2023, January 7: Mercury conjunction inferior, evening planet display continues

January 7, 2023: Mercury is in inferior conjunction between Earth and the Sun. Venus, Saturn, Jupiter and Mars continue their evening show after sunset.

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by Jeffrey L. Hunt

Chicago, IL: Sunrise, 7:18 a.m. CST; Sunset, 4:36 p.m. CST. Check local sources for sunrise and sunset times for your location. The times are calculated from the MICA computer program of the US Naval Observatory.

Sunrise is at its latest time. This continues throughout the 10^e. The duration of daylight increases slowly in January to ten hours at the end of the month.

Transit time of Jupiter’s Great Red Spot, when it is in the center of the planet in the southern hemisphere: 5:17 UT, 15:13 UT; January 8, 1:09 GMT. Convert the time to your time zone. In the US, subtract five hours for EST, six hours for CST, etc. Use a telescope to see the place. The hours are from Sky & Telescope magazine.

Mercury is in inferior conjunction, between Earth and the Sun, this morning at 6:57 a.m. CST. It speeds up in the morning sky, reaching its greatest separation from the sun towards the end of the month.

Mercury is not exactly between the Earth and the Sun, but it is 2.8° above central. Mercury’s orbit is inclined 7.0° to the Earth-Sun plane, known as the ecliptic.

As the fast-moving planet shifts from an evening sky to a morning view, it retrogrades. The planet moves faster than the Earth and passes it every 116 days. During the evening onset, Mercury is east of the sun, and west of the sun during its morning onset. To transition from evening to morning, the planet moves from east to west – or retrograde. This retrograde illusion occurs when Mercury and Venus pass in front of Earth.

Mercury stops retrograde on January 18 and reaches its greatest separation from the sun on January 30^e.

Here is today’s planetary forecast:

morning sky

The bright moon dominates the morning sky, seemingly whitening the view of the darker stars. One hour before sunrise, the lunar orb is nearly 20° above the west-northwest horizon. It is 2.7° lower left of Pollux and 6.2° lower left of Castor. The stars are the Gemini twins.

It is likely that the moon’s brightness overwhelms nearby stars. To see them, block the moon with your hand as you would to shield your eyes from the sun’s glare.

Each morning the moon is higher in the western sky and it begins to show its gibbous phase over the next few mornings.

evening sky

Forty-five minutes after sunset, the bright moon, 99% illuminated, is on the east-northeast horizon, casting its light across the sky.

At this time, Mars is at 40° east. Even brighter than all the stars in this part of the sky, the red planet quickly darkens as Earth moves away.

Mars retrograde illusion ends in five nights when the planet resumes its normal eastward motion. Tonight it is 8.5° above left of Aldebaran, the brightest star in Taurus.

Mars passes Aldebaran for the third time in a series of triple conjunctions on January 30^e.

Farther west, bright Venus is low in the southwest, less than 10° in the sky. Find a clear horizon to see it. It closes on January 22^n/a conjunction with Saturn. Tonight, the separation between the planets is 17.0°. The separation decreases by about 1° from evening to evening.

After conjunction with Saturn, Venus moves towards Jupiter, passing it on March 1^st. For several days before and after the conjunction, the two planets are close together in the sky. Their gathering is a spectacular sight to behold. The gap between Venus and Jupiter is 56.0° tonight, a sizable separation to close over the next few weeks.

For skywatchers with telescopes, the Great Red Spot is at the center of Jupiter in the Southern Hemisphere at 7:09 p.m. CST. From Chicago, the Jovian Giant is nearly 40° southwest. The long-lasting storm is visible for about an hour before and after it emerges into center stage, as Jupiter’s rapid rotation brings it into view and then fades it away.

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