MUSCAT – This occurs when the sun is directly above the equator, resulting in nearly equal lengths of day and night across much of the world.

Astronomical calculations indicate that this year’s equinox will take place at 10:19 pm, Oman time.
In Muscat Governorate, the sun will rise tomorrow at 5:55 am, reach its highest point at 11:59 am, and set at 6:03 pm, making the day approximately 12 hours and 8 minutes long. The slight extra daylight is due to atmospheric refraction, which causes the sun to appear slightly earlier at sunrise and at sunset due to the bending of its rays through the atmosphere.

Enas bint Saif Al Mahrouqi, member of the Omani Society for Astronomy and Space, explained, “The exact day when night and day are perfectly equal, known as ‘Equilux’, will occur in Oman on Sunday, September 28, 2025. On this day, the sun will rise at 5:57 am and set at 5:57 pm, with a full 12 hours of daylight, depending on the region’s latitude.”

She added that the Earth’s 23.5-degree axial tilt and its 365.25-day orbit around the sun create the seasons and cause the equinoxes and solstices. During the autumnal equinox, the sun moves from the Northern Hemisphere, which includes Europe, Asia, North America, and the northern half of Africa, to the Southern Hemisphere, where spring begins.

Al Mahrouqi noted that on this day, the Arctic will witness its first sunset in six months, starting a long night lasting until the spring equinox, while the Antarctic will see its first sunrise after six months of darkness.

As autumn progresses in the Northern Hemisphere, daylight gradually shortens until the winter solstice on December 21, 2025, when the night reaches its longest duration.

The autumnal equinox, typically occurring between September 22 and 23, also marks the days when the sun rises exactly in the east (90 degrees) and sets in the west (270 degrees), enabling precise orientation. On the equator, noon shadows disappear on this day, a phenomenon known as ‘zero shadow day’.

Al Mahrouqi emphasised the educational value of observing these phenomena, suggesting students can use simple tools like sundials to track shadow movements and better understand seasonal changes. This hands-on approach links astronomy with earth sciences, enriching learning and research.
She concluded by saying: “The autumnal equinox is one of the four key astronomical events marking the start of seasons, alongside the vernal equinox and the summer and winter solstices. During equinoxes, day and night are roughly equal, while the solstices mark the longest day or night, shaped by Earth’s axial tilt and geographic location.”