Physics – Astrophysics – Astronomy
Let’s start by defining these three terms:
Physics – science concerned with the laws that govern the structure of the universe, and the forms of matter and energy.
Astronomy – astronomy is primarily an observational science concerned with the motions, positions, distances, distributions, and physical conditions of celestial objects
Astrophysics – the study of physical properties and composition of celestial objects using the known laws of physics. In the simplest sense, astrophysics is physics + astronomy.
It began with the development of spectroscopy in the 19th century, which allowed astronomers to analyze composition of stars from their light. Astrophysics view the universe as a vast natural laboratory in which they can study matter under conditions of temperature, pressure, and density that are not unattainable on Earth.
I wanted to take astronomy as a major when I get to college, but since astronomy wasn’t offered in schools I knew, I took the closest thing – Physics. I could remember swiftly passing through astronomy topics in our general science in high-school, and not reaching astro topics in our high-school physics. This made me crave for more knowledge on astronomy since I was really interested. I could even remember taking my fourth year classmates to the physics department and encouraging them to take the course with me.
Taking physics as a major, I get introduced to various concepts and topics covered by physics. Most of the topics or fields we cover are actually used in astrophysics and astronomy. Like physics, astronomy covers essentially the same thing, only with focus outside our planet. If you were not really interested, you wouldn’t see the strong connection between physics and astronomy: how optics and radiation are the strongest tools in measuring and observing the celestial, how matter and gravity affect everything, how temperature and luminosity describe to us the nature of stars, how nuclear energy give power to the stars and galaxies, how relativity makes us understand black holes, how particle physics tells us where all the matter in the universe comes from, how practically most of the knowledge we have on astronomy is defined by the laws of physics
As of now, I am an amateur astronomer who is still getting in the hang of knowing the wonders of the night sky. I wasn’t a first-section student in high-school and I’m not that fast with math. But, being a physics major does help me understand the concepts I encounter in my further readings.
How the science of physics and astronomy is intertwined really fascinates me.