That was over 35 years ago in 1986.
Today she is 71, and has starred in 94 movies in total, 81 since Aliens was released.
In Aliens, I think Sigourney Weaver looks:
Aliens scores 7.8 out of 10 on The Movie Database.
Sigourney Weaver's first acting role was as 'Alvy's Date Outside Theatre' in Annie Hall, released in 1977 when she was 27.