TFNR - Cosmic objects and bodies
In the common use, in astronomy, the two terms object and body are often used indifferently. Astronomical or celestial bodies are single, compact physical entities. Astronomical object are complex, more structured physical entities, which can consist of many parts, objects, bodies.
While Cosmic structures define more complex, structured and wide arrangements / organizations of interrelated parts, objects and bodies. Bodies and objects represent the components that make up the complex cosmic structures that fill the Universe.
In any case, let's give some examples of the objects, bodies that populate the cosmos:
- small aggregates of dust and frozen substances
- small to medium rocks
- asteroids
- comets with their tails
- moons and satellites
- planetoids
- planets
- stars of various types and in different phases of their evolution (various populations and evolutive paths)
- planetary systems
- star clusters and filaments
- nebulae
- galaxies
Planetary systems, star clusters, nebulae, galaxies as well as objects can be considered astronomical structures, bridges between stellar bodies and their planetary systems and large cosmic structures (groups and clusters of galaxies, superclusters, the cosmic web, etc.).
Let's examine in greater detail galaxies, the most complex and vast objects that we have listed here.
Galaxies
Galaxies can have various extensions (dwarf, normal size, extralarge) and shapes: regular (spiro, elliptical), irregular (colliding / merging galaxies), strange shaped galaxies, etc.
These highly structured objects are more than collections, aggregates of gas, dust, rocks, stars, planets, etc. In fact, their visible part, made up of ordinary matter and radiation, represents only a small part of these cosmic objects. The most extensive, massive and relevant part for its overall structure and dynamics is what we call dark.
Links to the tables of contents of TFNR Paper
