Johnny Galecki is a Belgian-born American actor, best known for his roles as David Healy in Roseanne, Rusty Griswold in National Lampoon's Christmas Vacation, and as Leonard Hofstadter in The Big Bang Theory.
Seveneves is a hard science fiction novel by Neal Stephenson published in 2015. The story tells of the desperate efforts to preserve Homo sapiens in the wake of apocalyptic events on Earth following the unexplained disintegration of the Moon, and the remaking of human society as a space-based civilization after a severe genetic bottleneck.
