how were the rings of uranus discovered?

Question

also how are craters used to data the surface of a moon or planet?

thanks

Answer 1

The rings of Uranus were discovered during a study of an occultation. Sometime in the 70s Uranus was due to pass in front of a distant star. Astronomers hoped to use information about the way the star dimmed and disappeared as it passed behind the planet to learn about its atmosphere. Uranus has such an extreme tilt that it appears to be lying on its side, and at that time it had one of its poles pointed almost straight at Earth. While waiting for the planet to pass in front of the star, the astronomers were surprised to see the star 'blink' several times then return to full intensity before passing behind the planet, then do the same pattern of blinking shortly after emerging from the other side.

Astronomers reasoned that Uranus must therefore be surrounded by a ring system, and the blinking of the star was caused by the rings passing in front of it.

About a decade later the Voyager 2 probe passed Uranus and returned the first pictures of the rings. Voyager did not discover them, but did provide the first images of them.

And as to your second question, craters are used to date the surface of a planet or moon simply by counting them. A younger surface has fewer craters, and an older surface has more. This can be seen on the Moon, with many craters covering every availble mile of the lighter areas, but the younger, dark 'seas' being reasonably crater-free.

Answer 2

They were discovered by Voyager 2 during it's fly by in the 80's.

Answer 3

Both Bryan and Jason are right it was discovered by earth bound telescopes, and confirmed by voyager fyby

Answer 4

My proctologist discovered them.