2023, January 19: Morning Mercury, Thin Moon, Venus Chases Saturn


January 19, 2023:  A razor-thin lunar crescent appears near Mercury before sunrise.  Venus continues to close in on Saturn leading up to their conjunction in three nights.

Photo Caption – 2022, January 29: Mars and the crescent moon in the southeast before sunrise.


by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 7:14 a.m. CST; Sunset, 4:49 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: 5:16 UT, 15:12 UT; Jan. 20, 1:08 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

Chart Caption -2023, January 19: Mercury and the crescent moon are in the southeastern sky before daybreak.

Forty-five minutes before sunrise, a razor-thin moon, 8% illuminated, is less than 10° up in the southeast.  Use a binocular to examine the crescent and earthshine on the night portion.  This effect is from sunlight reflected from Earth’s features.

Speedy Mercury is about the same altitude – height above the horizon – as the crescent in the east-southeast, nearly 14° to the moon’s left.  It is the brightest star in this region of the sky and it continues to brighten and rise earlier for the next several mornings. It rises at least 90 minutes before sunup until the 27th

Mercury’s retrograde ended yesterday and it is moving eastward against the starry background.  The planet reaches its largest separation from the sun, known as the greatest elongation, on the 29th. On this morning, it rises 88 minutes before sunup.

This is the last morning to see the moon during this lunar cycle, known as a lunation.  Cycle 1238 begins at the New moon on the 21st at 2:53 p.m. CST.

Evening Sky

Chart Caption – 2023, January 19: Venus closes in on Saturn after sundown. Jupiter is higher in the sky.

Forty-five minutes after sundown, brilliant Venus is about 10° above the west-southwest horizon and 3.3° to the lower right of Saturn.  In three nights, the Evening Star passes the Ringed Wonder in a close conjunction. The next easily observed Venus-Saturn conjunction occurs two years from tonight!

Jupiter is about halfway up in the south-southwest, over 40° to the upper left of Venus.  The Jovian Giant is moving slowly eastward in front of Pisces’ dim stars.  This planet moves eastward about half Venus’ speed.  Venus catches Jupiter on March 1st.  From February 20th to March 11th, the two bright planets are within 10° when Venus approaches Jupiter, passes it, and then moves farther eastward from the slower-moving planet.

Chart Caption – 2023, January 19: After sunset, Mars is in the eastern sky, to the upper left of Aldebaran and to the right of Capella.

At this hour, Mars is over halfway up in the east-southeast, to the upper left of Aldebaran, the brightest star in Taurus, and to the right of Capella.  After its retrograde ended a week ago, the planet is slowly marching eastward.

Chart Caption – 2023, January 19: During the evening, Taurus makes the stellar backdrop for Mars.

As the sky darkens further and Taurus’ dimmer stars appear, look for Mars’ location compared to the constellation. Use a binocular to spot the Hyades star cluster, the Pleiades cluster, and Zeta Tauri, the Bull’s southern horn.

Chart Caption – 2023, January 19: Through a binocular Venus and Saturn are visible in front of eastern Capricornus.

Turn the binocular toward Venus and Saturn to see them against the starfield in eastern Capricornus. Both planets easily fit into the same field of view.  Venus is 1.3° to the lower right of Nashira.  Saturn is noticeably east of Deneb Algedi and 45 Capricorni (45 Cap on the chart).  The planet is 1.5° to the upper right of Deneb Algedi.

Photo Caption – This Hubble Space Telescope view of Jupiter, taken on June 27, 2019, reveals the giant planet’s trademark Great Red Spot, and a more intense color palette in the clouds swirling in Jupiter’s turbulent atmosphere than seen in previous years. The colors, and their changes, provide important clues to ongoing processes in Jupiter’s atmosphere.

At 7:08 p.m. CST, Jupiter’s Great Red Spot is center stage for sky watchers with telescopes. The planet is over 30° up in the southwest from Chicago.  Sky watchers farther westward see the planet higher in the sky.

At this time Europa is seen against the planet’s clouds. The large satellite moves back against the darkness of the night about the time the spot disappears from view a few minutes before 9:20 p.m. About that time, the moon’s shadow begins to cross the cloud tops.  From Chicago, the shadow is there until the planet sets.  From the Pacific Time Zone, the shadow leaves the planet before 9:30 p.m. PST when Jupiter is less than 10° above the horizon.



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