2024, October 7:  Moon-Antares Conjunction

October 7, 2024: The moon appears near the star Antares after sundown, a Moon-Antares conjunction.  During the night Venus, Saturn, Jupiter, and Mars are visible.

2019, January 31: The waning crescent moon is 2 degrees from Venus this morning with Jupiter 8.5 degrees to the upper right of Venus.
Photo Caption – 2019, January 31: The waning crescent moon is 2 degrees from Venus this morning with Jupiter 8.5 degrees to the upper right of Venus.

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by Jeffrey L. Hunt

Chicago, Illinois: Sunrise, 6:55 a.m. CDT; Sunset, 6:21 p.m. CDT.  Check local sources for sunrise and sunset times. Times are calculated by the US Naval Observatory’s MICA computer program.

Nighttime Planets

Four bright planets, Venus, Saturn, and Mars are visible during the night. (See yesterday’s article for details.)  Mercury, setting less than 15 minutes after the sun is slowly moving into the evening sky, but it is hidden in bright evening twilight.

Venus clouds from the Hubble Space Telescope. The planet shows phases. (NASA photo)
Chart Caption – Venus clouds from the Hubble Space Telescope. The planet shows phases. (NASA photo)

Venus shines through the colorful hues of evening twilight in the west-southwest at 40 minutes after sunset.  This evening the crescent moon is nearby.  More below.

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

Saturn, considerably dimmer than the Evening Star, is about 20° up in the east-southeast during the early evening.  As the calendar day ends, the Ringed Wonder is in the southern sky and bright Jupiter is in the east.  Mars rises about two hours after Jupiter.  By morning twilight, they are high in the southern sky.

Here is today’s sky watching highlight:

Moon-Antares Conjunction

2024, October 6-7: At 40 minutes after sunset, the moon is in the southwestern sky with Scorpius, while brilliant Venus is low in the west-southwest.
Chart Caption – 2024, October 6-7: At 40 minutes after sunset, the moon is in the southwestern sky with Scorpius, while brilliant Venus is low in the west-southwest.

After sundown, locate the crescent moon, 23% illuminated, low in the southwest and to Venus’ upper left.  This evening a Moon-Antares conjunction occurs.  The moon occults the star, but this occurs during daylight in the regions where it might be visible.

Look for earthshine on the moon, an effect from sunlight reflected from Earth’s features that gently lights up the lunar night.

2024, October 7: Through a binocular, the moon and Antares are visible together. The star cluster Messier 4 (M4) is to the star’s lower right.
Chart Caption – 2024, October 7: Through a binocular, the moon and Antares are visible together. The star cluster Messier 4 (M4) is to the star’s lower right.

Use a binocular to see the moon and earthshine with Antares and the nearby starfield.  Notice the star’s rusty color, determined by its temperature.  Antares, meaning “the rival of Mars,” is 2.4° to the right of the crescent.

In celestial artwork, Antares marks the heart of the Scorpion.  This is implied by the star Al-Niyat and the star Tau Scorpii (τ Sco on the chart), referred to as “the arteries.”

The H-R Diagram.
Chart Caption – The Hertzsprung-Russel Diagram is a chart to compare stellar properties. (Credit: European Space Agency)

Antares, the 11th brightest star for sky watchers at the mid-northern latitudes, shines with a brightness of over 9,000 suns from a distance of over 6000 light years.  It is thought to be over 300 times the sun’s diameter, a supergiant type star.

When stars near the end of their lives, the hydrogen nuclear fuel is exhausted.  To fuse other atomic nuclei, such as helium, the core collapses and heats up.  This outward rushing of heat inflates the outer stellar layers and cools them, turning them reddish.  Orion’s Betelgeuse is at a similar stage.

When supergiants cannot reach further rounds of core temperature increases, their outer shells are blasted into space in what are known as supernovae.

Look for Star Cluster

Globular clusters are inherently beautiful objects, but the subject of this NASA/ESA Hubble Space Telescope image, Messier 3, is commonly acknowledged to be one of the most beautiful of them all. (NASA/ESA Photo)
Photo Caption -Photo Caption – Globular clusters are inherently beautiful objects, but the subject of this NASA/ESA Hubble Space Telescope image, Messier 3, is commonly acknowledged to be one of the most beautiful of them all. (NASA/ESA Photo)

Additionally, a globular star cluster, catalogued as Messier 4 – M4 on the chart, is to Antares’ lower right.  These stellar bundles contain thousands of stars that are packed so tightly that they seem to be touching.  Unlike the galactic clusters, such as the Pleiades, globular clusters revolve around the center of the galaxy outside the plane, The clusters can be seen in any direction in the sky, although they are concentrated toward the galactic core behind Sagittarius’ stars.

Through a binocular, M4 resembles a tiny cotton ball.  A telescope begins to resolve individual stars in the cluster’s outskirts.

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