I know how they stay in orbit but how do random planets and stuff have the exact speed needed to get to orbit? Is it pure chance or some phenomenon that speds them up or slows them down?
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As in, planets orbiting around the sun? Mostly they started with that much energy, the stuff that wasn’t in the range of velocities compatible with orbiting either fell into the sun or flew off into interstellar space. The rest coalesced into planets in roughly the same orbits as the original material, occasionally colliding with other stuff.
Gravity speeds you up as you get closer to a massive object, and slows you down as you get farther away. An eccentric orbit has you moving slower at the high point of your orbit than a circular orbit at that altitude, and faster at the low point of your orbit than a circular orbit at *that* altitude.
To get from Earth’s surface to low earth orbit, you need enough fuel to change your velocity by about 9km/s. Most of that is spent accelerating you sideways, the rest is spent on gravitational potential energy, gravity losses, aerodynamic losses, and steering losses. Once you get to low earth orbit, you need to go about 3km/s faster to escape Earth’s gravity well into a solar orbit.
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