May 12, 2023: The moon is near Saturn in the southeast before sunrise. Sirius and Aldebaran are at their heliacal settings, their final appearances in the western sky after nightfall.
by Jeffrey L. Hunt
Chicago, Illinois: Sunrise, 5:34 a.m. CDT; Sunset, 8:01 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:
Morning Sky
This morning the slightly gibbous moon, 52% illuminated, is in the southeast during morning twilight. The Last Quarter phase occurs at 9:28 a.m. CDT, when the moon is low in the southwestern sky.
At forty-five minutes before daybreak, Saturn is over 20° above the southeastern horizon and over 15° to the left of the moon. Each morning it is slightly higher in the sky and easier to see. It is not as bright as Venus or Jupiter, but it is among the brightest stars in the sky this morning.
Jupiter rises over two hours after Saturn. By thirty minutes before sunrise, it is over 4° above the eastern horizon. From an observing location with an unobstructed, cloud free horizon, the planet is visible through a binocular. The sky is too bright to see it unassisted today.
Mercury is speeding into the morning sky, rising less than 25 minutes after Jupiter. It is heading toward a difficult-to-see appearance next month.
Evening Sky
At forty-five minutes after sundown, the bright stars that shine in the southern sky during winter are low in the west. Sirius, the night’s brightest star, is low in the west-southwest, bathed in the blush of evening twilight. It is slowly disappearing into sunlight. It reappears in the morning sky in the east-southeast around mid-August.
Similarly, Aldebaran is very low in the west-northwest. Dimmer than Sirius, a binocular might be necessary to see it less than 4° above the horizon.
Betelgeuse is over 10° above the west horizon. It disappears into evening twilight in about a week.
The final appearance of a bright star into bright twilight after sundown is known as the heliacal setting. Theoretical dates can be calculated, but are affected by local circumstances, such as cloudy evenings and terrain.
Venus is the showpiece of the evening sky. It stands in the western sky as night falls. Simply described, it is “that bright star in the west.” By far, it outshines all other starlike bodies in the night sky and rivals the lights on low flying airplanes.
The planet is stepping eastward in front of Gemini near Castor’s heel, Tejat Posterior, also known as Mu Geminorum (μ Gem on the chart). This evening it passes 3.6° to the upper right of the star.
Through a binocular, Venus appears close to the star cluster Messier 35 (M 35 on the chart). It is 4.0° above the stellar bundle.
Mars, marching eastward near Pollux, one of the Gemini Twins, is less than 20° to the upper left of Venus. The Red Planet is about 200 times dimmer than Venus. Compared to the nearby starfield, Mars is dimmer than Pollux, but brighter than Castor. The planet is visible as the stars shine through the dying fires of daylight.
Wait until the sky is darker. The accompanying chart shows Gemini at 90 minutes after sundown when the fainter stars are visible. The Twins look like two side-by-side stick figures, with Pollux and Castor dotting their heads.
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