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). Astronomy also intersects with biology, as astrobiology, studying potential life throughout the universe.

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 natural science – one that seeks to elucidate the rules that govern the natural world using empirical and scientific methods.
    • A branch or field of space science
• 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.^[1][2] 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.
  • Quantum cosmology - the study of cosmology through the use of quantum field theory to explain phenomena general relativity cannot due to limitations in its framework.
  • 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.
  • Atmospheric science – study of atmospheres and weather.
  • Exoplanetology – various planets outside of the Solar System
  • Planetary formation – formation of planets and moons in the context of the formation and evolution of the Solar System.
  • Planetary rings – dynamics, stability, and composition of planetary rings
  • Magnetospheres – magnetic fields of planets and moons
  • Planetary surfaces – surface geology of planets and moons
  • Planetary interiors – interior composition of planets and moons
  • Small Solar System bodies – smallest bodies, including asteroids, comets, Kuiper belt objects, and dust.
• 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, specifically the ranges of wavelengths observed:
    • Radio astronomy – Above 300 μm
    • Submillimetre astronomy – 200 μm to 1 mm
    • Infrared astronomy – 0.7–350 μm
    • Optical astronomy – 380–750 nm
    • Ultraviolet astronomy – 10–320 nm
    • X-ray astronomy – 0.01–10 nm
    • Gamma-ray astronomy – Below 0.01 nm
    • Cosmic ray astronomy – Cosmic rays, including plasma
    • Neutrino astronomy – Neutrinos
    • Dust astronomy – Cosmic dust
    • Gravitational wave astronomy – Gravitons
  • 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:
  • Archaeoastronomy
  • Astrochemistry

History of astronomy

Basic astronomical phenomena

Astronomical objects

Astronomical object

Solar System

• Solar System
• Geology of solar terrestrial planets
• List of Solar System objects
  • List of Solar System objects by size
• Galilean satellites
• Halley's comet

Sun

Planets

Small Solar System bodies

Exoplanets

• Exoplanet (also known as extrasolar planets) – planet outside the Solar System. A total of 4,341 such planets have been identified as of 28 Jan 2021.
  • Super-Earth – exoplanet with a mass higher than Earth's, but substantially below those of the Solar System's ice giants.
  • Mini-Neptune – also known as a gas dwarf or transitional planet. A planet up to 10 Earth masses, but less massive than Uranus and Neptune.
  • Super-Jupiter – an exoplanet more massive than Jupiter.
  • Sub-Earth – an exoplanet "substantially less massive" than Earth and Venus.
  • Circumbinary planet – an exoplanet that orbits two stars.
  • Hot Jupiter – an exoplanet whose characteristics are similar to Jupiter, but that have high surface temperatures because they orbit very close to their parent stars, whereas Jupiter orbits its parent star (the Sun) at 5.2 AU (780×106 km), causing low surface temperatures.
  • Hot Neptune – an exoplanet in an orbit close to its star (normally less than one astronomical unit away), with a mass similar to that of Uranus or Neptune.
  • Pulsar planet – a planet that orbits a pulsar or a rapidly rotating neutron star.
  • Rogue planet (also known as an interstellar planet) – a planetary-mass object that orbits the galaxy directly.

Stars and stellar objects

• Fixed stars

Stars

Variable stars

Supernovae

Black holes

Constellations

• Constellation

The 88 modern constellations

Constellation history

The 48 constellations listed by Ptolemy after 150 AD

The 41 additional constellations added in the 16th and 17th centuries

Obsolete constellations including Ptolemy's Argo Navis

Clusters and nebulae

Galaxies

• Galaxy
• Andromeda Galaxy
• Magellanic Clouds
• Quasar

Cosmology

Space exploration

See: Outline of space exploration

Organizations

Public sector space agencies

Space agencies

Africa

North Africa

•  Algerian Space Agency
•  National Authority for Remote Sensing and Space Sciences
• Egypt Remote Sensing Center
•  Royal Centre for Remote Sensing
•  National Remote Sensing Center

Sub-Saharan

•  National Space Research and Development Agency
•  South African National Space Agency

