Scientist shows the maximum number of planets that can orbit the Sun

Our solar system has an unusually large number of planets compared to other known planetary systems.

In total, there are about 812 known planetary systems, each with three or more confirmed planets, and only one known planetary system with as many planets as our Solar System, Kepler-90. encyclopediaPlanets outside the solar system“.

From this we can see that our solar system is the most densely populated system with its eight planets, although the smaller inner planets have not yet been discovered in these outer planetary systems. But is this the maximum number of planets that can orbit the Sun, or is there room for more?

According to the science website “Live Science,” to calculate the absolute maximum number of planets that can orbit the Sun, we have to go into the theoretical world and ignore some natural factors that limit the number of planets that can form. . One of the best ways to do this is to design or engineer an entirely new solar system from scratch.

Sean Raymond, an astronomer specializing in planetary systems at the Bordeaux Astrophysical Observatory in France, has already done this. He designed what he called the “Ultimate Engineering Solar System” in which the number of planets was determined according to a few key variables.

1- Factors affecting the number of planets

Sean Raymond tells Live Science that the structure of a planetary system is the result of many complex factors, such as the size of the star, the size of the planets, whether they are rocky or gas giants, and the number. The moons orbiting each planet, the location of large asteroids and comets, those in the asteroid belt between Jupiter and Mars and the Kuiper Belt beyond Neptune, as well as the direction of the planets’ orbits and the amount of remaining material from the Sun or star to form the planets. It takes hundreds of millions of years of intense collisions and gravitational forces between planets for the system to settle into a stable configuration.

Raymond says that if we become a highly advanced civilization with technology and resources beyond our current capabilities, we will be able to overcome many limitations and design a solar system with a large number of planets.

2- The number of planets is defined by the number of orbits

In an engineered solar system, the maximum number of planets is limited by the number of planetary orbits you can put the Sun in a fixed configuration.

And when a planetary system becomes unstable, the planets’ orbits begin to intersect, collide, or become separated by gravity, and fly out of the system or orbit each other.

The minimum safe distance between the orbits of different planets in a fixed system depends on the size of each planet, or more precisely its “hill radius”. The Hale radius on a planet is the distance between the planet and the edge of its sphere of influence, where low-mass objects such as the Moon orbiting Earth are affected by its gravitational pull.

More massive planets exert a stronger gravitational pull, meaning they have larger Hale radii. According to NASA, the distance between Earth and Mars is about 78.3 million km, which is seven times smaller than the distance between the orbits of Mars and Jupiter, which is about 550.7 million km.

For this reason, the number of orbits that fit into the solar system depends largely on the size of the planets. For example, Jupiter is 300 times larger than Earth, meaning the Hale radius is about 10 times larger. This means that 10 separate Earth orbits could fit in the same space as Jupiter’s current orbit. So to increase the number of planets in a system, we need to make those planets as small as possible.

On the other hand, the number of orbits can be increased through the idea of ​​”reverse orbits”. In the current solar system, all the planets orbit the Sun in the same direction because the planets formed from a large cloud of dust that orbited the Sun in the same direction. However, a well-designed solar system may have planets orbiting the Sun in opposite directions, known as “reverse orbits”. It can be used to increase the number of orbits.

If two planets orbit the Sun in opposite directions, the gravitational forces between them may weaken slightly, reducing the minimum safe distance between their orbits.

3- 42 planets in one orbit

Each orbit in the solar system is assumed to contain only one planet. But if we want to maximize the number of planets in our engineered solar system, we want to put as many planets in the same orbit as possible, if they are far enough away to be stable.

In a study published in Astrodynamics and Dynamical Astronomy in 2010, scientists determined the number of planets that could share an orbit, and found that 42 Earth-sized planets could share an orbit.

But, according to Raymond, the chances of these many planets naturally sharing an orbit are almost zero, because that would require all the planets to be the same size and form at the same time.

4- Maximum geometry solar system

Sean Raymond used his computer simulations to calculate the theoretical maximum number of planets our solar system could have, based on the above key variables, and published the results on his Planet Planet blog.

In his model, Raymond used equal-sized (Earth-sized) planets with opposite orbits. Also, Raymond’s engineering system extended from the Sun up to a thousand astronomical units (AU) instead of the current 100 AU. According to the European Space Agency, this can be further extended by the effect of the Sun’s gravity. The astronomical unit represents the average distance between the Sun and Earth’s orbit, which is about 150 million km.

If we take all this into account, our solar system can accommodate 57 orbits, each containing 42 planets, so the total number of planets is 2394 planets.

If planets one-tenth the size of Earth were used, our solar system would accommodate 121 orbits, each containing 89 planets, for a total of 10,769 planets. If the planets were one-hundredth the size of Earth, there could be 341 orbits with 193 planets each, for a total of 65,813 planets.