2025, May 12: Final Performances – Procyon, Gemini Twins, Capella

May 12, 2025: Procyon, Gemini Twins – Castor and Pollux – and Capella make their final showings for the season.

by Jeffrey L. Hunt

Chicago, Illinois: Sunrise, 5:33 a.m. CDT; Sunset, 8:01 p.m. CDT.  Check local sources for sunrise and sunset times. Times are calculated by the US Naval Observatory’s MICA computer program.

Local Sunsets

Spectacular Desert Sunsets
Photo Caption – Spectacular Desert Sunsets

Sunset occurs after 8 p.m. Central Time in Chicago.  For locations farther westward in their time zones, sunset can be nearly an hour later.  For example, in North Platte, Nebraska, at the far western edge of the Central Time Zone, sunset occurs today at 8:51 p.m.  In comparison, the sun sets at Ogallala, Nebraska, about 50 miles west of North Platte and near the eastern edge of the Mountain Time Zone, at 7:55 p.m., only four minutes later than North Platte, but a time zone later.

Bright Flower Moon

The Full moon occurs today at 11:56 a.m. Central Time while it is below the horizon in the Americas.  The moon is still nearly full tonight and can still be named the Flower moon, the seasonal moniker for the second bright moon of the spring season.

Winter Stars Depart into Evening Twilight

Venus shines in Taurus, April 13, 2020
2020, April 13: Venus shines brightly this evening, 9.8° to the upper left of Aldebaran, the brightest star in Taurus.

For many sky watchers, Sirius, Orion’s Rigel, and Taurus’ Aldebaran, three bright stars that shine prominently during the winter season, have disappeared into bright evening twilight.  Betelgeuse, Orion’s shoulder departs the sky during the next week.  Tonight, at an hour after sundown, it is about 10° above the western horizon.

Look for bright Jupiter, less than 15° up in the west-northwest.  Use a binocular to spot it 2.3° to the right of Zeta Tauri, the Bull’s southern horn.  Elnath, the brighter northern point, is 5.7° to Jupiter’s upper right.  Notice that Jupiter is nearly between them.  The Jovian Giant continues to ramble eastward, passing between the horns in three evenings.  In celestial artwork, this is a precarious place.

Winter’s Second Wave

Procyon, Pollux, Castor, and Capella in the western sky after sundown, May 12, 2025
Chart Caption – 2025, May 12: Procyon, Pollux, Castor, and Capella are in the western sky after nightfall.

Four bright stars are above the first wave of departing winter stars. The final evening appearance, depending on latitude and the local weather, is known as the heliacal setting.  When the stars reappear in the eastern sky before sunrise, this is termed the heliacal rising.

Two stars of nearly equal brightness – Castor and Pollux – are about 45° above the west horizon.  At this season, Gemini, appearing as side-by-side stick figures, stands upright in the western sky.

Procyon, known as the Little Dog Star, is less than 30° above the west-southwest horizon and over 20° to Pollux’s lower left.

Capella, meaning “the little she-goat,” is less than 30° up in the northwest and about the same distance to Castor’s lower right.

Procyon disappears into western evening twilight around June 10th, reappearing at the helical rising around August 6th.

Castor and Pollux slide into western twilight during early July. Castor reappears around July 15th, followed by Pollux about a week later.

Capella is a special case because of its more northerly location.  Like Arcturus and Vega, Capella can appear in the eastern sky before sunup and in the western sky after sunset on the same calendar day.  This begins near month’s end when the star shines from about 5° above the north-northeast horizon at 45 minutes before sunrise and it is visible over 15° up in the northwest at an hour after sundown.  It finally disappears from the evening sky about a week after the summer solstice.  On that morning, during morning’s early light, the star is about 20° up in the northeast.

Watch Procyon, Pollux, Castor, and Capella disappear into evening twilight during the next several weeks.

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