Astronomy vs Astrophysics [What Are The Main Differences?]

Astronomy and Astrophysics are closely aligned and in many ways it is hard to distinguish between them. Despite their close ties, there are distinctions which will be the purpose of this article today.

So, what is the major distinction between Astronomy vs Astrophysics? In theory, Astronomy is the study of the universe beyond the earth’s atmosphere measuring the positions and characteristics of celestial objects. While Astrophysics is considered a branch and subset of Astronomy that applies the principles of physics to understand Astronomy. The detachment of the two fields is mainly historical and/or linguistic. 

The distinction between Astronomy and Astrophysics has become more and more ambiguous over the last century.

Academically speaking, a lot of university courses can overlap between the fields: a graduate “Astronomer” from one university may have followed a similar education path and training as an “Astrophysicist” from a separate university. In this way the terms are often conflicted or used interchangeably.

However, from a purely practical stance, Astronomy is the general study of celestial objects whereas Astrophysics studies how these objects are actually composed, exist and evolve.

So here’s a few examples; an Astrophysicist may analyse how a star changes over a period of time, how a galaxy evolves as an independent structure, or how nebulae interacts with other celestial objects.

Astronomy vs Astrophysics

Nowadays, the two terms are often confused or used interchangeably as Astronomers often use physics to understand their findings. Nonetheless, there is a distinction as we will outline below:

Astronomy is the scientific pursuit of studying the universe and all objects that fall outside of the earth’s own atmosphere.

Astrophysics is considered a subset/branch of astronomy that focuses on the physical processes of celestial objects and their respective regions in time and space. It focuses primarily on the compositions, energy systems, and the calculations behind the evolution of the universe.

So, if you think of it differently, Astronomy is like the overall top level science that focuses on any scientific pursuit of space beyond and outside of our atmosphere. Astrophysics focuses entirely on the actual physics of stars, planets, galaxies, black-holes, their formation, evolution and ultimately their future.

Whats The Difference Between an Astronomer and an Astrophysicist?

We can help to understand the differences between the fields by looking at the respective outlooks and pursuits of the individuals who pursue each field.

An Astronomer uses a telescope, or other astronomical instrument (e.g. binoculars) to observe the night sky, make star charts and learn about the solar system.

An Astrophysicist would compile, review and conduct equations and calculations on the various celestial objects in the sky.

For example, they may try to calculate how big a star has to be before it becomes a black hole.

The Astrophysicist is interested not only with the movements of stars, but their composition and properties – temperature, chemical and metallic composition, density, luminosity etc.

In other words and metaphorically speaking, the astronomer studies the car by observing it’s speed, size, and all of its various movements.

The astrophysicist studies that same car by taking it apart down to the point of determining the properties of its gears/tires etc.

Simply speaking, any astronomer whose initial interest transitions from observation to scientific analysis is making the transition from astronomy to astrophysics.