January 28, 2023: After sundown, the slightly gibbous moon is near Uranus. Mercury is low in the southeastern sky before sunrise.
by Jeffrey L. Hunt
Chicago, Illinois: Sunrise, 7:07 a.m. CST; Sunset, 5:01 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: 7:45 UT, 17:40 UT; Jan. 29, 3:36 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.
The moon is at First Quarter phase – half illuminated – at 9:19 a.m. CST.
Here is today’s planet forecast:
Morning Sky
Mercury is nearing greatest elongation from the sun. This occurs tomorrow evening when the sun is below the horizon from Chicago. During the next few mornings, the planet rises over 90 minutes before sunup and 45 minutes later it is nearly 7° up in the southeast, to the lower left of Antares.
Evening Sky
After sunset, the slightly gibbous moon, 54% illuminated, is two-thirds of the way up in the sky in the south-southwest. Through a binocular the lunar orb is 1.7° to the lower right of Uranus. The planet is visible in a dark location without optical help, although it is at the limit of dim objects that humans can see without the brightness increase made by a binocular or telescope. (For astronomy, the most important feature of an optical device is to make the celestial object look brighter than it does to the unaided eye.)
Uranus is in a non-descript starfield in Aries, over 12° to the left of Hamal, the constellation’s brightest star, although it is about the same brightness as the brightest stars in the Big Dipper.
Uranus’ sidereal backdrop is made of stars that are not visible from urban and suburban settings without an optical assist, for they are washed out by the perpetual blaze of outdoor lighting. The starfield consists of Pi Arietis (π Ari on the chart), Omicron Arietis (ο Ari), and Sigma Arietis (σ Ari). The three stars are distinctly blue white, while starlike Uranus is aquamarine. The globe of the planet begins to appear through a telescope.
Along with the moon, four bright planets are in the sky after sundown. Brilliant Venus is over 10° above the west-southwest horizon at 45 minutes after the sun sets. After the moon, it is the next brightest celestial sight tonight. It is stepping eastward toward Jupiter, over 33° to the upper left, and away from Saturn, 6.9° to the lower right.
Saturn is about 6° above the horizon and continuing to slip into bright evening twilight. In a few evenings, it is immersed in the bright blush of evening’s afterglow, only visible with an optical assist. During mid-February, it passes behind the sun, then appears in the morning sky during late March. The precise evening of the planet’s disappearance is difficult to predict, because of local sky conditions. We are at the end of its appearance for this cycle of visibility.
Bright Jupiter is slowly moving eastward in a dim Pisces starfield, nearing the border with Cetus. Venus passes by on the evening of March 1st. Beginning February 20th, Venus is within 10° of the Jovian Giant, closing in each evening.
Farther eastward, Mars is above a bright congregation of stars that shine during the winter months. It is moving eastward in front of Taurus. It passes Aldebaran – the constellation’s brightest star – in two evenings. The wide conjunction is the third of a triple conjunction series.
Capella – meaning “the little she-goat” – is to the upper left of Mars. The star is part of Auriga – the Charioteer.
The Twins, Castor and Pollux, are about a third of the way up in the east-northeast and below Capella.
Famous Orion is below Mars and Taurus. The constellation is easy to recognize. Even in this moonlight, the belt – three stars of nearly equal brightness in a short line – is easy to locate. Bright Betelgeuse – a shoulder – and Rigel, Orion’s knee, shine brightly.
Betelgeuse, Procyon, and Sirius make the Winter Triangle, an informal name for this stellar trio because it appears in this season’s evening sky. For those wanting to find Sirius at its heliacal rising during August at the mid-northern latitudes, this is nearly the orientation of the three stars during brighter twilight on those mornings. Notice the scale of the triangle, especially from Betelgeuse to Procyon.
The triangle is nearly equilateral and its shape can be traced in the sky on those summer mornings when looking for the first appearance of the Dog Star.
At 9:36 p.m. CST, Jupiter’s Great Red Spot is in the center of the planet, but from Chicago, Jupiter is near the horizon. For sky watchers in the American West, the planet is higher in the sky and perhaps in clearer air. The window to see the spot during this Jupiter apparition is quickly closing.
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