Goodnight, (super) moon: Harvest moon the last 'super' show of the year

Supermoon fans have had quite a feast for the eyes lately, with four full moons since July getting the distinction.

But all that comes to an end this week, with the arrival of a rare harvest supermoon tonight.

Supermoon describes a full moon that occurs within 10% of its closest approach to Earth - about 226,000 miles. When that happens, the full moon can appear 14% larger and 30% brighter than one at its furthest distance from Earth.

Harvest moon is the name for the full moon that appears closest to the autumnal equinox, which occurred Saturday. The term has roots in American agricultural history, dating back to the time before plows and tractors came equipped with electrical lighting.

"If they needed to be out harvesting their crops, the moon would be nice and bright, so that if they needed to stay out past sunset, they could and still work on getting the crops in," said Michelle Nichols, director of public observing for the Adler Planetarium.

In the 1900s, it was immortalized in song with the tune "Shine on, Harvest Moon," co-written by Jack Norworth, better known for writing "Take Me Out to the Ballgame."

Nichols said the exact time of full moon is 4:57 a.m. Friday. However, it will appear full beginning about 6:31 p.m. Thursday in the Chicago area.

"It's not exactly at full moon time, but it's close," she said. "You can go out at moonrise on (Thursday) if you want to and see what will look like a full moon."

You can also view it Friday evening, when moonrise occurs about 6:55 p.m. With a relatively low angle in the sky, you will be able to experience an optical illusion that makes the moon huge near the horizon. The best way to view it is facing east in a location without a lot of trees and buildings in the way.

The next supermoons are expected on Sept. 17 and Oct. 17, 2024. The former will bring with it a partial lunar eclipse.