Let me clarify, I'm not asking if a miracle happened, or for a scientific explanation for why the sun might appear to do what was claimed. I'm asking about the actual numbers... if there is any verification for the claims that "thousands" of people saw a strange solar phenomena?
Though there are discrepancies in the numbers, it's a very popular claim by very religious Catholics (and some others) that "thousands" witnessed a strange solar phenomena...
Although an hundred thousand individuals, from many diverse faiths and from no faith, spread out even over several miles, saw the “miracle of the sun,” Source
Gathered in the Cova da Iria near Fatima, an insignificant rural community in the countryside in Ourém in western Portugal, about 110 miles north of Lisbon, were an estimated 40,000 to 100,000 witnesses Source
Certainly some people claim they saw something odd. And certainly thousands were present on that day. Source
HOWEVER... Is there any evidence that thousands claim they saw this phenomena? The only statements I ever see (like in my two links above) claim thousands saw it without providing evidence for the numbers. What they tend to provide instead are anecdotes of a small handful of people who claim to have seen it combined with the fact that thousands were present and suggest this means thousands witnessed this phenomena. But that doesn't necessarily mean thousands claim to have seen anything out of the ordinary. It could have been a small handful of people making the claim and others misrepresenting the situation so it seems like thousands were making the claim.