Earth Satellite – Class 11 | Chapter – 8 | Physics Short Notes Series PDF for NEET & JEE

Earth Satellite: An Earth satellite is any object that orbits around the Earth. There are two main types of Earth satellites: natural satellites, which are also known as moons, and artificial satellites, which are human-made objects.

Types of Earth Satellite

  • Natural satellites: The Earth has one natural satellite, the Moon, which is the fifth largest moon in the Solar System. The Moon is about one-quarter the size of the Earth and orbits around the Earth once every 27.3 days.
  • Artificial satellites: Artificial satellites are man-made objects that orbit around the Earth. There are thousands of artificial satellites in orbit around the Earth, including communication satellites, navigation satellites, weather satellites, and scientific research satellites. These satellites are launched into space using rockets and are designed to carry out specific functions while in orbit, such as transmitting data, providing weather information, or studying the Earth’s atmosphere.

Orbits of Earth Satellite

Satellites are typically placed in one of three types of orbits around the Earth: geostationary orbit, polar orbit, or low Earth orbit.

  • Geostationary orbit: Satellites in geostationary orbit are placed at an altitude of about 36,000 kilometers above the equator, and orbit the Earth once every 24 hours, which is the same time it takes for the Earth to rotate on its axis. This means that the satellite appears to be stationary in the sky, making it ideal for communication and broadcasting purposes.
  • Polar orbit: Satellites in polar orbit pass over the Earth’s poles and travel from north to south and back again. This type of orbit is often used for weather and environmental monitoring, as it allows the satellite to cover the entire surface of the Earth.
  • Low Earth orbit: Satellites in low Earth orbit are placed at an altitude of a few hundred kilometers above the Earth’s surface and orbit the Earth once every 90 minutes or so. This type of orbit is often used for scientific research and reconnaissance purposes.

Projectile Nature of Earth Satellite

An Earth satellite is a projectile in orbit around the Earth. In other words, it is an object that has been launched into space with enough initial velocity to overcome the Earth’s gravitational pull and is now moving under the influence of gravity in a curved path around the Earth.

Like any projectile, a satellite moves in a parabolic path due to the force of gravity acting upon it. However, because of the Earth’s curvature and the continuous pull of gravity, the satellite’s path is not a simple parabola, but a closed elliptical orbit around the Earth.

The speed of an Earth satellite depends on the altitude of its orbit. Satellites in higher orbits have a lower speed than those in lower orbits because the gravitational pull of the Earth is weaker at higher altitudes. For example, a satellite in a geostationary orbit (at an altitude of 36,000 kilometers) travels at a speed of about 11,000 kilometers per hour, while a satellite in a low Earth orbit (at an altitude of a few hundred kilometers) travels at a speed of about 28,000 kilometers per hour.

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By Team Learning Mantras