Solar system

We explain what the solar system is and what its characteristics are. How is it formed, and what are the solar system’s planets?

What is the solar system?

The solar system is the planetary context in which our planet Earth is located: a circuit where eight planets constantly orbit a single star, the Sun.

Of course, ours is not the only planetary system that exists. There are systems of dynamic forces around the gravity of one or more stars throughout the galaxy and the universe, so it is relatively safe to assume that there are valuable systems.

Our solar system is part of the Local Interstellar Cloud within the Local Bubble of Orion’s arm, located about 28,000 light-years from the bright centre of our galaxy, the Milky Way. It is estimated that it was formed 4568 million years ago due to the collapse of a molecular cloud, giving rise to a circumstellar or protoplanetary disk, that is, a disorderly set of matter surrounding the Sun in the form of rings. From there, our space neighbourhood’s different planets and astronomical objects would have been constituted.

The objects of the Solar System, as in other planetary systems, remain in an elliptical orbit around the most prominent star, with the most extraordinary gravity in the system. In our case, of course, it is the Sun, a G-type star with a total diameter of 1,392,000 kilometres, which contains 99.86% of the solar system’s total mass.

How is the solar system formed?

As has been said, in the very centre of the solar system is the Sun, a yellow dwarf star of luminosity V, and the only star that emits its light in the group. Eight planets of different sizes and at different distances orbit around it, tracing elliptical paths as they go.

Similarly, there is a fertile field of asteroids in a belt after Mars and a much larger one after Neptune. In addition, asteroids exist in the rings surrounding giant outer planets such as Saturn and Uranus.

Natural satellites should also be mentioned, such as our Moon or the moons of Mars: Deimos and Phobos, which are abundant in the outer planets: Jupiter and Saturn have 63 and 61, respectively, while Neptune and Uranus have 27 and 13.

Finally, there is a series of trans-Neptunian objects, the furthest from the Sun in the system, whose little impact from sunlight makes it difficult to study, but which hypothetically would be three:

  • The Kuiper Belt. A tangle of celestial bodies that orbit distantly from the Sun, among which the short-period comets that visit us from time to time could be born. Pluto and its satellite Charon are considered the most significant objects in this group.
  • The Scattered Disc. A region of space overlapping the Kuiper Belt and extending to an unknown distance away from the Sun. There would be an uncertain number of astronomical objects, estimated to be around 90.
  • The Oort Cloud. A spherical cloud of celestial bodies, located almost a light year from the Sun, a hundred times further than the Kuiper
  • Belt. It is assumed that there would be between one and one hundred billion objects, which add up to a total mass five times greater than Earth’s.

solar system planets

There are eight major planets in the solar system, divided into two groups:

Inner planets. The closest to the Sun and the smallest: are Mercury, Venus, Earth and Mars. They are also called terrestrial or telluric planets since they have a solid, concrete surface around which there is an atmosphere (except in the case of Mercury).
Outer planets. After the asteroid belt in the middle of the planetary system, gigantic and gaseous: Jupiter, Saturn, Neptune and Uranus. The last two are known as the frost giants.

There is also a set of dwarf planets, including Pluto since 2006: Ceres, Makemake, Eris and Haumea. They have enough mass to form a spherical shape but not enough to attract or repel surrounding objects, so they are intermediate between planets and asteroids.

Recent studies indicate that there could be a ninth planet, provisionally called Pattie, but nothing has yet been confirmed.

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