Earth’s bi-annual balancing act will take place Monday, Sept. 22, at 2:19 p.m. The autumn equinox ushers in the astronomical first day of fall with equal hours of daylight nearly all around the world. Earth’s 23.4-degree tilt is the reason for our seasons. As Earth travels in its orbit, its axis leans towards or away from the sun. Twice a year, neither pole points towards the sun. In Sept., this marks the transition from summer to autumn in the Northern Hemisphere and from winter to spring in the Southern Hemisphere. From now until Dec. 21, daylight hours will continue growing shorter.

A skygazing delight will be Saturn at opposition on Sept. 21. A planet in opposition lines up directly opposite the sun in relation to Earth. On this evening, Saturn will gleam at its brightest in 2025 and will be visible from sunset to sunrise. For those observing with telescopes, Saturn’s rings will still be extremely close to edge-on. As part of Saturn’s fifteen-year ring cycle, Earth just recently experienced the phenomenon known as “crossing the ring plane.” Earth’s view of Saturn has changed from the Northern to the Southern Hemisphere for the first time in fifteen years.

Another phenomenon is the Seeliger effect. The German astronomer first noticed a surge in the ring’s brightness just before and after opposition. Briefly, the rings temporarily outshine the planet.