Astronomy – The Study of Celestial Objects and Phenomena

Astronomy is the study of celestial objects and phenomena – stars, planets, comets, asteroids, galaxies and more – outside the Earth’s atmosphere. It’s also concerned with the large-scale properties of the Universe, sometimes called “The Big Picture”. It includes the physics of the celestial objects and their environments as well as their chemistry and history. Astronomy can be considered as a branch of science, but it is also a discipline of human curiosity and imagination.

The first astronomical observations were made using the naked eye, but with the advent of the telescope in the 17th century, it became possible to build a catalog of celestial objects, including their positions and movements, and even to determine the dimensions and masses of some of them. This work was important for calendrical, astrological and navigational purposes as well as scientific discovery.

It was also at this time that astronomers began to realize that the position of celestial objects could be explained by their laws of motion and gravity, rather than simply a combination of chance and luck. This led to a revolution in astronomy that has continued to this day, with the use of increasingly sophisticated instruments and techniques, such as the development of spectroscopy (which allows astronomers to study the chemical composition of celestial bodies) and radioastronomy.

In the second half of the 19th century, astronomers discovered how to observe light from distant objects without its being scattered by the atmosphere of the Earth. This opened the door to a whole new range of astronomical investigations, such as studying the chemical composition of celestial bodies, starting with those close to the Earth, then moving on to the more distant ones, including other stars and galaxies. It also allowed the investigation of a completely new class of phenomenon, such as pulsars which send regular pulses of radio waves out into space.

Today, astronomers are concerned with the study of everything from the soil composition on Mars to the ultimate fate of the Universe itself. They do this with the aid of increasingly powerful and sophisticated telescopes, both on the ground and in space.

Some astronomers specialise in particular areas, for example, the study of stars or the formation and structure of galaxy clusters. Others, known as theoretical astronomers, attempt to create models of celestial objects and their behaviour based on existing observational data. These models are then tested by observing the predicted effects of those models, for instance the rotation rate of stars or the distribution of matter in galaxy clusters. If a model is found to be inconsistent with observed facts, it may be rejected. The same process can be used to modify models that have already been established. Astronomers are also involved in developing cosmological models that attempt to explain the evolution of the Universe from its early stages. The most serious amateur astronomers actively participate in this research.