What’s the critical distance from Earth and why does everything on Earth escape its gravitational pull to leave and travel through space?
The critical distance from Earth, also known as the escape velocity, is the minimum speed an object must have to escape Earth's gravitational pull and travel indefinitely through space. The escape velocity at Earth's surface is approximately 11.2 kilometers per second (7 miles per second).
Objects on the surface of Earth do not escape into space because they are constantly accelerating towards the center of Earth due to gravity. This acceleration is equal to the force of gravity, which is given by the formula:
F = G * (m1 * m2) / r^2
where:
- F is the force of gravity
- G is the gravitational constant (6.67430 x 10^-11 N m^2/kg^2)
- m1 is the mass of the first object (Earth)
- m2 is the mass of the second object (the object on Earth's surface)
- r is the distance between the two objects
Because the mass of Earth is so much larger than the mass of any object on its surface, the force of gravity is always pulling the object towards Earth. The only way an object can escape Earth's gravity is if it is moving fast enough to overcome this force.
The escape velocity is not the same for all objects. It depends on the mass of the object and the distance from the center of the planet. For example, the escape velocity at the top of Mount Everest is about 11.1 kilometers per second, slightly less than the escape velocity at sea level. This is because Mount Everest is farther from the center of Earth than sea level.
The escape velocity is also not the same for all planets. The escape velocity of a planet depends on its mass and radius. For example, the escape velocity of Jupiter is much higher than the escape velocity of Earth because Jupiter is much more massive.
Objects that escape Earth's gravity can travel through space until they encounter another gravitational field that is strong enough to capture them. For example, a spacecraft that escapes Earth's gravity will eventually encounter the Sun's gravity and will orbit the Sun.
Even though objects escape Earth's gravity, they are still subject to the Sun's gravity. The Sun's gravity is much stronger than Earth's gravity, so all objects in the solar system are ultimately orbiting the Sun.
The maximum Sun-Earth distance is at aphelion position (about 152 million kilometers) and the minimum distance is at perihelion position (about 147 million kilometers). This boundary sits some 62 miles (100 kilometers) above Earth's surface, and it's generally accepted as the place where Earth ends and outer space begins. Earth's circumference is the distance around Earth. Measured around the equator, it is 40,075.017 km (24,901.461 mi). Measured around the poles, the circumference is 40,007.863 km (24,859.734 mi). Finally, the most probable fate of the planet is absorption by the Sun in about 7.5 billion years, after the star has entered the red giant phase and expanded beyond the planet's current orbit. A speed of over 40,250 km per hour, called escape velocity, enables a rocket to leave Earth and travel out into deep space. Attaining space flight speeds requires the rocket engine to achieve the greatest action force possible in the shortest time. Escape velocity refers to the minimum velocity an object must attain to overcome Earth's gravitational force and achieve an unbounded trajectory away from the planet. This speed is crucial, as any object that fails to reach the escape velocity will remain bound by Earth's gravitational influence. Fortunately for us, Earth's gravity is strong enough to hold onto its atmosphere. Mars, for example, is less than half Earth's size and around one-tenth Earth's mass. Less mass means less gravitational pull. An invisible force that pulls objects toward each other and Earth's gravity is what keeps you on the ground and what make things fall. Anything that has mass also has gravity. Escape velocity for earth is about 11.2 km (6.96 miles) per second. That's where the effects of gravity are overcome by the kinetic energy of the spacecraft. The sun also has an escape velocity. It's about 615 km per second. Escape velocity is the minimum speed needed for a free, non-propelled object to escape from the gravitational influence of a massive body. The escape velocity from Earth is about 11.186 km/s (6.951 mi/s; 40,270 km/h; 36,700 ft/s; 25,020 mph; 21,744 km) at the surface. The value of standard gravity corresponds to the gravity on Earth at a radius of 6,375.4 kilometres (3,961.5 mi).