The International Astronomy Center has issued a critical warning to observatories and amateur skywatchers across the Arabian Peninsula, cautioning against directing telescopes or binoculars toward the Moon at sunset on Tuesday due to severe safety risks.

The center emphasized that observing objects extremely close to the Sun without certified solar filters may cause temporary or permanent blindness and could irreparably damage optical equipment.

Engineer Mohammed Shawkat Odeh, Director of the center, explained that at sunset on Tuesday the Moon will appear almost adjacent to the Sun throughout the Arabian Peninsula. In Riyadh, for example, the angular separation between the Sun and the Moon will be only one degree at sunset.

Since this measurement is calculated between the centers of the solar and lunar discs, the crescent—assuming it existed—would lie roughly half a degree from the Sun’s edge, placing it dangerously close within the telescope’s field of view.

Odeh stressed that any telescope aimed at the crescent’s calculated position at that time could inadvertently capture direct sunlight, exposing observers to serious ocular injury and threatening sensitive optical components.

Professional observatories, he noted, categorically avoid observing celestial objects in close proximity to the Sun unless stringent solar safety protocols and certified filters are employed. Waiting until the Sun has completely set would not resolve the issue, as by then the lower limb of the Moon would have already dipped below the horizon, leaving no crescent to detect.

Supporting these findings, astronomical data shared by researcher Mulham Hindi of King Abdulaziz University indicate that the Moon’s maximum altitude above the visible horizon in Saudi Arabia on Tuesday will be approximately half a degree in Jazan—well below the visibility threshold historically discussed by the scholar Ibn Taymiyyah, who stated that a crescent at one degree or less cannot be seen.

Odeh clarified that the celestial body present in the sky that day is the Moon in conjunction (new moon phase), not a visible crescent. A crescent is a specific lunar phase recognized only when it becomes observable.

The day of observation will also coincide with a solar eclipse visible from southern Africa and Antarctica, marking the peak of the new moon phase. In the Arabian Peninsula, the Moon will set shortly after the eclipse, leaving insufficient time for it to transition into a visible crescent phase.

Accordingly, the Moon setting shortly after sunset on Tuesday remains in the new moon phase and cannot be classified as a crescent unless it is actually sighted.

The center’s advisory underscores both the scientific impossibility of crescent visibility under these conditions and the paramount importance of strict observational safety standards.