Will an astronaut be left behind when he steps out of his spaceship?
The reason why is, the astronaut and the spaceship are traveling
at the same speed.
The astronaut would have to careful though! Because, if the
astronaut pushed away slightly from the spaceship as the astronaut
stepped out, the astronaut would drift away from the spaceship and
would continue to drift across space forever, provided the
astronaut didn't bump into anything out there or get sucked in by
the gravity field of a planet or a star.
That's why when they do an EAV (Extravehicular Activity) they
have to either be tethered to the spacecraft or have a MMU (Manned
Maneuvering Unit). The MMU is kinda like a jet pack of sorts, it
lets the astronaut fly around the spaceship with compressed jets of