# Astronomy- The Science of Space

When you look at the night sky, you admire the fascinating beauty of millions of stars and galaxies of the universe. Humans have looked in awe and wondered what those twinkling dots of light are, since ancient times. Due to their inborn curiosity, humans have found answers to their questions and ventured deeper into the unknown.

Today, many spacecrafts have been sent beyond our little world -earth -and humans have even walked on the moon! All this has been possible only because of our thirst to know more. So, space has its own separate branch of science- Astronomy.

What is astronomy?

Astronomy is the branch of science dealing with the study of the universe. There are two major types of astronomy- observational and theoretical. In observational astronomy, many different types of electromagnetic waves like X-rays , gamma rays, microwaves, UV rays, infrared and visible light. Theoretical astronomy mainly deals with simulations and creating theoretical models to predict the observations.

Distance in astronomy

We know that the universe is a very very large place. So, to measure distance in the cosmos we need bigger units of length than kilometers:

Astronomical unit(AU): It is used to define the distance between Earth and the Sun. 1AU is equivalent to 149 million kilometers (93 million miles).

Light year(ly): It is defined as the distance travelled by light in one year. The speed of light is 300,000 kilometers per second. So 1ly is equal to 9.5 trillion kilometers(a lot right!).

Parsec: It is  defined as the distance at which the mean radius of the earth’s orbit subtends an angle of one second of arc. 1 parsec is equal to 3.26light years.

Some fun facts:

• The limit of the visible universe is about 46.5billion light years(radius) which equals to 4.4* 10^26metres (humongous!).
• The universe is about 13.8billion light years old.
• The universe formed as a result of the Big Bang-literally a single point expanded to form the universe!
• The universe is expanding at the rate of 72 kilometers per second.
• There are more than one hundred thousand million stars in our galaxy (the milky way). Imagine if there are trillions of galaxies like our own, how many stars would that be!
• The death of the universe is not completely predicted yet. Some say that it will become a dark and cold place when all the stars die. Others say that the universe will end with “the Big Crunch”.
• When you look at the sun, you look about 8 minutes into the past, since light has taken 8 minutes to reach us.
• The milky way has a supermassive black hole at its center- Sagittarius A*

Are we alone?

We haven’t found any other life in the universe but the search is on. Since there are billions of stars, the chances of them having earth like planets are high. So, there probably are “aliens” out there, we just haven’t found them yet or they haven’t found us yet. Sadly, the chances of having contact with a developed alien life like us are very low. However, that won’t stop us from looking. Hopefully, we will find them soon (and let them be friendly!).

Astronomy is a diversified branch with biology, geology, chemistry, mathematics and physics, all different types of fields coming together. There is a lot of scope for a great career in this discipline. Besides, who wouldn’t want to find out the secrets of the universe.

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