Orbit (Meaning and Explanation)

We explain what an orbit is and what its meaning is in the area of chemistry. Also, elliptical orbits and orbits of the Solar System.

What is an orbit?

In physics, the orbit is the path described by one body around another around which it rotates by the action of a central force, such as the gravitational force in the case of the celestial stars. It is the trajectory that an object traces when moving around a center of gravity by which it is attracted, in principle without ever hitting it, but never completely moving away from it.

Orbits have been a concept since the 17th century (when Johannes Kepler and Isaac Newton formulated the basic physical laws that govern them). important for understanding motion in the universe especially with regard to the celestial stars and also to subatomic chemistry.

an orbit It can have different shapes, whether elliptical, circular or elongated and can be parabolic (shaped like a parabola) or hyperbolic (shaped like a hyperbola). In any case, every orbit includes the following six Keplerian elements:

Inclination of the plane of the orbit, represented by the sign i.
Length of the ascending node, represented by the sign Ω.
Eccentricity or degree of deviation of a circle, represented with the sign e.
Semi-major axis, or half the longest diameter, represented with the sign a.
Argument of the perihelion or periastron, the angle that goes from the ascending node to the periastron, represented with the sign ω.
Mean anomaly of the epoch, or the fraction of orbital time elapsed and represented as an angle, represented by the sign M0.

Orbit in chemistry

In chemistry, we talk about orbits regarding the movement of electrons around the nucleus atoms due to the difference in electromagnetic charges they present (negative in the electrons and positive in the nucleus of protons and neutrons). These electrons do not have a defined trajectory, but they are classically described as orbits known as atomic orbitals, depending on the degree of energy they harbor.

Each atomic orbital is expressed with a number and a letter. The number (1, 2, 3… up to 7) denotes the energy levels with which the particle moves, while the letter (s, p, d and f) denotes the shape of the orbital.

Elliptical orbit

An elliptical orbit is one that, instead of a circle, draws an ellipse, that is, a flattened and elongated circle. This figure, the ellipse, has two foci, where the central axes of each of the two circles that compose it would be; In addition, this type of orbit has an eccentricity greater than zero and less than one (0 is equivalent to a circular orbit and 1 to a parabolic one).

Every elliptical orbit has two notable points:

Periapsis The closest point on the orbital path to the central body around which the orbit is drawn (and located at one of the two foci).
Apoapsis The farthest point of the orbital path from the central body around which the orbit is drawn (and located at one of the two foci).

Orbits of the Solar System

Mercury - orbit — The planet Mercury has the most eccentric orbit, perhaps because it is closer to the Sun.

The orbits described by the stars of our Solar System are, as in most planetary systems, more or less elliptical type. At the center is the star of the system, our Sun, whose gravity keeps the planets in motion; while comets in their respective parabolic or hyperbolic orbits around the Sun do not have a direct link with the star. For their part, the satellites of each of the planets also trace orbits around each one, as the Moon does with the Earth.

Earth orbit

The Earth, like its neighboring planets, orbits the Sun in a slightly elliptical path which takes approximately 365 days (one year) and which we call translational movement. This movement occurs at about 67,000 kilometers per hour.

At the same time, there are four types of possible orbits around the Earth, for example, for artificial satellites:

Low orbit (LEO) From 200 to 2,000 km from the planetary surface.
Middle orbit (MEO) From 2,000 to 35,786 km from the planetary surface.
High orbit (HEO) From 35,786 to 40,000 km from the planetary surface.
Geostationary orbit (GEO) At 35,786 km from the planetary surface. This is the orbit synchronized with the Earth's equator, endowed with zero eccentricity and in which an object appears motionless in the sky to terrestrial observers.