What is astronomy?
In short, introduction to astronomy is the study of the universe and everything in it. Planets, stars, comets, galaxies etc. all come under this bracket. The word “astronomy” comes from two Greek words – “astro”, meaning “star” and “nomos”, meaning “law”. Therefore, astronomy can be interpreted as the study of the universe and the laws which govern its actions. The official NASA definition is “the study of stars, planets and space”.
It’s easy to confuse this subject with astrology. In reality though, the two are poles apart. Astrology is the study of the stars and deducing people’s personal characteristics and futures based on the findings. It has no basis in scientific fact, unlike astronomy which relies heavily on hard facts and evidence.
This is one of the oldest sciences. Since the dawn of civilisation, humans have looked with wonderment at the night sky and the stars, planets and constellations it contains. The Ancient Greeks were among the earliest pioneers and, despite a lack of sophisticated equipment, they were able to achieve some impressive feats.
Among their accomplishments were the calculation of the size of the Sun and its distance from Earth. In the Middle Ages, the study of astronomy faltered in Europe but it prospered in places such as China, Persia and Arabia. It was not until the Renaissance period and the emergence of such notable scientists as Galileo and Newton that the study in Europe began to regain momentum.
The invention of the telescope by Hans Janssen was crucial in enabling astronomy to evolve into a major modern science. A significant recent advancement in the field came in 1990 with the launch of the Hubble Telescope, which continues to record and send back essential data as well as monumentally clear photos of stars and galaxies. Space probes and satellites, some launched decades ago, continue to explore the Solar System and transmit data and images billions of miles back to Earth.
The subject is divided into two main branches. The first of these is visible-light, or optical, astronomy. This branch focuses on observations which use telescopes and other instruments to capture visible light.
The downsides to earth-bound forms of this this type of astronomy are that the optical spectrum is relatively narrow and the Earth’s own atmosphere ether blocks out entirely or bounces off the light, thereby distorting any received images. Human factors such as light pollution also has a negative impact on the quality of the data received.
Therefore, the majority of visible-light astronomy now rely on terrestrial-based observatories usually situated in secluded areas with a low percentage of daily cloud cover and normally at high altitudes. The second branch is non-optical astronomy. This involves the study of the sky through the use of energies and particles. These include X-rays, gamma rays and infrared and ultraviolet light.
In addition to these two main branches these can be sub-divided into many more fields. Among these are planetary astronomy, which as the name implies is the study of the planets as well as comets and meteors, solar astronomy – the study of the sun, its history and its future – and cosmology, which seeks to identify how the universe looked prior to the Big Bang.
Further subdivisions of astronomy relate to its links with other branches of science. For example, astrogeology is the study of the materials of which the planets consist of and astrophysics is the study of the physical nature of stars and other celestial bodies. Just to further complicate matters, even the practice of astronomy is divided into branches.
Observational astronomy relates to those studies that focus on collecting and analysing data from the universe which is visible. Theoretical astronomy is the use of computer and other analytical models to describe objects and phenomena in space, as well as investigating how these systems may have evolved over time.
These two branches complement each other, as the theoretical takes the findings of observational astronomy and developing them further by exploring their origins and attempting to answer questions that observational astronomy cannot answer by itself.
As well as Galileo and Newton, famous astronomers from the past include Nicolaus Copernicus, Johannes Kepler, Edmond Halley, Carl Sagan and Stephen Hawking.
Among the most notable living astronomers is Neil deGrasse Tyson, Astronomy is one of the few sciences in which amateur astronomers, like Patrick Moore, can make important and lasting contributions, especially in the areas of discovery and the observation of phenomena.
This science has played a crucial role in helping us to understand more about the universe in which we live, where it came from, where it is now and where it may be going in the future. Almost on a daily basis, astronomy furthers our knowledge, establishing new records and redefining what we thought we knew. Although we now know a great deal, there is still so much left to uncover, so many more questions waiting to be answered and it is this which makes astronomy such an endlessly fascinating subject.
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