2023, January 24: Morning’s Mercury, Evening Planet Collection

January 24, 2023: Before sunrise, Mercury is visible in the southeastern sky.  After sundown, a collection of planets – Venus, Jupiter, and Saturn – appears with the moon.

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by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 7:10 a.m. CST; Sunset, 4:56 p.m. CST.  Check local sources for sunrise and sunset times for your location.  Times are calculated from the U.S. Naval Observatory’s MICA computer program.

Jupiter’s Great Red Spot’s transit times, when it is in the center of the planet in the southern hemisphere: 4:26 UT, 14:22 UT; Jan 25, 0:18 UT. Convert the time to your time zone. In the US, subtract five hours for EST, six hours for CST, and so on.  Use a telescope to see the spot.  Times are from Sky & Telescope magazine.

Here is today’s planet forecast:

Morning Sky

A week before its largest separation from the sun – known as the greatest elongation – Mercury is visible in the southeastern sky at forty-five minutes before sunup.  From a place with a clear view to the southeast, use a binocular to initially locate the planet, about 7° above the horizon.  While it is low in the sky, Mercury is brighter than reddish Antares that is nearly 20° up in the south-southeast and Altair that is nearly the same altitude as Antares and in the east.

The planet rises over 90 minutes before sunup, near its maximum rising interval before the sun crosses the horizon.

Evening Sky

In the western sky after sundown, a pretty menagerie of the moon and planets is visible.  Two evenings after its conjunction with Saturn, Venus is over 10° up in the west-southwest and 2.4° to the upper left of the dimmer Ringed Wonder.

The gap between Venus and Saturn continues to grow over 1° each evening. Venus moves into Aquarius tonight.  The stellar background is rather dim and its stars are not visible at this level of twilight and for many sky watchers in urban and suburban settings after the sky is fully dark naturally.

Saturn is slowly slipping into twilight.  In about a week, it disappears into the sun’s glare.

The crescent moon, 14% illuminated, is about one-third of the way up in the southwest, about halfway from Venus to Jupiter, the bright star to the crescent’s upper left.

The lunar crescent is showing earthshine – reflected sunlight from Earth’s features that gently illuminates the lunar night. A binocular helps with the view of the effect and a tripod mounted camera with an exposure of a second or more can capture earthshine.

Jupiter is nearly halfway up in the southwest.  It is slowly moving eastward in Pisces and nearing the Cetus border.  The Jovian Giant crosses into that constellation on February 5^th.

Venus is stepping quickly toward Jupiter, catching it on March 1^st.  This evening the gap is over 37°.

At this hour Mars is farther eastward, about halfway up in the east-southeast, to the upper left of Aldebaran. When the sky is darker, Taurus’ dimmer stars appear to make the celestial background.  The Red Planet is 8.3° to the upper left of the constellation’s bright star, Aldebaran.

On the 30^th, Mars has a wide conjunction (8.0°) with Aldebaran, the third of a triple conjunction series.  The Red Planet is marching eastward, picking up the cadence each night after its retrograde ended on the 12^th.

At 6:18 p.m. CST, the Great Red Spot is visible in the center of the planet in the southern hemisphere.  At this hour the planet is less than 40° up in the southwest.  For sky watchers with telescopes, the spot is in the clouds and two satellites appear near the Jovian Giant. Callisto is north of the planet and partly obscured by the solar system’s largest world.  Io is to the west of the planet and moving through its orbit that carries it behind the planet .  By 6:55 p.m. Callisto fully reappears. At 7:11 p.m. Io disappears behind Jupiter.  Around 8:25 p.m. the Red Spot disappears to the night side of the planet from Jupiter’s rapid rotation. By 9:25 p.m., Io reappears, but the planet is only a few degrees above the western horizon, setting about 30 minutes later.

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