The following outline is provided as an overview of and topical guide to astronomy:
Astronomy – studies the universe beyond Earth, including its formation and development, and the evolution, physics, chemistry, meteorology, and motion of celestial objects (such as galaxies, planets, etc.) and phenomena that originate outside the atmosphere of Earth (such as the cosmic background radiation).
Nature of astronomy
Astronomy can be described as all the following:
- An academic discipline: one with academic departments, curricula and degrees; national and international societies; and specialized journals.
- A scientific field (a branch of science) – widely recognized category of specialized expertise within science, and typically embodies it
- A hobby or part-time pursuit for the satisfaction of personal curiosity or appreciation of beauty, the latter especially including astrophotography.
Branches of astronomy
- Astrobiology – studies the advent and evolution of biological systems in the universe.
- Astrophysics – branch of astronomy that deals with the physics of the universe, including the physical properties of celestial objects, as well as their interactions and behavior. Among the objects studied are galaxies, stars, planets, exoplanets, the interstellar medium and the cosmic microwave background; and the properties examined include luminosity, density, temperature, and chemical composition. The subdisciplines of theoretical astrophysics are:
- Compact objects – this subdiscipline studies very dense matter in white dwarfs and neutron stars and their effects on environments including accretion.
- Physical cosmology – origin and evolution of the universe as a whole. The study of cosmology is theoretical astrophysics at its largest scale.
- Computational astrophysics – The study of astrophysics using computational methods and tools to develop computational models.
- Galactic astronomy – deals with the structure and components of our galaxy and of other galaxies.
- High energy astrophysics – studies phenomena occurring at high energies including active galactic nuclei, supernovae, gamma-ray bursts, quasars, and shocks.
- Interstellar astrophysics – study of the interstellar medium, intergalactic medium and dust.
- Extragalactic astronomy – study of objects (mainly galaxies) outside our galaxy, including Galaxy formation and evolution.
- Stellar astronomy – concerned with Star formation, physical properties, main sequence life span, variability, stellar evolution and extinction.
- Plasma astrophysics – studies properties of plasma in outer space.
- Relativistic astrophysics – studies effects of special relativity and general relativity in astrophysical contexts including gravitational waves, gravitational lensing and black holes.
- Solar physics – Sun and its interaction with the remainder of the Solar System and interstellar space.
- Planetary Science – study of planets, moons, and planetary systems.
- Astronomy divided by general technique used for astronomical research:
- Astrometry – study of the position of objects in the sky and their changes of position. Defines the system of coordinates used and the kinematics of objects in our galaxy.
- Observational astronomy – practice of observing celestial objects by using telescopes and other astronomical apparatus. It is concerned with recording data. The subdisciplines of observational astronomy are generally made by the specifications of the detectors:
- Photometry – study of how bright celestial objects are when passed through different filters
- Spectroscopy – study of the spectra of astronomical objects
- Other disciplines that may be considered part of astronomy:
History of astronomy
Basic astronomical phenomena
Small Solar System bodies
- Extrasolar planet – planet outside the Solar System. A total of 899 such planets (in 698 planetary systems, including 133 multiple planetary systems) have been identified as of 27 June 2013.
Stars and stellar objects
Artist's representation of a black hole.
The 88 modern constellations
The 48 constellations listed by Ptolemy after 150 AD
The 41 additional constellations added in the 16th and 17th centuries
Clusters and nebulae
- See: Outline of space exploration
Public sector space agencies
1 Preceded by the Soviet space program
Books and publications