the Milky Way’s plane.  The most famous is the Pleiades or Seven Sisters to the upper left of Jupiter this morning.  The Praesepe appears larger in the sky than the moon and at a distance of 590 light years, the cluster is about 15 light years across.  This is smaller than Messier 35, the cluster at Castor’s foot, where the moon appeared three mornings ago.

Chart Caption – 2023, September 11: Venus, Sirius and Procyon are in the eastern sky before sunrise. Venus and Sirius are about the same altitude – height above the horizon.

Venus and Sirius, night’s brightest star also known as the Dog Star, are about the same altitude – height above the horizon.  Sirius is in the southeast during morning twilight.  This continues until the end of the month.

Sirius is about 40° away from the plane of the solar system, known as the ecliptic.  No bright planet or the moon appears near the star.  The result is that the brightest planet and the brightest star are at the same altitude in the eastern predawn sky.

Procyon – meaning “before the dog” because it rises about 30 minutes before Sirius at the mid-northern latitudes – is above an imaginary line from Venus to Sirius.

Chart Caption – 2023, September 11: Jupiter is high in the south-southwest near Hamal, Menkar, and the Pleiades star cluster.

Bright Jupiter is high in the south-southwest about an hour before daybreak.  It is retrograding – appearing to move westward compared to Aries – 13.6° to the lower left of Hamal – the Ram’s brightest star – and 11.3° to the upper right of Menkar, the Sea Monster’s nostril. 

The Pleiades and Hyades star clusters are to the upper left of the Jovian Giant.

Photo Caption – Jupiter (NASA Photo)

Early this morning (12:43 a.m. CDT), Jupiter’s Great Red Spot is at the center of the planet in the southern hemisphere.

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

Mercury is emerging from bright sunlight.  It rises over forty minutes before daybreak. It is not easily visible this morning.

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 slides into brighter evening twilight, setting about fifty minutes after the sun.  It reaches solar conjunction November 18th and begins a slow climb into the eastern morning sky, west of the sun.  Its visibility begins during late January, 2024, with a Mercury conjunction on the 27th, followed by a Venus conjunction on February 22nd.

Chart Caption – 2023, September 11: Saturn is in the southeast with Skat and Lambda Aquarii (λ Aqr) after sundown.

Saturn rises before sunset and two hours after nightfall. The Ringed Wonder is nearly 25° up in the east.  It is not as bright as Venus or Jupiter, but it outshines most stars this evening.  It retrogrades in front of Aquarius, 9.1° to the upper right of Skat, the Aquarian’s leg, and 9.3° to the right of Lambda Aquarii (λ Aqr).  Use a binocular to find the stars, especially from urban and suburban settings.  They are not in the same field of view with the planet.

Look for Fomalhaut, the mouth of the Southern Fish, below Saturn and near the horizon.

Saturn is in the south around midnight as Earth’s rotation seems to make the sky spin westward.  It disappears into the haze and filtering effects of the atmosphere near the horizon during morning twilight. 

Jupiter rises in the eastern sky over two hours after sundown.  By tomorrow morning it is high in the south-southwest during morning twilight against Aries.


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