BRANCHES OF ASTRONOMY: What is Astronomy?
Astronomy is the all-encompassing term that studies everything outside of Earth’s atmosphere. Then, 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.
ASTROPHYSICS: Applying the laws of physics in space
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 expansion and evolution 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 affects its surroundings in space. There’s been various heliophysics missions to study space weather, solar flares and the constant stream of solar particles from the sun.
ASTROMETRY: Mapping celestial bodies in outer space
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 systems including their composition and dynamics in history. This subject is tied closely to planetary geology.
ASTROGEOLOGY: Examining rocks, terrain and material in space
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.
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 moon. For example, it understands and catalogs features such as lunar maria, craters and mountain ranges on the moon.
ASTROBIOLOGY: The search for life
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 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 to the physical conditions to what we are used to on present day Earth.