what is that movie (probably from 70's or 80's) where people have to leave earth in search for a new planet?

Question

I've seen this movie when I was a kid like 20 something years ago,where people had to leave the earth for good,watched it blow up as they were leaving and then went on to search for a new planet to live on.Can't think of the name of the film.HELP!!!

Answer 1

The only one that `springs to my mind is the original version of Battlestar Galactica.

Answer 2

Perhaps, The Doomsday Machine (1972):

Spies discover that the Red Chinese have built a "doomsday machine" capable of destroying the surface of the Earth, and that they plan to use it within a matter of days. Meanwhile, Project Astra, a manned U.S. space mission to Venus, is in its final hours before launch when it is taken over by the military and nearly half of its all-male crew is replaced by women. The reason for this becomes apparent when, shortly after Astra leaves orbit, the Earth is completely destroyed in a global cataclysm.

Answer 3

Planet of the apes