planeter

Planeter is the plural form of planet in several European languages, and in astronomy it designates large celestial bodies that orbit a star. By the standard criteria used by the International Astronomical Union, a planet is a body that 1) orbits a star, 2) has sufficient mass for self-gravity to shape it into a nearly round form, and 3) has cleared other debris from its orbital zone. In our Solar System, eight planets are recognized: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Pluto was reclassified in 2006 as a dwarf planet. Planeter also exist around other stars, where they are called exoplanets.

Planeter show a wide range of sizes, compositions, and distances from their stars. They are typically divided into terrestrial planets, which are rocky and relatively small (for example, Mercury, Venus, Earth, and Mars), and giant planets, which are much larger and can be gas giants (Jupiter and Saturn) or ice giants (Uranus and Neptune). Planeter form in protoplanetary disks around young stars, through the accumulation of dust and gas that eventually builds up planetary bodies. The process can lead to diverse planetary systems with a variety of orbital configurations.

Observation and study of planeter rely on several methods. Indirect techniques include the radial-velocity method and transit observations, while direct imaging and gravitational microlensing can reveal some planets directly. Space missions such as Kepler and TESS have discovered thousands of exoplanets, greatly expanding knowledge of planetary systems. Spectroscopic analysis during transits or eclipses enables the study of some planetary atmospheres.

Planeter are central to questions about planetary formation, dynamics, and the potential for life beyond Earth. The habitable zone around a star outlines where liquid water might persist on a planet’s surface, guiding investigations into astrobiology and the diversity of planetary environments.