>>433424773Generally speaking, the Sun’s gravity keeps the solar system together.
The stars do change position relative to Earth and there’s plenty of information on how the constellations have changed their appearance over time as observed from Earth. The reason one may think stars haven’t change position is because of the size of the galaxy, the distance between stars, and the distance between each star and Earth. It takes our solar system about 250 million years to complete one orbit around the center of our galaxy. Furthermore, with planets orbiting a central star, the orbital velocity of a planet is proportional to the planet’s radial distance from the star. This is not true in the case of stars orbiting the center of a galaxy, which orbit at about the same velocity regardless of their radial distance from the galaxy’s center. This does create slippage in the relative alignment of stars from Earth’s perspective but it occurs extremely slowly. Additionally, the greater the distance between an object stationary relative to a moving observer and the observer, the less apparent the change in distance will be, especially when orbiting a common center point.
We use rockets to launch satellites in space and doing so requires achieving escape velocity until the satellite reaches the desired distance from Earth at which point the satellite must maintain a corresponding orbital velocity otherwise it’ll get yanked back to Earth. At about 150 miles up, orbital velocity will be about 17k mph.
It’s not like throwing a ball out of a moving car because space is very empty (a vacuum) so there’s nothing to act upon the satellite. On Earth, the ball goes from being in air moving at the same speed to hitting a wall of relatively stationary air causing the ball to decelerate quickly.
There’s nothing in space to strip away the atmosphere. That said, I am curious why the atmosphere hasn’t diffused to fill up the emptiness of space.
