Cosmic Velocity - Third to Kilometer per Second

The third cosmic velocity is approximately 16,700 m/s (16.7 km/s), the minimum speed to escape the Sun's gravity from Earth's orbital position.

v₃ = √(v_sun² - v_Earth²) where v_sun is solar escape velocity from Earth's orbit. Approximately 16.7 km/s relative to Earth.

To km/h: × 3,600. To mph: × 37,282. 16.7 km/s = 60,120 km/h = 37,344 mph.

Voyager missions, future interstellar probes, and calculations for leaving the solar system.

Voyager 1: ~17 km/s relative to Sun (achieved via Jupiter gravity assist). Parker Solar Probe: 163 km/s peak (but toward Sun, not away).

Thinking Voyager was launched at 16.7 km/s — it used gravity assists. Also, confusing with speed needed to escape from Sun's surface (618 km/s).

~17 km/s to leave the solar system from Earth's orbit. Voyagers achieved this with gravity assists from planets.

Kilometer per second measures how many kilometers an object travels in one second. Used for very high-speed phenomena like spacecraft, asteroids, and planetary motion.

1 km/s = 1,000 m/s = 3,600 km/h. There are 1,000 meters in a kilometer.

To m/s: × 1,000. To km/h: × 3,600. To mph: × 2,237.

Earth's orbital speed: 29.78 km/s. Moon's orbital speed: 1.02 km/s. Space shuttle orbital speed: 7.8 km/s. Meteor entry: 11–72 km/s.

Solar system escape velocity: 42 km/s. Voyager 1 speed: 17 km/s. Fastest star (S4714 near black hole): 24,000 km/s (8% light speed).

Underestimating the scale — 1 km/s is 3,600 km/h, extremely fast. Confusing with m/s (1000× smaller).

Think of km/s as 'space speeds.' Earth orbits at ~30 km/s. To escape Earth: 11.2 km/s. Moon orbit: ~1 km/s.