1 December 2023

An orbit is a trajectory that a body experiences when it is around another, while it is under it. the gravitational forces. These can become circular, parabolic, hyperbolic or elliptical, the latter being the most common in the planets that make up the solar system. These are clearly explained through Kepler’s laws and Newton’s contributions. If you want to know what orbits are, what their characteristics are, the different types of orbits and more, here we will show you.

Concept and definition of orbit

In physics, an orbit is defined as the trajectory that a body travels in space thanks to the gravitational action that the stars perform on a body. In other words, it is when a body moves around a center of gravity to which it is attracted by a certain force. However, despite the fact that this force exists, the body will never come to impact with it nor will it be able to move away completely.

The study of orbits was born thanks to the contributions of Johannes Kepler, who, through his contributions, described three fundamental laws for the understanding of planetary motion. During the 17th century, while studying the universe and its motion, Kepler proposed the first law of it.

In it, he mentioned that the planetary orbits in the solar system are elliptical. Opposing the popular belief of the time, where they were considered to be circular. In the same way, he clarified that the sun is in one of its foci and not in the center of its orbits. It is important to remember that there are some artificial satellites in space, which have different orbits.

In his second law, he established that the speed of the orbits of each planet it is not constant. On the contrary, it depends on the distance from the planet and the sun. Reason why, it varies depending on each planet, for example, the lunar orbit would be different from the orbit of other planets.

The last of his laws, Kepler discovered that there was a universal relationship between the properties of the orbits around our sun. Therefore, for each planet in the solar system, the distance from said planet to the sun will be equal to the period of the planet raised to the square. Years later, Isaac Newton demonstrated that Kepler’s laws derived from his universal law of gravitation, where the force of gravity on bodies and their due attractions are studied.

Likewise, the word orbit is also used in other areas, such as atomic physics. In addition, it refers to a part inside the skull that is made up of seven bones that have the task of contain and protect the eye. Including the nerves and all the muscles that connect in said ocular area. This part of the body is known to be highly susceptible to eye cancer, which can be benign or malignant and often arises as part of metastasis from cancer of the breast, eyelid, eye, or compartments within the skull.

What is Earth’s orbit or Earth orbit?

Like all planets, the Earth moves around the sun. in an elliptical path. Each revolution of the Earth towards the sun takes 365 days and six hours, demonstrating at the same time a movement of translation. Thanks to this, it is that a certain degree of rotation is shown on the planet, which is why it causes the changes of the four seasons and the changes in the physics and chemistry with respect to the earth of the soils.

However, our planet does not have a single orbit, in fact, there are four possible orbits, which sun:

  • The low orbitknown by its abbreviation as LEO, is the one that is found from 200 to 2 thousand kilometers from the surface of the planet.
  • The medium orbit (MEO) is the one that covers the 2 thousand kilometers to the 35,786 km of the planetary surface.
  • The high orbit (HEO) is found from 35,786 kilometers to 40,000 km from the earth.
  • On the other hand, it is said of the existence of a fourth orbit, which is known as geostationary (GEO) which is from the 35,786 km of the earth’s surface of our planet. This orbit is synchronized with the equator line.

What is a planetary orbit?

The planetary orbits are the ones that correspond to the elliptical trajectories made by the planets of the Solar System. These work in such a way that they take a center, which is the sun, which will cause its gravity to keep the rest of the planets in constant motion. The speed of this movement will depend directly on the distance that each planet has from the sun, since the further away they are, the slower they rotate.

What is the shape of the orbits?

orbits can have various shapessince they can be elliptical, circular, elongated, parabolic or hyperbolic.

What is an elliptical orbit?

An elliptical orbit is one that has an ellipse shape, that is, that its circumference it is not completely round. On the other hand, it has a flattened and elongated shape. Elliptical orbits are characterized by having two central axes of each of the circumferences that generate it respectively, thus having two foci.

Similarly, in astrodynamics, they have a eccentricity greater than 0 and less than 1. In other words, the parameters that determine its degree of deviation make it possible to distinguish that one of these values ​​is equivalent to a circular orbit. While the other represents a parabolic orbit.

This type of orbits represent a movement whose trajectory is observed through an ellipse, being very common when analyzing a star. Reason why, its specific energy is negative.

Elliptical orbits always present two notable points in their trajectory, which are the periapsis and apoapsis. The first is the place that is closest to the central body. While the apoapsis, is the opposite. Therefore, it is defined as the farthest place from the path of the orbit.

What are the characteristics of an orbit?

  • Planetary orbits mostly they are circular in shape.
  • The movement that follows the trajectory of an orbit and that allows the bodies to orbit each other, is thanks to the force of gravity. This also allows them to stay on the same orbit, which means that they do not get far enough from the body they orbit, but they do not collide with it either. Keeping like that, at a prudent distance.
  • Each orbit has its own eccentricity.
  • Although they have different shapes, all of them are ultimately oval.
  • All orbits have many salient elements, such as their inclination, mean anomaly, their perihelion parameters, eccentricity, and more.
  • Each orbit has its certain periodsince this depends on the distance that the planet has from the sun.

What are the types of orbits?

On a theoretical level, there are many types of orbits, which are classified depending on their characteristics, by the type of central body and by their complexity. In the first group, we find the following varieties of orbits.

  • circulars: are those that arise when the gravitational forces have a fixed distance surrounding the barycenter, thus forming a circle.
  • Ecliptic: is the orbit that represents the curve through which the sun passes around the planet Earth. This type of orbit forms an intersection with the plane of the main terrestrial orbit with the celestial vault.
  • Cemetery: is the one that passes above the geostationary orbit. Its name is due to the fact that it represents the cemetery of artificial satellites that have fallen into disuse.
  • inclined: are those that arise when a body orbits around another and that the resulting angle in said orbit in relation to a reference plane must be other than 0 degrees.
  • synchronous: they happen when the orbital period of the object that it is orbiting is equal to the period of rotation of the other body in which it orbits. They even orbit in the same direction.
  • osculating: are the orbits whose current orbital vector state matches its position and velocity. These are represented as an object in space that, at one time, was Kepler’s orbit.
  • Hohmann transfer: are those that represent the orbital maneuvers that allow a spacecraft to move from one circular orbit to another. This was proposed in 1925 by Walter Hohmann.

Now, another of the classifications of the orbits is given by the core body guy to which they correspond. This division of the types of orbits allows us to find the terrestrial, the martian, the solar, the lunar and the galactic.

Finally, another of the types of orbits are those that have greater complexity or whose appearance can be easily differentiated from the others. Among this type of orbits we can mainly observe those that resulted from the observation of certain scientists, finding us with:

  • Kepler’s orbits.
  • Box-shaped orbits.
  • Halo orbits.
  • Lissajous orbits.
  • Horseshoe Orbits.

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