2023, October 30: Moon-Pleiades Conjunction, Darkness and Daylight

October 30, 2023: Before sunrise, the bright gibbous moon appears with the Pleiades through a binocular.  Darkness exceeds daylight.

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

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by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 7:20 a.m. CDT; Sunset, 5:48 p.m. CDT.  Check local sources for sunrise and sunset times. Times are calculated by the US Naval Observatory’s MICA computer program.

Harvest
Harvest (Photo by Johannes)

Beginning tomorrow, darkness is longer than daylight.  This is not to be confused with the equinox that equally divides daylight and nighttime.  Daylight occurs when the sun is in the sky.  Its length varies during the year. Its length is simply calculated by subtracting the sunrise time from the sunset time.  By adding twelve hours to the sunset time makes the calculation easy.  In some circumstances, it is necessary to borrow and hour, convert it to sixty minutes, and add it to the sunset’s minutes column to complete the calculation. Today’s length is ten hours, twenty-eight minutes.

Nighttime is when the sun is not in the sky, about twelve hours at the equinox. Today, the length is thirteen hours, thirty-two minutes.  Subtract daylight’s length from twenty-four hours, borrowing an hour or 60 minutes to calculate the minutes value.  Nighttime is longer than daylight.

2021, May 12: Venus, the crescent moon, and Mercury are in the west-northwest after sunset.
2021, May 12: Venus, the crescent moon, and Mercury are in the west-northwest after sunset.

For the statement, “darkness is longer than daylight,” needs further explanation.  Nighttime has three phases, evening twilight when the western sky is illuminated after sunset, darkness, and morning twilight before the sun rises. 

These articles rely on the US Naval Observatory’s MICA computer program for the values related to this description.  It provides times for the beginning of morning twilight, sunrise, sunset, and end of evening twilight.  By calculating the length of twilight during a day and then subtracting this value for night’s length, darkness is determined.

Darkness is when the sky is as dark is it gets naturally.  The metaphors, such as “dark as midnight” and “darkest before the dawn” do not refer to nature.  At the end of evening twilight or beginning of morning twilight, the sky is as dark as midnight.

sunset over ocean
Sunset over the ocean

So, beginning tomorrow, darkness is longer than daylight until February 10, 2024, for 102 days at Chicago’s latitude.  Locations farther south have fewer days and those farther northward experience more days for this effect.

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

Here is today’s planet forecast:

Morning Sky

2023, October 30: Before sunrise, the moon and Pleiades appear in a binocular’s field of view.
Photo Caption – 2023, October 30: Before sunrise, the moon and Pleiades appear in a binocular’s field of view.

During morning twilight, the bright gibbous moon, 97% illuminated, is over 30° up in the western sky.  Through a binocular, the Pleiades star cluster, 3.5° above the lunar orb, and the moon appear in the same binocular field.  While easier to see than the dimmer planets, the moonlight can wash out dimmer stars. Once you find the scene, then move the binocular upward slightly so the moon leaves the field and the star cluster is below the center of the view.

The moon passes 1.6° south of the star cluster at 10:30 a.m. CDT, long after it sets across North America.

2023, October 30: Jupiter and the bright moon are in the western sky before daybreak.
Chart Caption – 2023, October 30: Jupiter and the bright moon are in the western sky before daybreak.

Bright Jupiter is about halfway from the western horizon to the gibbous moon. It is retrograding in front of Aries, 11.8° to the lower left of Hamal and 11.7° to the right of Menkar.  It appears to be passing between the two stars. Use a binocular to find Menkar.

Earth is between Jupiter and the sun in four mornings.  Because the Jovian Giant and the central star appear in opposite directions in the sky, Jupiter is said to be at opposition. Jupiter rises at sunset and sets at sunrise.  The planet is closest to Earth on these occasions that occur about every 400 days.

2023, October 30: During morning twilight, brilliant Venus is in the east-southeast with Leo.
Chart Caption – 2023, October 30: During morning twilight, brilliant Venus is in the east-southeast with Leo.

Farther eastward, brilliant Venus, rising at its maximum time interval before sunrise, is over 30° above the east-southeast horizon. It steps eastward in front of Leo, over 20° to the lower left of Regulus, Leo’s brightest star, and 11.9° to the lower right of Denebola, the tail.  Venus passes Denebola in a wide conjunction in a few mornings.

Evening Sky

Mercury and Mars set several minutes after sunset and they are not visible.

2023, October 30: An hour after sunset, Saturn is in the south-southeast near Deneb Algedi.
Chart Caption – 2023, October 30: An hour after sunset, Saturn is in the south-southeast near Deneb Algedi.

An hour after sundown, Saturn is over 30° above the south-southeast horizon.  It retrogrades in front of Aquarius, 6.7° to the left of Deneb Algedi, Aquarius’ tail.  Both fit into the same field of a binocular.  The planet’s retrograde ends November 4th.

2023, October 30: Two hours after sundown, Jupiter and the gibbous moon are in the eastern sky.
Chart Caption – 2023, October 30: Two hours after sundown, Jupiter and the gibbous moon are in the eastern sky.

Farther eastward at this hour, bright Jupiter is less than 10° up in the east-northeast. Two hours after sunset, the planet is nearly 20° up in the east and over 25° to the upper right of the gibbous moon, 94% illuminated.

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