Definition
The minimum speed an object must reach to break free of a celestial body's gravitational pull without any further propulsion. For Earth, escape velocity is approximately 25,000 mph (about 7 miles per second, or 11.2 km/s) at the surface.
Plain English
The speed something must travel to leave a planet's gravity behind for good and not fall back down.
Context Anchor
Seen in aerospace, rocket, and high-altitude flight discussions when comparing the pull of gravity from Earth, the Moon, or another body.
Derivation
From Latin 'velocitas' (speed) and 'escape' (from Old French 'eschaper', to get free). Together: the speed at which something gets free of gravity's hold.
Why Pilots Care
Most pilots do not calculate escape velocity in normal flying, but the term helps separate ordinary aircraft flight from spaceflight, where gravity and speed are discussed on a much larger scale.
Analogy
Imagine throwing a ball straight up. Throw it gently and it falls back. Throw it harder and it goes higher before falling back. Escape velocity is the threshold speed where the ball never comes back down at all.
Grounding Statement
Near Earth, escape velocity is very high because Earth's gravity is strong; near the Moon, it is lower because the Moon's gravity is weaker.
Intuition Check
Escape velocity does not mean the speed to escape danger or weather. It means the speed needed to escape a body's gravity without more push.
Example Sentence 1
A spacecraft headed to the Moon must reach escape velocity to break free of Earth's gravitational pull.
Example Sentence 2
Pilots studying advanced performance calculations sometimes review escape velocity when considering ballistic trajectories beyond the atmosphere.