stars

[Bazile]

Are there any stars that we could see , but which has now ' dissapeared ' ?

[TeeGee]

Quite probably. If one celestial body moves across the light path of another then it will seem to us that the further one will have disappeared. Also, from time to time, stars die off, get too dim for us to see and so on.

[jake-the-peg]

The Crab nebula is the remnant of a star that was distroyed in 1054

http://en.wikipedia.org/wiki/Crab_nebula


This is one that went off in 1604
http://en.wikipedia.org/wiki/SN_1604

is that the sort of thing you mean or do you mean variable stars? Omicron Ceti was the first variable to be identified way back in 1596.

it varies between 2nd and 10th magnitude. a magnitude 2 star is quite bright and is 2.5 times brighter than a mag 3 which is 2.5 times brighter than mag 4 etc.

6.5 is said to be the limit of naked eye visibility making omicron ceti the original "now you see it now you don't act"