Astronomy for beginners - 1

Out of all branches of science which we currently know about, many find astrophysics to be the most interesting subject to learn. This is because of the mysterious sci-fi stories which we constantly encounter while watching movies, or reading related novels. Beginners, who will not be knowing anything about astrophysics concepts cannot enjoy sci-fi stories to its fullest, and they will not have a sound knowledge of the path which they have to follow to learn the subject effectively.

So, in the next few series of posts, I will write about astronomy, and in particular, astrophysics, so that many people, who are in a confusion of how to start will be benefitted.
 --> So, what is astronomy? 
Astronomy is a branch of physics (which is inturn a branch of science) which deals with the science involving celestial bodies. It includes various other branches of science like chemistry, geology, and most importantly, mathmatics. It includes motion, and other astronomical phenomena of objects outside Earth's atmosphere.
    It is considered to be one of the oldest natural sciences, practised by many astronomers for thousands of years. But the only branch of astronomy active during a very long time was "Observational Astronomy". People used to observe the motion of stars and planets in the night sky, visible to the naked eyes, and predicted many astronomical activities. (Remember, math was not developed much, and the predictions lacked mathematical proofs).

Nicolaus Copernicus' "Heliocentric" model of the universe. 

But later, in the 16th century, there was a scientific revolution, upon Nicolaus Copernicus' prediction of the "Heliocentric model" of the universe, which was later developed by Galileo Galilei and Johannes Kepler, who, then formulated a very accurate model to describe the motion of celestial bodies around the sun (Kepler's laws of planetary motion). Then in 17th century, Newton proposed his law of universal gravitational, which brought another scientific revolution in the field of astronomy. It's predictions, limitations, and the theory proposed to overcome those limitations (u might have already guessed it!!) will be explained in detail in my future posts.

    Coming back, astronomy could be broadly classified into 
1. Astrophysics - It deals with extragalactic astronomy, stellar astronomy, solar physics, compact objects, and many more;
2. Astrobiology - It deals with the evolution of biological systems in the Universe, and many more;
3. Astrochemistry - It deals with the chemical compositions of many celestial objects, their atmospheric composition, and many more;
4. Planetary science - It includes atmospheric science, exoplanetology, planetary formation, and many more;
     Astronomy could also be classified on the basis of the techniques used for research in the subject as,
1. Observational astronomy
2. Theoretical astronomy. 
Observational astronomy deals with the observations of celestial objects throughout the EM spectrum, and measure it's motion around any other massive celestial body, it's position in this vast cosmos, it's surface and atmospheric composition by measuring the spectra of the light emitted, or reflected or passed through them. Many of these observed phenomena require a mathematical model for its precise explaination, hence, we need theoretical astronomy. It takes in the data acquired upon observation, and theoretical astronomers develop a mathematical explaination. If the observation turns out to be strange, then a new "Hypothesis" is proposed to support the observation. One of the most important property of this hypothesis is, it must "predict" certain events. If those events are observable, and if they are proven to be correct, then that hypothesis is considered to be a "theory".
     Observational astronomy could be further classified as :-
1. Radio astronomy 
2. Submillimetre astronomy 
3. Infrared astronomy 
4. Optical astronomy 
5. Ultraviolet astronomy 
6. X-ray astronomy 
7. Gamma-ray astronomy 
8. Neutrino astronomy 
9. Cosmic ray astronomy
10. Gravitational wave astronomy 
     Theoretical astronomy includes topics like,
1. Theoretical astrophysics, 
2. Theoretical chemistry
3. Theoretical chemical and 
4. Theoretical physical astronomy, and many more.
      I have purposefully not explained any of them above, as it consumes more space and time (but not space-time!!).

P.S - In my upcoming posts, I'm gonna explain all of the above mentioned topics in detail.

Thank you .

By, 
H. B Chaitanya Bharadwaj 

You can write me at 
chaitanyabharadwaj2000@gmail.com