Planeetidele

Planeetidele is a general term in Estonian referring to planets. In astronomy, planets are celestial bodies that orbit a star, are massive enough to be rounded by their own gravity, and have cleared the neighborhood around their orbit. The Solar System, for example, has eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. The definition of a planet has evolved over time, notably with the reclassification of Pluto in 2006 as a dwarf planet.

The study of planets, known as planetary science, is a multidisciplinary field that draws on astronomy, geology, physics, and chemistry. Scientists investigate the formation, evolution, and composition of planets both within our solar system and in exoplanetary systems around other stars. Exoplanets, or planets outside our solar system, are a significant area of current research, with thousands having been discovered using various detection methods.

The characteristics of planets vary widely. Rocky planets, like those in the inner solar system, have solid surfaces. Gas giants, such as Jupiter and Saturn, are composed primarily of hydrogen and helium and lack a defined surface. Ice giants, like Uranus and Neptune, have a higher proportion of "ices" such as water, ammonia, and methane. Understanding these differences helps us comprehend the diversity of planetary formation and the potential for habitability on other worlds. The exploration of planets, both through telescopes and robotic missions, continues to expand our knowledge of the cosmos.