UAE-based astronomers are warning members of the public of safety risks involved in trying to observe the moon through telescopes or binoculars on February 17, including temporary or permanent eye damage. This is due to the moon’s proximity to the sun on that day, which also coincides with the occurrence of a solar eclipse, they said.
Directly viewing the Sun through telescopes, binoculars, or optical instruments without certified solar filters may cause temporary or permanent eye damage, including blindness, Abu Dhabi-based International Astronomy Centre told Khaleej Times. Therefore, attempting to direct optical instruments toward celestial objects located very close to the Sun poses significant risk if proper professional safety standards are not strictly applied.
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Why does angular separation matter?
On Tuesday, February 17 — when moon-sighting committees around the world are expected to sight the crescent — the angular separation between the moon and the sun will be just one degree in Riyadh at sunset.
Khadijah Al Hariri, Operations Manager at Dubai Astronomy Group, confirmed this, explaining: “Even though the eclipse will occur earlier in the day, by sunset, when people normally go out to look for the crescent, the moon will still be extremely close to the sun.” [You can read about whether the eclipse will impact the crescent sighting here.]
Angular separation is measured between the centres of the sun and moon disks. This means that if the crescent exists, its distance will be approximately half a degree from the sun’s disk.
Thus, any telescope directed towards the crescent’s position during sunset will also have the sun either within its field of view, or extremely close to it, exposing both the equipment to damage and posing a real danger to the observer’s eye that could lead to permanent vision loss, the IAC said.
Astronomically impractical
Apart from being “dangerous for the eyes”, Khadija added that public attempting moon sighting through optical instruments on February 17 is also “astronomically impractical”.
The view echoed that of the IAC, which stated that even if the observer “waits for the sun’s disk to fully set before beginning observation, by then the moon’s lower edge will have naturally set, and there will be no crescent to search for”.
Last week, Oman became the first GCC country to officially announce start dates for Ramadan ahead of the moon-sighting. It cited the same impracticality as well as its principle of “not accepting reports that contradict observable reality or scientific certainty” as reasons for establishing the date in advance. Three other countries also followed suit in announcing February 19 would be the first day of Ramadan. [Read about the different ways in which countries determine when Ramadan starts here; spoiler alert: they’re not all dependent on moon-sighting.]
Clarification on advisory
The IAC told Khaleej Times it issued the safety warning on Friday to caution the public against “unsafe observation practices” such as using telescopes, binoculars, or other optical instruments without certified solar filters.
Professional astronomical observatories operate in accordance with internationally recognised safety protocols and use specialised equipment and certified solar filters when conducting observations under such conditions, IAC said in a statement to Khaleej Times.
IAC clarified that their role is limited to raising scientific awareness, and they are not the competent authority responsible for issuing official decisions concerning crescent sighting or the declaration of the beginning of lunar months.
