The sun's halo adorns the Saudi Arabian sky... Jeddah astronomer reveals the secrets

The Jeddah Astronomical Society revealed details of one of the most beautiful and astonishing atmospheric phenomena that graces the skies of the Arab world during winter: the "sun halo." The society's president, Engineer Majid Abu Zahra, explained that this time of year is the most suitable for observing this magnificent ring of light that surrounds the sun's disk, giving the sky a dramatic and captivating spectacle.

The scientific explanation for the 22-degree aura phenomenon

Abu Zahra explained that the solar corona appears as a circular ring with an angular diameter of 22 degrees. It is not an astronomical phenomenon in the traditional sense related to planetary motion, but rather a purely "optical-atmospheric" phenomenon. This corona results from the physics of light and its interaction with Earth's atmosphere, specifically when sunlight passes through thin, high-altitude clouds known as cirrostratus clouds.

Although the weather may be mild or warm at the Earth's surface, temperatures in the upper atmosphere (at an altitude of 6 to 13 kilometers) are extremely low, reaching freezing point. This extreme cold allows for the formation of millions of tiny ice crystals.

The role of hexagonal ice crystals

The head of the Jeddah Astronomical Society pointed out that the secret lies in the shape of these ice crystals, which are often hexagonal and resemble small pencils in their structure. These crystals act like natural "glass prisms"; when sunlight falls on them, it refracts at a specific angle (22 degrees) and is deflected, resulting in the formation of the luminous ring. Sometimes, the white light is broken down into the colors of the spectrum, so the inner edge of the halo appears faintly red, while the colors gradually become blue or white at the outer edge.

Folklore and weather forecasting

Historically, the phenomenon of the sun's halo (or moon's halo) has been associated in folklore and ancient cultures with changing weather patterns. Farmers and sailors often considered the appearance of this halo an omen of approaching storms or rainfall within 24 hours. Scientifically, this belief holds considerable truth, as the high cirrus clouds that create the halo often precede warm air fronts that bring rain and unsettled weather.

Similar phenomena and important warnings

Abu Zahra discussed the difference between the halo and other phenomena, such as a corona, which is caused by the diffraction of light through water droplets (not ice), and diamond dust, which occurs in extremely cold regions near the Earth's surface. He also noted that the halo is characterized by the area inside the ring appearing darker than the outside because there are no crystals to refract light towards the eye in that area.

The Jeddah Astronomical Society concluded its warnings by emphasizing the need for extreme caution when observing this phenomenon. Abu Zahra stressed the danger of looking directly at the sun, even for a moment, advising observers to shield the sun from view behind a building or lamppost to see the corona clearly and safely, and to avoid looking directly through camera lenses to protect the retina from burns.