What is Galaxy?
Answers
Answer:
A galaxy is a gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter. The word galaxy is derived from the Greek galaxias (γαλαξίας), literally "milky", a reference to the Milky Way
What is Galaxy?
A galaxy is a sprawling space system which is composed of stars, dust, interstellar gas, stellar remnants, and dark matter and all held together by gravity.
The word ‘Galaxy’ is termed from the Greek word ‘galaxies‘. It is tough to tell how big the universe is! The universe has many galaxies, and each carries millions of stars which are bounded by a unique force known as gravitational force. There are approximately 70,000 million stars in the universe. The solar system where our earth exists is in the Milky Way Galaxy.
Types of Galaxy:-
Elliptical Galaxies
These type of galaxies are like flattened balls of old stars and contain very little gas. It also includes the most massive galaxies containing a trillion stars.
Spiral Galaxies
Spiral galaxies have a flattened the shape. They have a bulge in the centre composed of old stars surrounded by a disk of young stars and are arranged in spiral arms.
Irregular Galaxies
As its name suggests, Irregular Galaxies have no particular shape. There are billions of galaxies in the universe, the centre of the galaxy releases a huge amount of heat, radiation, radio waves and x-rays.
1.What Galaxy is Earth in?
Ans-The Milky Way: It is the home galaxy of our planet. The spiral arm of the Milky Way is made up of giant clouds of gas and dust with star clusters. Some parts of the galaxy are also made of dark matter. Our galaxy consists of four spiral arms which emerge from the central bar.
2.What Type of Galaxy is the Milky Way?
Ans-Bared spiral galaxy- The shape of the Milky Way galaxy is of barred spiral type. The stars that we see at night are part of it. The galaxy appears as a milky band of light in the sky, that's why it is called the Milky Way Galaxy.
3.What is the Milky Way Made of?
Ans-The Milky Way galaxy is made up of approximately 90% dark matter and about 10% “luminous matter.” This large amount of dark matter initiates an invisible halo which causes the Milky Way to spin.
4.What is in Between Galaxies?
Ans- The space between galaxies is known as intergalactic space, similarly the space between stars is called interstellar space. Intergalactic space is almost close to an absolute vacuum.
Very little quantity of dust and debris are found in interstellar space. Based on the calculations, scientists estimate that one hydrogen atom is present per cubic meter of interstellar space.
5.What are Galaxies Made of?
Ans-The Formation of galaxies is still uncertain. The entire cosmic space was entirely made up of hydrogen and helium after Big Bang. Some astronomers believe that the dust and gas were pulled together by gravitational force, which later formed the stars.
The stars formed drew closer to each other, and along gas and dust formed the galaxies. The heavier elements of the galaxies were formed consequently by the strong gravitational force bringing hydrogen and helium.
6.Do Galaxies Move?
Ans-Yes, galaxies move and rotate through space. Galaxies rotate with respect to their center. The portion of the galaxy located near its center rotates slowly, and the portion of the galaxy located near the edge of the galaxy rotates very fast.
Galaxies also move away from each other, which occur due to the expansion of the universe, after the Big Bang. A cluster (a group of galaxies) also rotates with respect to its center of mass.
4.How Many Galaxies are in the Universe?
Ans- It is believed that there are around 100 billion galaxies. This estimate is found out by counting the number of galaxies in a small area of the sky.
