With all the technological marvels we have today, it is tempting to think that we have all the answers. However, the reality of the situation is far different: many of the fundamental questions about the nature of the universe are still unanswered. Here are the things that keep cosmologists up at night.

Space is loaded with strange things—black holes, pulsars, gigantic clouds of alcohol, and more weird planets than you could count. Even our own solar system has some oddballs—like Neptune.

Humans have been fascinated by the thought of aliens for centuries now, and it’s hard not to wonder—are we alone? The universe is vast, and we haven’t even uncovered 1% of it.