★Galaxy
The galaxies are made up of millions of stars held together by the force of gravity and these stars account for most of the masses of the galaxy. Andromeda is our nearest galaxy.
Galaxy are giant assemblies of stars, planets, gases and dust. These stars occur in huge bunches or clusters. They are so big that they have sometimes been called Islands Universe. Milky way and Andromeda are two examples.
Our own galaxy is called the milky way (or the Akash Ganga) and it contains about 300 billion stars and one of these is our Sun. Planets and other objects go round the Sun and make up the solar system with the Sun at the centre.
In 1924, Edwin Hubble first demonstrated existence of galaxies beyond milky way.
Structurally, the galaxies are found in three forms which are as follow
i. Spiral have a central nucleus with great spiral arms. Milky way and Andromeda are the examples.
ii. Elliptical without spiral arms.
iii. Irregular with no shape.
10 mcqs about galaxy:
1. What is a galaxy primarily made of?
A) Stars, gas, dust, and gravitational forces
B) Planets and moons
C) Only stars
D) Asteroids and comets
Answer: A) Stars, gas, dust, and gravitational forces
2. Which type of galaxy is our Milky Way?
A) Elliptical
B) Irregular
C) Spiral
D) Dwarf
Answer: C) Spiral
3. What holds the components of a galaxy together?
A) Magnetic forces
B) Gravitational forces
C) Electromagnetic forces
D) Nuclear forces
Answer: B) Gravitational forces
4. Which of the following is NOT a type of galaxy?
A) Spiral
B) Elliptical
C) Circular
D) Irregular
Answer: C) Circular
5. Approximately how many stars are present in the Milky Way galaxy?
A) 100 million to 400 million
B) 100 billion to 400 billion
C) 1 billion to 10 billion
D) 50 million to 100 million
Answer: B) 100 billion to 400 billion
6. Which type of galaxy contains mostly older stars?
A) Spiral
B) Elliptical
C) Irregular
D) None of the above
Answer: B) Elliptical
7. What type of galaxy has no defined shape?
A) Spiral
B) Elliptical
C) Irregular
D) Dwarf
Answer: C) Irregular
8. Where is our solar system located?
A) In an elliptical galaxy
B) In the Milky Way galaxy
C) In an irregular galaxy
D) In a circular galaxy
Answer: B) In the Milky Way galaxy
9. What is the central bulge in a spiral galaxy composed of?
A) New stars
B) Old stars
C) Planets
D) Asteroids
Answer: B) Old stars
10. What is the significance of galaxies in the universe?
A) They are mostly empty space
B) They contain solar systems, stars, and planets
C) They only contain stars
D) They are made of dark matter alone
Answer: B) They contain solar systems, stars, and planets
