Partial Solar Eclipse on September 21, 2025
On Sunday, September 21, 2025, residents of certain regions in the Southern Hemisphere will witness a spectacular astronomical event: a partial solar eclipse, also known as an "equinox eclipse." The event will be visible in New Zealand, parts of the Pacific Ocean, and Antarctica. At its maximum, the Moon will cover approximately 85.5% of the solar disk, a celestial alignment that will last over four hours.
According to Professor Ashraf Tadrès, an astronomer at the National Institute of Astronomical Research in Egypt, this eclipse will not be visible in Egypt or the rest of the Arab world. "A solar eclipse occurs only during the new moon phase, when the Moon passes between the Earth and the Sun, casting its shadow on our planet," he explained. In contrast, a lunar eclipse occurs only during a full moon, when the Earth comes between the Sun and the Moon.
This particular configuration does not occur every month due to the Moon's orbit being inclined at an angle of about five degrees relative to the Earth's orbit. For a solar or lunar eclipse to occur, the Moon must be close to one of the two orbital nodes – the points where its orbit crosses the plane of the ecliptic, which is the Earth's orbit around the Sun.
The phenomenon on September 21 will last a total of four hours and twenty-four minutes. The maximum eclipse, with 80% solar coverage, will be observable in the Southern Ocean, between New Zealand and Antarctica. On the Antarctic Peninsula, the coverage will not exceed 12% just before sunset.
Beyond the fascination they inspire, these eclipses have great scientific importance. They allow for precise verification of the beginning and end of lunar months, which is the basis of the Islamic calendar, and for studying the Moon's movement around the Earth. "Eclipses are a clear demonstration of celestial laws and the harmony of planetary movements," added Tadrès.
The researcher also recalled the existence of the Saros cycle, a periodicity discovered in ancient times by the Babylonians, Chaldeans, and Egyptians. This cycle, which lasts 18 years, 11 days, and 8 hours, corresponds to approximately 223 lunar months. After this period, the Earth, Moon, and Sun return to nearly the same relative positions, resulting in similar solar and lunar eclipses to those observed previously.
The eclipse on September 21 is the second and last solar eclipse of 2025. The previous one occurred earlier in the year, but in other regions of the globe. For astronomers and astronomy enthusiasts, this is an event not to be missed, especially since such a celestial alignment is rare.
Although the eclipse will only be visible in the Southern Hemisphere, it reminds the entire world of the precision of astronomical cycles. Thousands of enthusiasts, observatories, and scientific institutes will closely follow this event, a symbol of the regularity and beauty of the natural laws that govern our universe.
