At a quick glance at the starry sky, the planets are practically indistinguishable from the stars, however, the planets visible to the naked eye are very bright stars and, therefore, their location is relatively easy when you know where to look for them. The planets are easy to distinguish because their light almost does not twinkle, unlike starlight, and they are always in the plane of the elliptical, which is the imaginary line along which the Sun, the Moon, the planets apparently move. and the zodiacal constellations across the firmament. If the stars are always seen as points of light (even with the largest telescope), the planets are at such a short distance from us that we see them as small disks, moving between them (hence their name, from the Greek: planet = wanderer, wandering star) at a speed that depends on its distance from the Sun.
Thus, the planets Those closest to it move faster than those further away: for example, Mercury moves at 47.87 km/s (taking 88 Earth days to complete a complete revolution around the Sun), while Pluto does so at about 4.74 km/s (taking about 248 Earth years). The planets are classified as internal (Mercury, Venus, Earth, Mars) and external (Jupiter, Saturn, Uranus, Neptune); In another widely known classification, the planets are also divided into rocky (Mercury, Venus, Earth, Mars) and gaseous (Jupiter, Saturn, Uranus, Neptune). Finally, the most recent classification regarding the objects of the Solar System is that of dwarf planet, a category in which Pluto is found today, as well as Ceres (the largest object in the Main Asteroid Belt), Eris, Makemake and Haumea.
Below are some outstanding qualities of planets and dwarf planets in the Solar System.
1. With the exception of Pluto (today a dwarf planet), all the planets describe their orbit in planes very close to the ecliptic.
2. With the exception of Uranus and Venus, all the planets rotate around their axis in the same direction and most of the satellites rotate in the same direction as their respective planets with the exception of six, including Triton, of Neptune.
3. 99% of the Solar System's mass is in the Sun; However, it only has 1/30 of the angular momentum. Jupiter, with 0.1% of mass, occupies 59% of angular momentum.
4. Saturn's rings rotate faster than the planet's rotational motion.
5. The separation of the planes grows approximately according to a geometric progression, taking the Sun as a reference point. This, the Titius-Bode law, is generally fulfilled, but with very strong errors in Neptune and Pluto, and with a gap in the area currently known as the Main Asteroid Belt between Mars and Jupiter.
6. The planets of the Solar System are divided into rocky and giant. The former are solid spheres with a density greater than that of water and their chemical components have a high atomic weight. These planets rotate very slowly and have few or no satellites.
7. Giant planets have diameters much larger than rocky planets. Its composition is gaseous and liquid, due to the low atomic weight elements that compose it. Its density is small, being barely higher than that of water (except Saturn). Their extensive atmospheres contain light elements such as hydrogen and helium, methane and ammonia. They rotate quickly and have many satellites around them.
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