Astronomy

Astronomy vs Cosmology

What are stars made of? Which is the galaxy nearest to us? What are black holes? How was the universe formed? Will our sun die?

One of the most intriguing and fascinating fields of study in science is the field of Astronomy. It is the study of our universe – tracking the motions of stars, planets, comets, and all other heavenly bodies, determining how they are formed, and their composition. There is a specialized branch of astronomy, named Cosmology, which deals with understanding things on an even larger scale – how, and how long ago, did the universe form, how did it appear in its early state, what is its current state, and whether and how it will eventually end.

Astronomy attempts to find answers to many such questions that puzzle scientists and all of us humans.

Studying the Universe

From the earliest days, humans have looked up at the open sky to observe what’s happening in the universe. At first, it was only with the naked eye. Then the telescope was invented. The telescope enabled astronomers to get a magnified view of the moon, the planets, and the stars. The humble telescope, invented in the days of Galileo and Newton, has become very sophisticated over the years and is today installed in space observatories, satellites, and spacecraft sent on space missions.

The most famous of these space probes is the Hubble Space Telescope which has been hurtled into distant space with powerful telescopes to study distant bodies even more closely.

The Hubble Space Telescope

How was our Sun formed?

Our sun was formed about 4.5 billion years ago, together with all the planets including the earth. Our sun is a star. All-stars have a lifecycle – they are formed, they burn brightly, and then they eventually die. How are they formed and how do they die?

1. Stars are created from giant, swirling clouds of gas and dust which are pulled together by gravity to form a dense ball.
2. As the ball gets squeezed it becomes very hot and starts to expand, glowing brightly as it lets the heat out.
3. A chemical reaction that converts hydrogen into helium is occurring at its core. This reaction is called Nuclear Fusion.
4. It stays in such a stable condition for millions or even billions of years.
5. Eventually, it runs out of hydrogen and stops generating heat. The core begins to contract while the outer shell expands rapidly. The star becomes a Red Giant.
6. Eventually, it explodes, spewing gas and dust all around. This is known as a Supernova Explosion.
7. In some cases, the core becomes super-dense matter and creates a Black Hole, which attracts and swallows all nearby matter and energy, including light.

Our sun too will die one day, but that day is estimated to be at least 7 or 8 billion years away!

Check Point

1. ________ is a specialized branch of astronomy.
2. The origin of the universe began with an explosion called the _________.
3. The big bang occurred at a ________ which had infinite density and gravity.
4. The chemical reaction occurring at the core of a star is called _______.
5. A star which stops generating heat and begins to contract is called a________.
6. When a star eventually explodes, it is known as a _______.

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