Types of orbits and how orbits exist

An orbit is the gravitationally curved path of an object around a point or another object in space. In this article, we are explaining the types of orbits and the science behind them. The object in an orbit is called a “Satellite”. A satellite could be natural, like a planet, or man-made, like ISS (International Space Station). Many planets have moons that orbiting around them. And many more planets, asteroids, comets, and other objects in our solar system are orbiting around the Sun.

The Science behind orbits

Orbits have different shapes. It may be circular or oval. Orbits of planets are almost circular and comets’ orbits are more like a thin ellipse.

Satellites orbiting around objects do not always stay at the same distance to the object. It’s the same as the moon’s trajectory around the earth also. Sometimes, the moon gets so closer to the earth and sometimes it becomes far away from earth. The closest position of the planet or moon’s orbit around the earth is “Perigee” and the farthest position is “Apogee”. And when it comes to objects orbiting around Sun, the closest position is “Perihelion” and the farthest position is “Aphelion”. Earth has an orbital period around the sun of one year.

Object orbiting satellites have two factors that have an impact on them. Those are gravity and the satellite’s momentum. Gravity is the force that pulling the satellites towards the object. Momentum is the satellite’s tendency to move in a straight line off into space. The satellite’s momentum and pulling force of gravity from the object have to be balanced for an orbit to exist. If the forward momentum of a satellite is too great for the force of gravity, the satellite will speed past the relevant orbit and will not enter into an orbit. And if the force of gravity far lesser than forward momentum, then the object will crash down into the object.

Orbital Velocity

Orbital Velocity is the speed of a satellite needed to stay in orbit. As an example, for a satellite to stay in orbit at an altitude of 1500 km above the earth, the satellite must need an orbital velocity of nearly 15,900 mph according to the Australian Space Academy website. This orbital velocity decreases with increased orbital altitude. It means satellites that have higher altitudes have slower orbital velocity and lower altitude satellites have faster orbital velocities.

Types of Orbits

Satellites orbiting the Sun are in Heliocentric orbit and satellites orbiting the Moon are in lunar centric orbit. Likewise, when it comes to the Earth’s orbits, that satellites orbiting around the Earth stay in Geocentric orbit. Let’s see what are the types of Geocentric orbits because most of the man-made operational satellites are there. It’s more than 6,000. There are mainly 4 types of Geocentric orbits according to the altitude of orbits.

• Lower Earth Orbits (LEO)
• Medium Earth Orbits (MEO)
• Geosynchronous Orbit (GEO)
• Higher Earth Orbits (HEO)

Lower Earth Orbits (LEO)

Lower Earth Orbits are located in altitude from nearly 200 km to 2000 km from the mean sea level of Earth. But most of the man-made satellites are at an altitude of 161 km to 322 km. This is the easiest orbit to reach and stay in. Weather and photography satellites, Hubble telescope, and even International Space Station are orbiting in LEO.

Medium Earth Orbits (MEO)

Medium Earth Orbits ranging from 2000 km to 35000 km from Earth. Navigation satellites like GLONASS, GPS, and communication are examples of MEO satellites.

Geosynchronous Orbit (GEO)

GEO is located at 37,015 km above Earth’s equator. These orbits are also called Geostationary orbits. GEOs are Higher earth orbits but having a significant value than others. Satellites in GEO have an orbital period of 23 hours, 56 minutes, and 4 seconds which matches the Earth’s rotation on its axis. Communication, weather, and surveillance satellites are located in this orbit.

Higher Earth Orbits (HEO)

Orbits with an altitude of over 35,000 km from Earth are Higher Earth Orbits. Observing satellites that are using X and Gamma (γ) radiations are orbiting in HEOs.

So, it’s all we have to say about Orbits. We hope to bring you more about orbits and ISS in near future. At Inventho, we intend to give you more about Science, Technology, Space, Motivational and Inspirational stories in addition to aware you with latest news in the science world. Stay tuned with us by subscribing to our website or Facebook page.