We often hear of famous astronomers and astrophysicists that astound us with their discoveries, but what is the difference between the two? Both are natural sciences involving the study of celestial bodies. The media sectors often use these terms interchangeably, which adds to the confusion. However, astronomy is not synonymous with astrophysics. To understand the differences between these two terms, we need to consider the history, astronomers and their contributions to the discipline, and any other relevant facts that clearly prove uniqueness, in each.
Astronomy is a science that not only focuses on the study of celestial bodies, but also on their movement, surroundings, effects on other events; also natural phenomena – and anomalies – in space. There are, generally, two major categories of astronomy: theoretical and observational. Theoretical astronomy describes the use, development, and construction of theoretical models of the universe, including its properties and contents. Theoretical astronomers either develop existing models, or create new models based on imagination and theoretical knowledge. Observational astronomy is the use of data from research equipment, such as telescopes and spectrometers, to create models.
It is widely accepted that astronomy, as a science, started with Nicolaus Copernicus. Although there were many before him that observed the sun, moon, stars and nearby planets, attempting to make logical assumptions of the existence, properties, and movement of these heavenly bodies. However, many of these ancient concepts have been discarded due to their inaccurate, or obsolete, nature. In 1543, just before his death, Copernicus’s book De revolutionibus orbium coelestium – On the Revolutions of the Celestial Spheres – revolutionized science. It explained that the Sun was at the center of the Solar System, rather than the Earth as previously believed, and that planetary bodies revolve around the Sun.
Contrary to astronomy, astrophysics is a science that exclusively focuses on celestial bodies, properties and movement. Astrophysics is a branch of astronomy which does not consider other natural phenomena and anomalies in space. According to the National Aeronautics and Space Administration (NASA), the goals of astrophysicists are to explore how the universe began, how it evolved, and how it works by studying planets and stars.
Astrophysics, as a branch of astronomy, began with Isaac Newton, whose concepts we have often utilized during our Physics tuition classes. Before Newton, scientists relied on mathematics alone to explain the properties of celestial bodies. Newton’s introduction of concepts related to the physical world changed the way scientists thought of all planetary bodies – his law of universal gravitation resulted in major breakthroughs in the fields of space sciences.