April 10, 2023: Brilliant Evening Star Venus passes the Pleaides star cluster in a pretty conjunction. Venus joins Mercury and Mars in the evening sky, while Saturn and the gibbous moon are visible before sunup.
by Jeffrey L. Hunt
Chicago, Illinois: Sunrise, 6:19 a.m. CDT; Sunset, 7:26 p.m. CDT. Check local sources for sunrise and sunset times for your location. Times are calculated by the U.S. Naval Observatory’s MICA computer program.
Summaries of Current Sky Events
Here is today’s planet forecast:
This morning the bright moon, 81% illuminated, is low in the south-southwest, 2.0° to the left of Antares, the brightest star in Scorpius at one hour before sunrise. To see the star with the bright moonlight, block the moon with your hand as you would shade your eyes from the sun. The moon continues its eastward hop. Find it farther toward the eastern horizon tomorrow morning.
Saturn is visible at this hour, but it rises higher and appears through the blush of morning twilight in the east-southeast as daybreak approaches. Fifteen minutes later, the Ringed Wonder is nearly 10° above the horizon. It rises earlier each morning compared to sunrise, appearing higher in the sky.
Jupiter is at conjunction tomorrow on the far side of the sun. It moves into the morning sky, emerging from bright morning twilight next month.
Venus and Mercury are in the western evening sky at nightfall. Brilliant Venus stands nearly 30° up in the west at 45 minutes after the sun disappears below the horizon. It is brightest starlike body in the sky and its visual intensity competes with the lights on low-flying airplanes.
Tonight and tomorrow evening, Venus passes the Pleiades. It is 2.6° to the lower left of Alcyone, the brightest star in the cluster, and 12.4° to the lower right of Aldebaran, Taurus’ brightest star.
Use a binocular to spot the planet and the star cluster in the same field of view. With or without a binocular this is a wonderous scene, especially as the sky darkens further. Venus sets 205 minutes after sunset with the end of twilight occurring 90 minutes earlier, though do not wait until the planet and the star cluster are too low in the sky. The next visible Venus-Pleiades conjunction occurs July 5, 2025.
The Pleiades and other similar so-called open clusters or galactic clusters are used as benchmarks for the ages of stars. The cluster has many blue stars, indicating a younger age. That is, bright blue stars tend to consume their nuclear fuels quicker than the sun and morph into their next stellar stages as red giants and red supergiants.
Look for Sirius, the night’s brightest star in the south-southwest. It is slightly lower in the sky than Venus and less than 60° from the Evening Star.
Mercury’s largest separation from the sun, known as the greatest elongation, occurs tomorrow evening. Find it 10.0° up in the west-northwest and nearly 20° to the lower right of Venus.
Mercury is making its best appearance of the year. This evening it sets 105 minutes after sundown, so look for it early.
At arm’s length, hold a fist vertically with the pinky finger at the horizon. Mercury appears near the thumb knuckle. Venus is two stacked fists to the upper left of the speedy planet.
Mars, less than 40° to the upper left of Venus, marches eastward against Gemini’s distant stars. It is less than 15° to the lower right of Castor, one of the Twins. Pollux, the other Twin, is 4.5° to the left of Castor.
As evening twilight ends, Venus is about 20° above the western horizon, while Mars is over 50° above the west-southwest horizon. The accompanying chart shows Gemini’s dimmer stars that are visible away from the perpetual glow of outdoor light. In urban and suburban settings, Castor, Pollux, and Alhena are visible. The pattern resembles two stick figures.
Use a binocular to spot the Red Planet, 1.9° to the lower right of Mebsuta – meaning “the outstretched paw of the lion.” During the next few evenings, watch Mars appear to pass this star.
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