Also, the observers may squint or shade their eyes to aid viewing. I remember when an eclipse was going to be visible and everyone was cautioned NOT to look directly into the sun for fear of sight damage or blindness. A wise precaution although it would require more than a momentary glimpse to produce any permanent optic damage. My infant daughter got her eyes damaged from looking at the sun and they swelled shut and had to be completely covered for an entire day. There were no reports of eye damage or blindness from this occurrence.
Children are highly-susceptible to such things.
It should be noted that many contemporaries of Galileo examined the Sun with telescopes and were not permanently blinded. I even have personal experience in this issue. After dinner one evening, she went outside the convention center for a cigarette and noticed everyone looking up at the sky. She looked at the sun, saw what was happening, and ran back into the building to find me. She took me outside and directed me to look at the sun.