2023, April 29: Celebrate Astronomy Day

April 29, 2023:  Today is Astronomy Day, a celebration of the universe.  Join an evening star party with a local astronomy club or science center.

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by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 5:50 a.m. CDT; Sunset, 7:47 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.

As April ends and a new month begins, daylight’s length increases to more than 14 hours at Chicago’s latitude.  The length of darkness, from the end of evening twilight to the beginning of twilight the next morning is only six hours, 30 minutes.

Today is Astronomy Day, founded by the Astronomical League, an umbrella organization for over 200 local astronomy amateur groups.  This is the 50^th anniversary of the first Astronomy Day.  Along with the League, the celebration is organized with other groups such as the Astronomical Society of the Pacific and The Planetary Society.

Attend a celebration of astronomy that includes telescope viewing, astronomy talks, and other exhibits, depending on the site.  Find your local astronomy group at the League’s web site. Many planetariums and science centers participate in the day’s events.

Here is today’s planet forecast:

Morning Sky

Saturn continues a slow climb into the east-southeastern sky before sunrise. Each morning it rises two minutes earlier compared to sunrise time.  This morning, rising 140 minutes before the sun, the Ringed Wonder is over 15° above the horizon.  It might be blocked by neighborhood buildings or trees.  Find a clear horizon looking toward it.

Jupiter follows Saturn into the morning sky.  Still rising in bright twilight, the Jovian Giant rises about two hours after Saturn and less than 30 minutes before daybreak.  It makes its first appearance next month.

During daytime in the Americas, nighttime farther eastward, the moon eclipses or occults the star Eta Leonis (η Leo) for sky watchers in India and Indonesia.

Evening Sky

Mercury is heading toward a morning appearance, but still setting after sundown.  The speedy planet follows the sun to the horizon nearly twenty minutes after the sun sets.

Venus is the showcase of the evening sky.  The brilliant Evening Star is over 30° above the western horizon after sunset.  It is easily described as “that bright star” in the west.  It sets over 3 hours, 30 minutes after the sun.

The brilliant planet is stepping eastward against the stars in eastern Taurus, 3.3° to the lower left of Elnath, the Bull’s northern horn, and 5.7° to the lower right of Zeta Tauri, the southern horn.  It passes Elnath tomorrow evening and treks between the horns on May 1^st.

The bright waxing moon, 70% illuminated, is high in the south, 5.0° to the upper left of Regulus, Leo’s brightest star. The bright moonlight whitewashes the sky, covering the dimmer stars. To see Regulus, block the moon with your hand or the edge of a building.

Mars, marching eastward in Gemini and 7.0° below Pollux, continues to fade in brightness.  The Red Planet is dimmer than Pollux, but brighter than Castor.  It passes Pollux in a wide conjunction on May 8^th.

It is easy to spot Venus, less than 30° to the lower right of Mars.  The gap in the sky between the two planets continues to close.  Venus moves eastward about twice Mars’ pace.  Venus appears to be running down Mars.  Venus steps into Gemini’s boundaries on May 7^th, over 20° from the dimmer world.

Tomorrow evening, the moon’s phase grows to nearly 80%, leading toward the Full phase on May 5^th.

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