In 1992, astronomers Alexander Walstein and Del Friel spotted the first two planets outside our solar system.

The two planets revolved around a neutron star, that is, the remnants of a large, devastating star that has a high gravitational force, located at a distance of 2,300 light-years from Earth, which confirmed the presence of several planets around the stars scattered in space.

This discovery prompted astronomers to search for more planetary systems, a term that refers to all objects that revolve around a star or a group of stars, and these objects include planets, meteorites, moons and comets, trying to find out how the systems are formed, in addition to research. About planets similar to Earth climatically.

On February 14, EurekAlert published a press release indicating that a method had been found to divide planetary systems into 4 specific recurring patterns, through two consecutive studies published in the Astronomy & Astrophysics journal. .

In the year 1992, astronomers, Wilstein and Friel, observed the first two planets located outside our solar system (NASA).

Planetary systems are not the same

Lokesh Mishra, a researcher at the NCCR Planets Department of the Swiss University of Bern, explains in his study that astronomers previously assumed that planets outside our solar system are similar to each other, calling them the term "Peas in a pod". ), meaning contiguous peas in the same pod.

The previous term indicates that the neighboring planets around a star are either close in size, or are larger than each other according to their arrangement, meaning that the planet farthest from the star is larger in size than the one that precedes it.

On this matter, Mishra says, "Previously, it was not easy to classify the planets according to the 'pea' theory, because the sizes of those planets may differ from this perspective, as is the case in our solar system."

Astronomers have assumed that planets outside our solar system are as similar as peas in their pod (Shutterstock)

A new method for revealing the structure of planetary systems

Mishra believes that the statistical methods used in some previous studies to model planetary systems are inaccurate and cannot be applied to all planets. These statistics depend on a comparison between a group of neighboring planets in a number of planetary systems, not within a single system.

So Mishra worked on developing a framework that enables him to determine the structure of the planetary system (the relationship between neighboring planets related to size) according to each of those systems separately, without comparing the multiple systems.

This framework aims to search for answers to some questions, including: How does the structure of the planetary system form based on the environment in which it originated?

What is the impact of developments within the system on its final structure?

(such as orbital migration, meaning the deviation of the planet from its natural path).

Jan Alibert, co-author of the study and professor of planetary sciences, explains the advantages of this method, explaining, "We can use the new framework to measure more than mass and volume, such as diameter, density, and quantities of water, and now we have a tool through which we can study planetary systems in full."

Classes of planetary systems (Jurik Alert - University of Bern)

Classification of planetary systems

The results of the two studies included the classification of planetary systems into 4 types: similar, ordered, anti-ordered, and mixed.

A similar system is one that includes neighboring planets that are similar in mass and size, and the ordered system includes planets that increase in size and mass as they are farther from the star around which they revolve, and our solar system belongs to this type.

As for the inversely arranged systems, the size and mass of the planets get smaller as they are farther from the star. Finally, the mixed system consists of planets that are not subject to any arrangement.

Mishra points out that the similar pattern is the most common among planetary systems. Among every 10 systems that appear clear in the sky, we find 8 that have a similar pattern, while the "arranged" pattern of our solar system is the least common of these patterns in galaxies.

Several factors influence the structure of the planetary system

Mishra states that the final shape of the planetary systems is affected by several factors, including what is known as the "protoplanetary disk", which is a disk consisting mostly of gases (about 99% of its mass) and dust atoms, and it revolves around a newly formed star, and contributes to the formation of Planets and the rest of the contents of the planetary system.

About that, he says, "Similar systems are produced from small disks of low mass that revolve around a star that contains few heavy elements, while ordered and inverse systems arise from large disks of high density belonging to stars that contain large amounts of heavy elements, and finally mixed systems arise from medium disks." the size".

"Kinetic interactions between the planets, such as collisions between them, contribute to shaping the final shape of the planetary system," he added.