Space is a vacuum, but stepping outside a spaceship without a suit wouldn’t kill you instantly. You wouldn’t explode, and your blood wouldn’t boil—Hollywood gets that wrong. Instead, you’d pass out in about 15 seconds from lack of oxygen. After a minute or two, things would turn fatal. But for a few moments, you’d still be conscious enough to notice the saliva on your tongue start to bubble (because of low pressure) before everything fades to black.