1 It varies.

Geospace, which surrounds Earth, is thick with atmospheric atoms and electrically charged particles. Intergalactic space contains at best one lonely hydrogen atom per cubic meter.

2 Apollo astronauts were exposed to it.

The spacecraft's urine-management system was not much more than a tube connecting penises to the vacuum outside. Some astronauts report that they mistook their own crystallized urine for stars.

3 It wouldn't kill you right away.

In sci-fi movies, exposure to the vacuum causes humans to instantly freeze solid or burst. In actuality, you'd die from asphyxiation; and in minutes, not seconds. But there are earthlings that can withstand it for much longer: European Space Agency tests show that extremely tough little arthropod-like creatures called tardigrades can somehow survive in the vacuum for up to 10 days.