Tidal forces are a red herring in this kind of discussion. A black hole with an event horizon in the millions of kilometers would not expose you to dangerous tidal forces and you would indeed pass right on through. I’m not sure I agree that you wouldn’t notice at all, because there would have to be some serious relativistic effects, but maybe if you closed your eyes you wouldn’t notice.
Yeah, if you’re falling into a black hole, then at some point the tidal forces will get you, but where that point is has no particular relationship to the event horizon. It’s even possible to cross an event horizon in a region of space that is literally perfectly flat: For all we know, we could have crossed an event horizon just now. But that requires something of a cosmic conspiracy to pull off.
Let’s assume the ISS is in a pretty much circular orbit. The ISS is traveling at about 28,000 km/hr.
The baseball is now orbiting the Earth in a slightly more eccentric orbit than before. One point on the baseball’s new slightly more elliptical orbit is the spot it was in before you threw it. This is it’s new apogee, the highest point in it’s orbit. It’s new lowest spot, perigee, will be exactly on the other side of the Earth. If the ISS would stay in one spot the baseball would orbit around the earth and smack into the back of the astronaut’s head.
Except that won’t happen, because the ISS is orbiting the earth every 93 minutes, and by the time the baseball orbits around the earth (slightly less than 93 minutes), the ISS won’t be there anymore.
The baseball is in a smaller orbit, traveling faster. It could eventually smack into the ISS at 60 km/hour after enough orbits since the baseball and the ISS share a point in their orbits, but more likely small deviations in its orbit caused by small differences in the mass of the earth and position of the sun and moon mean that it will never smack into the ISS except by chance.
Oh, and I forgot to mention, the ISS will end up in a very very slightly higher and slower orbit after the astronaut throws the ball, simple action-reaction. If the ISS were in a perfectly circular orbit (which it isn’t), then the point where the ball was thrown becomes the new perigee, and the point opposite becomes the new apogee.
The ball does not fall to the earth, because it was orbiting at 27,000 km/hr and it would take a very large change in velocity to cause it to deorbit and fall to the Earth. Even shooting a bullet at the Earth wouldn’t be fast enough.
Of course the ISS isn’t very high up, and so eventually over the years there will be collisions with stray atmospheric particles that will slow the orbit of the ball, or the bullet, or the ISS, and eventually they’ll slow down due to friction with the atmosphere and intersect the Earth.
The baseball’s starting point would only be its apogee if you threw it straight back, not straight down.
Oh, and one of the Master’s humble minions has already written about this.
Good article! I was going to ask how you possibility knew it had been written! 