The third cosmic speed (16.7 km / s) is the speed that must be imparted to a cosmic body in the vicinity of the Earth in order for it to leave the solar system forever. Why is this speed less parabolic for the Sun at the distance of the Earth?
Taking into account the orbital speed of the Earth (29.8 km / s), when launched in the direction of the planet’s motion, the speed of the spacecraft will be 46.5 km / s, which exceeds the parabolic speed for the Sun at the distance of the Earth. Excess energy is needed to overcome gravity. If the mass of the Earth were small, then the third cosmic speed would be only 12.3 km / s.
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