Branches of Astronomy

Study Notes

Astrophysics: study of the physical nature of celestial objects and phenomena
Planetary Science: study of planets, moons, asteroids, comets, and other objects in our solar system
Cosmology: study of the origin, evolution, and fate of the universe

Stars: massive, luminous balls of gas that are sustained by nuclear reactions in their cores
Galaxies: massive, gravitationally bound systems consisting of stars, stellar remnants, interstellar gas, dust, and dark matter
Planets: large, rocky or gaseous bodies that orbit around stars
Moons: natural satellites that orbit around planets
Asteroids: small, rocky objects that orbit around the Sun
Comets: icy bodies that release gas and dust as they approach the Sun

Light-year: unit of distance, equivalent to the distance light travels in one year (9.46 trillion km)
Parsec: unit of distance, equivalent to 3.26 light-years
Astronomical Unit (AU): average distance between the Earth and the Sun (149.6 million km)

Reflector Telescopes: use mirrors to collect and focus light
Refractor Telescopes: use lenses to collect and focus light
Radio Telescopes: use radio waves to detect celestial objects
Space Telescopes: telescopes that orbit around the Earth, such as the Hubble Space Telescope
Spectroscopy: study of the interaction between matter and electromagnetic radiation

Eclipses: phenomena in which one celestial object passes into the shadow of another
Supernovae: extremely powerful explosions that occur when a star runs out of fuel
Black Holes: regions of spacetime where gravity is so strong that not even light can escape
Gravitational Waves: ripples in spacetime that are produced by massive, accelerating objects

Astrophysics studies the physical nature of celestial objects and phenomena.
Planetary Science focuses on planets, moons, asteroids, comets, and other objects in our solar system.
Cosmology explores the origin, evolution, and fate of the universe.

Stars are massive, luminous balls of gas sustained by nuclear reactions in their cores.
Galaxies are massive, gravitationally bound systems consisting of stars, stellar remnants, interstellar gas, dust, and dark matter.
Planets are large, rocky or gaseous bodies that orbit around stars.
Moons are natural satellites that orbit around planets.
Asteroids are small, rocky objects that orbit around the Sun.
Comets are icy bodies that release gas and dust as they approach the Sun.

A light-year is a unit of distance, equivalent to 9.46 trillion km.
A parsec is equivalent to 3.26 light-years.
An Astronomical Unit (AU) is the average distance between the Earth and the Sun, equivalent to 149.6 million km.

Reflector Telescopes use mirrors to collect and focus light.
Refractor Telescopes use lenses to collect and focus light.
Radio Telescopes use radio waves to detect celestial objects.
Space Telescopes, such as the Hubble Space Telescope, orbit around the Earth to observe celestial objects.
Spectroscopy is the study of the interaction between matter and electromagnetic radiation.

Eclipses occur when one celestial object passes into the shadow of another.
Supernovae are extremely powerful explosions that occur when a star runs out of fuel.
Black Holes are regions of spacetime where gravity is so strong that not even light can escape.
Gravitational Waves are ripples in spacetime produced by massive, accelerating objects.