Romobjekter

Romobjekter, often translated as "space objects" or "celestial bodies," refers to any naturally occurring entity that exists in outer space. This broad category encompasses a vast array of astronomical phenomena. The most familiar romobjekter are planets, large celestial bodies that orbit a star and have cleared their orbital path of other debris. Moons, also known as natural satellites, are smaller bodies that orbit planets. Stars themselves are massive, luminous spheres of plasma held together by their own gravity, generating light and heat through nuclear fusion.

Beyond planets and stars, the universe is populated by numerous other romobjekter. Asteroids are rocky, airless worlds that orbit the Sun, many of which are found in the asteroid belt between Mars and Jupiter. Comets are icy bodies that, when close to the Sun, display a visible coma (atmosphere) and sometimes a tail. Dwarf planets are celestial bodies that orbit the Sun, are massive enough for their own gravity to make them round, but have not cleared their orbital neighborhood of debris.

Further out in space are nebulae, which are clouds of gas and dust, often the birthplaces of stars. Galaxies are immense collections of stars, stellar remnants, interstellar gas, dust, and dark matter, all bound together by gravity. Even smaller particles, such as meteoroids, are considered romobjekter, becoming meteors when they enter Earth's atmosphere and meteorites if they survive the passage and land on the surface. Understanding these diverse romobjekter is fundamental to comprehending the structure and evolution of the cosmos.