Watching the Skies: Astronomical fall arrives this week

GRAND RAPIDS, Mich. (WOOD) — Meteorological fall began a few weeks ago, but astronomical fall arrives this week. While meteorological fall is based on climatology, astronomical fall is based on the position of the sun.

The autumnal equinox is marked by the moment the sun crosses the celestial equator. In that moment, the earth is not tilted toward or away from the sun. This will happen around 9:30 a.m. on Tuesday.

“Equinox” translates to “equal night.” This implies that there would be exactly 12 hours daylight and 12 hours of nighttime on an equinox, but that isn’t exactly the case. On Tuesday, the sun will rise around 7:30 a.m. and set around 7:38 p.m. Our actual day of “equal night” will come a few days after the autumnal equinox.

Look for the sun to rise directly in the east and set directly in the west at the time of the equinox. After the equinox, the sunrises and sunsets will begin to take on more southerly component.

On the evenings of Wednesday, Thursday, Friday and Saturday, the moon and a pair of planets will light up the evening sky.

Look to the south at dusk to see the moon, Jupiter, and Saturn. The moon will obviously be the brightest, so once you’ve located the moon, look for Jupiter nearby. Jupiter is currently the fourth brightest celestial object, so it will also be easy to spot.

After identifying Jupiter, look for Saturn just to the left. If you have a telescope, you may be able to pick out Saturn’s rings and Jupiter’s major moons.

The moon will start to the right of Jupiter, then pass to the left of Saturn over the next four evenings.

Sam Tuene sent in this picture of the crescent moon and Venus early in the morning last week. Venus is still putting on a show in the east before sunrise.

The crescent moon and Venus early in the morning. (Couresy: Sam Tuene)