Viewing a single comment thread. View all comments

absoluteally t1_j24mxq3 wrote

Reply to comment by IsraelZulu in A *dumb* question, for a mixup by Independent-Choice-4

Escape velocity is contextual so depends where you are and how fast you are already going. I this case i believe they are starting from static in the surface(usually what is meant).

What it actually means is for the moon the escape velocity is the velocity change you would need from where you are to reach infinity with no excess velocity. Assuming there is nothing else in the universe.

But given they way gravity tails off escape velocity is often not meaningfully different from the velocity to leave the bodies dominant influence.

8

zoicyte t1_j24x0mn wrote

*contextual relative to the object you're trying to escape.

you need more speed to escape from the gravity of the earth than the moon.

the escape velocity to exit the solar system is really, really high, because you're trying to escape the pull of the sun itself. to date i think we have only launched 4 probes that have achieved the solar system's escape velocity (pioneer 10/11, voyager 1/2). it's possible the new horizons craft has reached the escape velocity for the solar system, it's certainly truckin'.

2