September 22, 2022: Autumn begins in the northern hemisphere this evening. The moon is near the Sickle of Leo. Mars continues its eastward march through Taurus.
by Jeffrey L. Hunt
Chicago, Illinois: Sunrise, 6:38 a.m. CDT; Sunset, 6:48 p.m. CDT. Check local sources for sunrise and sunset times for your location.
The sun reaches the coordinates of the autumnal equinox (180°, 0° ecliptic coordinates) at 8:04 p.m. CDT. The sun’s rays are most-direct at the equator and until March 20, 2023, the sun shines more directly at the southern hemisphere.
The autumnal equinox is the time when the sun’s rays are directed toward the equator and it is a place in the sky. When the sun reaches those coordinates, we declare the beginning of autumn in the northern hemisphere.
The sun rises at the east cardinal point and sets at the west direction. Expect to see photos in social media and newscasts of the sun either rising or setting in the east-west concrete canyons of major cities during the next day or so.
Additionally, the equinoxes are the intersections of two coordinate systems. One is based on the celestial equator, an imaginary line above the earth’s equator in the sky. In this system, longitude is measured in hours, like time. Latitude is measure in degrees, like Earth’s lines of parallel, north and south of the equator.
The second system is framed on the plane of the solar system. It is tilted 23.5° to the celestial equator mirroring Earth’s tilt. The sun, moon, and planets seem to move on or near that imaginary line. Normally they move to the east – left on the chart above – compared to the starry background.
The sun’s apparent motion is a reflection of Earth’s yearly revolution, tilt, and daily rotation. For simplicity, it is easy to consider that Earth is stationary and the sun, moon, and planets are moving and that they are the same distance as the stars. In that way, these articles sometimes refer to the moon and planets being “in” a constellation. Rather, the stars form a distant background for the apparent motions of the sun, moon, and planets, that are a combination of the individual body’s motions and Earth’s movement.
The vernal equinox is the origin of both celestial systems and the autumnal equinox is halfway around the sky.
If you are a night owl or early riser, three bright planets – Mars, Jupiter, and Saturn – are strung across the sky about five hours before sunrise; that’s about 1:30 a.m. CDT in Chicago.
Here is today’s planet forecast:
Step outside an hour before daybreak. The thin crescent moon, 12% illuminated, is less than one-third of the way up in the east. It is over 10° above Regulus, Leo’s brightest star.
Regulus is the bottom of a backwards question mark that outlines the Lion’s head. The pattern is sometimes known as the “Sickle of Leo,” a farmer’s implement to cut crops. This scene seems as though the sickle is about to slice the moon.
Look for earthshine, reflected sunlight from Earth’s oceans, clouds, and land, that gently illuminates the lunar night.
Mars, marching eastward in Taurus, is between the Bull’s head, outlined by Aldebaran and the Hyades star cluster, and the horns, tipped by Elnath and Zeta Tauri. The planet’s morning-to-morning locations are easy to track.
Through a binocular, the planet appears to be approaching Iota Tauri (ι Tau on the chart). It passes the star tomorrow.
Farther westward, bright Jupiter is low in the west-southwest. Its retrograde continues as its opposition with the sun occurs in four days when Earth passes between the planet and the sun.
On opposition night, the planet rises at sunset and sets the next morning at sunrise.
Jupiter is the brightest star in the sky until Venus rises 42 minutes before sunrise, during brighter twilight. By 25 minutes before sunrise, the Morning Star is only 3° above the eastern horizon.
Venus and Jupiter are nearing their opposition on October 1. Jupiter sets as Venus rises. What is the last date that you see them in the sky simultaneously? They are bright enough to be seen near the horizon, if there’s a clear view in their directions. After the planet-to-planet opposition, Jupiter sets before Venus rises.
As darkness falls, bright Jupiter and Saturn are in the eastern sky. The Jovian Giant is low in the east, while Saturn appears in the southeast.
The Ringed Wonder continues its retrograde in eastern Capricornus, near Deneb Algedi and Nashira. Through a binocular Saturn widens the gap to Nashira and closes in on Iota Capricorni.
Mars follows Jupiter across the eastern horizon over three hours after sundown. As the night progresses the Red Planet appears higher in the east. Overnight, the three planets are again strung across the sky, Mars in the east; Jupiter, south; and Saturn, southwest.