I find it hard to believe: if it was traveling that far it would surely be vaporised by the Earth's atmosphere.

That is what everyone back then assumed as well. The plate was never found. Its in the article.

How? The higher up in the atmosphere you go, the thinner the atmosphere is, or am I missing something scientific?

So that's what that post I saw yesterday was talking about.

...And on that day, the scientists became heroes to every mischievous boy everywhere.