North America

•  Agencia Espacial Mexicana
•  Canadian Space Agency
•  NASA
•  United States Department of Defense
  • National Reconnaissance Office
  • United States Army Space and Missile Defense Command
  • United States Space Command
  • United States Space Force

South America

•  Agencia Bolivariana para Actividades Espaciales
•  Brazilian Space Agency
•  Brazilian General Command for Aerospace Technology
•  Colombian Space Commission
•  Comisión Nacional de Actividades Espaciales
•  Comisión Nacional de Investigación y Desarrollo Aeroespacial
•  Instituto Tecnológico de Aeronáutica
•  Instituto Venezolano de Investigaciones Científicas
•  National Institute for Space Research

Asia

East Asia

•  China Aerospace Science and Technology Corporation (China Academy of Launch Vehicle Technology
• China Academy of Space Technology
• China Chang Feng
• China Aerospace Science and Technology Corporation
• Commission for Science, Technology and Industry for National Defense)
• China National Space Administration
•  Japan Aerospace Exploration Agency (Institute of Space and Astronautical Science
• National Aerospace Laboratory of Japan
• National Space Development Agency of Japan)
• National Institute of Information and Communications Technology
• Institute for Unmanned Space Experiment Free Flyer
•  National Remote Sensing Center
•  Korean Committee of Space Technology
•  Korea Aerospace Research Institute
•  National Space Organization

Southeast Asia

•  National Institute of Aeronautics and Space
•  Malaysian Space Agency
•  Philippine Atmospheric, Geophysical and Astronomical Services Administration
•  Thai Ministry of Science and Technology's Space Agency
•  Space Technology Institute
• Vietnam Space Commission

South Asia

•  Space Research and Remote Sensing Organization
•  Department of Space
  • Antrix Corporation
  • Indian Institute of Space Science and Technology
  • Indian Space Research Organisation
  • National Atmospheric Research Laboratory
  • New Space India Limited
  • North-Eastern Space Applications Centre
  • Physical Research Laboratory
  • Semi-Conductor Laboratory
•  Space and Upper Atmosphere Research Commission

Southwest Asia

•  Azerbaijan National Aerospace Agency¹
•  Iran Aviation Industries Organization
• Iranian Space Agency
•  Israel Space Agency
• National Committee for Space Research
•  TÜBİTAK UZAY

Central Asia

•  KazCosmos
• Kazakh Space Research Institute¹
•  Turkmenistan National Space Agency¹
•  UzbekCosmos¹

Europe

•  Austrian Space Agency
•  Belarus Space Agency¹
•  Belgian Institute for Space Aeronomy
•  Bulgarian Space Agency
•  Czech Space Office
•  Danish National Space Center
• esa European Cooperation for Space Standardization
• European Space Agency
•  EUMETSAT
• European Union Satellite Centre
•  CNES
•  German Aerospace Center
•  Institute for Space Applications and Remote Sensing
•  Hungarian Space Office
•  Space Ireland
•  Italian Space Agency
•  Space Science and Technology Institute¹
•  Luxinnovation
•  Netherlands Institute for Space Research
•  Norwegian Space Centre
•  Space Research Centre
•  Portuguese Space Company
•  Romanian Space Agency
•  Russian Federal Space Agency¹
• Russian Space Research Institute¹
• Russian Space Forces
•  Soviet space program
•  Instituto Nacional de Técnica Aeroespacial
•  Swedish National Space Board
•  Swiss Space Office
•  UK Space Agency
•  State Space Agency of Ukraine¹

Oceania

•  Commonwealth Scientific and Industrial Research Organisation

World

• Asia-Pacific Space Cooperation Organization
• Consultative Committee for Space Data Systems
•  Committee on Space Research
• International Academy of Astronautics
• International Telecommunications Satellite Organization
• Intercosmos
• Intersputnik
•  Pan-Arab Space Agency
•  United Nations
  • United Nations Committee on the Peaceful Uses of Outer Space
  • United Nations Office for Outer Space Affairs

¹ Preceded by the Soviet space program

Books and publications

Astronomers