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17 Branches of Astronomy

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Branches of Astronomy

Astronomy is the study of celestial objects and phenomena. It is the all-encompassing term that studies everything beyond Earth’s atmosphere. It applies the concepts from physics, biology, and geology to explain their origin and evolution.

We can divide astronomy into 4 sub-fields:

  • ASTROPHYSICS: Applying the laws of physics in space
  • ASTROMETRY: Mapping celestial bodies
  • ASTROGEOLOGY: Examining rocks, terrain and material in space
  • ASTROBIOLOGY: Searching for life outside Earth

And we can categorize into 17 branches of astronomy.


Earth Universe

Astrophysics applies the principles of physics to astronomy. Akin with geophysics which studies Earth’s physics, astrophysics relates physical processes and properties to stars, celestial bodies, and its surrounding space.

Cosmology is different from astrophysics because it studies the evolution and expansion of the universe. For example, cosmologists study red-shift to see how fast the universe is expanding.

Spectroscopy studies how light reflects, absorbs, and transfers between matter. In a similar manner, photometry examines how luminous astronomical objects are in space based on electromagnetic radiation properties.

Asteroseismology is closely related to helioseismology. They both study the internal structure of stars by measuring radiation and oscillations. But helioseismology is specific to our sun.

Finally, heliophysics studies the sun’s constant and dynamic radiation that affects its surroundings in space. There have been various heliophysics missions to study space weather, solar flares, and the constant stream of solar particles from the sun.

  • ASTROPHYSICS – How the laws of physics apply to stars and celestial bodies.
  • COSMOLOGY – How the universe was created, evolves and its ultimate fate.
  • SPECTROSCOPY – How light reflects, absorbs and transfers between matter.
  • PHOTOMETRY – How luminous astronomical objects are in space based on electromagnetic radiation.
  • HELIOPHYSICS – How the sun’s constant and dynamic radiation affects its surroundings in space.
  • HELIOSEISMOLOGY – How the interior structure and dynamics of stars are composed by observing waves from its surface.
  • ASTEROSEISMOLOGY – How to study the internal structure of stars from observing their oscillations.


Milky Way Galaxy Alpha Centauri

Instead of the physics that drives motion in space, astrometry focuses on the precise position of celestial bodies. It also provides a frame of reference for the movement of stars and individual objects in space.

On a similar note, exoplanetology inventories how many and where planets exist outside of our solar system. This inventory of planets lists all potential residences for new life outside of Earth

Planetary science (planetology) is concerned with how planets form in the solar system including their composition and dynamics in history. This subject is tied closely to planetary geology.

  • ASTROMETRY – How celestial bodies are positioned and move in space.
  • PLANETOLOGY – How planets form in the solar systems including their composition and dynamics in history.
  • EXOPLANETOLOGY – How many and where planets exist outside our solar system.


Mars Rover

When the Mars Rover started wheeling around the red planet, its crosshairs were targeting the rocks and geology of Mars. Specifically, it was getting a close-up of the composition or areology of Mars.

READ MORE: 15 Facts About Mars: The Remarkable Red Planet [Infographic]

Astrogeology is very closely related to exogeology. They both focus on how geology relates to celestial bodies like moons, asteroids, meteorites, and comets.

Lastly, selenography studies the physical features of the moon. For example, it understands and catalogs features such as lunar maria, craters, and mountain ranges on the moon.

  • ASTROGEOLOGY – How geology relates to celestial bodies like moons, asteroids, meteorites and comets.
  • AREOLOGY – How geology is composed on Mars.
  • SELENOGRAPHY – How physical features on the moon formed such as lunar maria, craters and mountain ranges.
  • EXOGEOLOGY – How geology relates to celestial bodies like moons, asteroids, meteorites and comets.


Goldilocks Zone

Astrobiology involves the search for life outside Earth. It also asks the questions: What is the origin and evolution of life? Is there life on other planets? Which environments can support life?

If you want to measure the probability of life in space, exobiology considers planetary conditions for life. For example, exobiology also understands the early evolution of life and the biological/environmental factors to advance life.

Lastly, astrobiology pulls from astrochemistry to better understand substances in celestial bodies, stars, and interstellar space. Observing molecules in space gives a solid indication of the physical conditions to what we are used to on present-day Earth.

  • ASTROBIOLOGY -How life (including extraterrestrials) in the universe evolved, originated and what will be its fate.
  • EXOBIOLOGY – How likely and where is life in space.
  • ASTROCHEMISTRY – How to study substances in celestial bodies, stars and interstellar space.

Other Resources

1. NASA Astrophysics

nasa astrophysics

The NASA Astrophysics division finds our place in the universe. Specifically, it studies everything from dark energy, dark matter, black holes, the Big Bang, types of galaxies, stars and exoplanets.

Find out more on the official NASA astrophysics website.

2. The searchable astronomical database


The searchable astronomical database helps you orientate in the sky. It assists in organizing and making searchable all the world’s astronomical information. First, you submit an image of the sky. Next, it will return known objects that fall inside the view.

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