2023, October 29: Jupiter-Hunter’s Moon Conjunction

Jupiter, Saturn, Moon, October 22, 2020
Photo Caption – 2020, October 22: The nearly first quarter moon, overexposed in the image above, makes a nice triangle with Jupiter and Saturn. The planets are 5.9° apart. The moon is 4.4° to the lower left of Jupiter and 4.2° to the lower right of Saturn.


by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 7:19 a.m. CDT; Sunset, 5:49 p.m. CDT.  Check local sources for sunrise and sunset times. Times are calculated by the US Naval Observatory’s MICA computer program.

Photo Caption – 2022, February 2: Sunrise

Today daylight’s length is ten hours, thirty minutes at Chicago’s latitude.  It decreases approximately one to two minutes each day.  In comparison, the sun is in the sky forty-minutes longer at Miami, Florida’s latitude.

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, October 29: During the early morning hours, Jupiter and the moon are close together.

At the beginning of the new calendar day, the moon is passing close to Jupiter in the southern sky.  They are closest at 1:02 a.m. CDT, with the moon 2.6° to the upper right of the Jovian Giant. The bright Hunter’s Moon is next to bright Jupiter.

Chart Caption – The Celestial Sphere. (Image Courtesy of the Lunar and Planetary Institute)

Other writers may refer to a different time and distance.  Two different coordinate systems are used between sky watchers.  Some use the equatorial coordinates.  The celestial equator is an imaginary circle directly above Earth’s equator.  In this system, longitude is named right ascension and it is measured in hours, like a twenty-four-hour clock. A conjunction occurs when Jupiter and the moon have the same right ascension or equatorial longitude.

The Naval Observatory’s MICA computer program uses the equatorial system and predicts a Jupiter-Moon conjunction at 3:14 a.m. CDT and a separation of 3.1°.  This is the data some writers may use to describe this conjunction.

This writer uses the coordinate system based on the ecliptic, the solar system’s plane.  This is the location where the sun, moon, and planets appear to move against the famous zodiacal constellations, such as Aries, Taurus, Gemini, and the like.  Depending on how they are counted, the major solar system bodies can appear in front of at least fifteen constellations, the famous dozen, plus Ophiuchus, Orion, and Cetus.

In this system, the ecliptic is tilted 23.5° compared to the equator.  The easiest way to observe this tilt is to note the different rising points of the seasonal sun, toward the east-northeast during summer and east-southeast during winter.  Here conjunctions occur when the celestial bodies have the same ecliptic or celestial longitude.  Usually, these conjunctions occur when the two bodies are closest.

When conjunctions of the planets and moon are within about one degree, the equatorial conjunction information and ecliptic predictions are nearly the same.  When farther away, such as this morning, the times and separations can be hours apart.

It should be noted, both times and separations are accurate.  They specify conjunctions in the relative coordinate systems.

Chart Caption – 2023, October 29: During morning twilight, the bright moon and Jupiter are in the western sky.

Likely, only sky watchers, night owls, and Saturday-night revelers will note this early-morning conjunction.  For others look for them low in the western sky during morning twilight.  An hour before sunrise, the lunar orb is nearly 20° up in the west. The gap to Jupiter widens to 3.4°, still relatively close.

Chart Caption – 2023, October 29: Before daybreak, brilliant Venus is in the east-southeast.

Farther eastward, the brilliant Morning Star is about 30° up in the east-southeast. It steps eastward in front of Leo, nearly 20° to the lower left of Regulus, the Lion’s brightest star, and over 12° to the right of Denebola, the tail.  The pattern’s dimmer stars are washed out by the bright moonlight.

On November 1st, Venus passes Denebola in a wide conjunction.  Two mornings later, the planet moves into Virgo.

Through November 6th, Venus rises at its maximum rising time interval compared to sunrise, four minutes shy of four hours.  Then it begins to rise later compared to sunrise.  By the end of November, Venus loses thirteen minutes of rising time compared to this maximum rising time interval.

Evening Sky

Mercury and Mars are not visible.  Mercury is moving into the evening sky while Mars is heading toward its solar conjunction.  Mercury sets fourteen minutes after the sun and Mars follows four minutes later.

Chart Caption – 2023, October 29: An hour after sundown, Jupiter and the moon are in the eastern sky.

An hour after sunset, the bright gibbous moon, 88% illuminated, is about 5° above the east-northeast horizon.  It is 11.1° to the lower left of bright Jupiter.  The Jupiter-Moon gap is considerably wider than this morning, whether at its closest point or during morning twilight.

Chart Caption – 2023, October 29: An hour after sundown, Saturn and the star Fomalhaut is in the south-southeast.

At this hour, Saturn, noticeably dimmer than Jupiter, is over 30° up in the south-southeast.  It is retrograding in front of Aquarius, but the fainter starry background is difficult to see in this moonlight. The star Fomalhaut is about 20° to the lower left of Saturn.

Chart Caption – 2023, October 29: Three hours after sunset, Uranus and the moon are in the same binocular field of view.

When the moon is higher in the sky, Uranus might be visible through a binocular, 2.4° to the lower right of the lunar orb.  This is a challenging observation because of the moon’s glare.  While four stars in Aries, 63, Delta (δ Ari on the chart), Zeta (ζ Ari) , and Tau (τ Ari) are on the accompanying chart, the moonlight might overwhelm them as well.  To see the planet without the moon, shift the binocular slightly to the right so that the moon is out of the field of view. Take a look.  It should be noted that the bright moon viewed through a binocular may create a temporary after image in your vision, like that from a photo flash.



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