Leviämisnopeuden

Leviämisnopeuden, often translated as "escape velocity," is the minimum speed an object without propulsion needs to completely escape the gravitational pull of a massive body. Imagine throwing a ball upwards. Gravity pulls it back down. If you throw it faster, it goes higher before returning. Escape velocity is the speed at which the ball would never return, continuing outwards indefinitely.

The concept of leviämisnopeuden is derived from equating the kinetic energy of an object with its gravitational potential energy. For a celestial body like Earth, the leviämisnopeuden at its surface is approximately 11.2 kilometers per second (about 25,000 miles per hour). This means a rocket needs to reach this speed to leave Earth's orbit and travel into deep space.

The leviämisnopeuden depends on the mass of the celestial body and the distance from its center. More massive bodies have a higher leviämisnopeuden, as do objects closer to the center of a body. For example, the Sun's leviämisnopeuden is significantly higher than Earth's. It's a fundamental concept in orbital mechanics and space exploration, determining the energy required for spacecraft missions.