Sunday 22 / September / 2024
Muscat: The autumnal equinox has officially begun in the Sultanate of Oman, marking the astronomical start of the autumn season. This significant event occurred today at 4:43 PM (MCT), signaling the moment when the sun crosses the celestial equator, resulting in nearly equal day and night across the globe.
Hawa bint Abdullah Al Balushi, a member of the Oman Astronomical Society, explained the phenomenon: “On the day of the autumnal equinox, the sun rises directly over the equator. In Muscat, the sun rose at 5:55 AM, reached its zenith at 11:59 AM, and will set at 6:03 PM, giving us approximately 12 hours and 8 minutes of daylight.”
Al Balushi also noted that the exact day when night and day are equal varies slightly by location. In Oman, this will occur on Saturday, September 28, with the sun rising and setting at 5:57 AM and PM respectively, resulting in exactly 12 hours of daylight.
She further explained that the Earth's rotation on its axis and its orbit around the sun are responsible for the changing seasons. The tilt of Earth's axis, at 23.5 degrees, causes variations in day length and the occurrence of solstices and equinoxes. This tilt is also the reason for longer summer days and shorter winter days.
The equinox typically falls on September 20, 21, or 22 due to slight differences between the calendar year and the tropical year, which measures the Earth's orbit around the sun. Adjustments, such as leap years, help realign the calendar with these natural cycles.
Al Balushi highlighted that on the day of the equinox, the sun is perfectly aligned with the equator, moving from the southern hemisphere—where countries like Australia and parts of South America and Africa are located—to the northern hemisphere, which includes Europe, Asia, North America, and the North Pole. This marks the start of autumn in the north and spring in the south.
She also pointed out an interesting observation: on this day, the sun rises at exactly 90 degrees east and sets at precisely 270 degrees west, providing a unique opportunity to accurately determine the directions of east and west.
In polar regions, the equinox has additional significance. At the North Pole, the sun rises for the first time in six months, heralding a day that will last half a year, while at the South Pole, the sun sets for a six-month-long night.
Looking ahead, Al Balushi mentioned that the autumn season will last 89 days, 20 hours, and 37 minutes, leading up to the winter solstice on Saturday, December 21. During this time, nights will gradually lengthen until the solstice, the shortest day of the year.
She concluded by explaining that the equinox is one of four key astronomical events that define the changing seasons: the spring and autumn equinoxes, when day and night are nearly equal, and the summer and winter solstices, when day and night are at their extremes. These shifts are driven by the sun’s angle relative to the equator and a location’s geographical latitude.
