how did Galileo see the sun so clearly without going blind?

Question

if possible the site too! thanx

Answer 1

at the end of his life he was blind

Answer 2

In fact, Galileo did go blind in his old age, quite likely from looking at the Sun with his telescope. He had no way of knowing that it was dangerous until it was too late.

Answer 3

I can't resist the flippant answer: he lived in the dark ages!

Anyway, if you're referring to his discovery of sunspots or some such: if technology in his day was sufficiently advanced for him to have a telescope, it was surely advanced enough for him to have access to darkened glass of some sort. There are lots of ways in which he could have dealt with the issue of the sun's brightness; the exact method he used probably isn't all that important.

Answer 4

The same way we're taught to observe sunspots: he used his telescope to project the image of the sun onto a sheet of paper and drew the marks where they fell on the sheet.

Answer 5

Most likely, he passed the sun's image through lenses & focused them on something - paper, marble - not such that the light was focused to a hot white spot, but so the image of the sun could be seen as a true image on some flat object.