Galaxies Questions

A galaxy is a system of millions of stars consisting of gas and dust, bound by gravitational force. The sun is one of the stars in the galaxy. Our galaxy is known as the milky way. It appears as a milky band of light in the sky, hence the name. The shapes and sizes of galaxies differ, and the milky way is a large barred spiral galaxy. There are approximately 70,000 million stars in the universe. The Hubble space telescope, launched in 1990, discovered more than 10,000 galaxies by observing a small part of space for 12 days.

The Milky Way’s central black hole, Sagittarius A*, has a mass four million times greater than the Sun. The milky way has a diameter of at least 30,000 parsecs (100,000 ly) and is separated from the Andromeda Galaxy.

Note: IC 1101 is the largest galaxy found in the universe.

Galaxies rotate with respect to their centre. The space between galaxies is known as intergalactic space. Intergalactic space is almost close to an absolute vacuum.

There are four main types of galaxies:

• Elliptical
• Irregular
• Spiral
• Barred spiral

Elliptical galaxy: These galaxies are roughly ellipsoidal with smooth and featureless images. Elliptical galaxies range from tens of millions to over one hundred trillion stars. Some examples of elliptical galaxies are NGC 5 (Andromeda), NGC 67 (Andromeda), NGC 71 (Andromeda), and PGC 1000714.

Irregular galaxy: This galaxy does not have a distinct regular shape and is disordered in appearance, with neither a nuclear bulge nor with traces of spiral arm structure. Some examples of irregular galaxies are The Large and Small Magellanic Clouds.

Spiral galaxy: Spiral galaxies have a bar-like structure known as a barred spiral galaxy. Almost 77% of the galaxies observed are spiral galaxies. The Andromeda galaxy is an example of a spiral galaxy.

Barred spiral galaxies: It is a spiral galaxy made of stars with a central bar-shaped structure. The milky way is a large barred spiral galaxy. Some examples of barred spiral galaxies are M58 (SBc), the Large Magellanic Cloud (LMC, Sm), and M61 (SABbc).

Important Galaxies Questions with Answers

1. Our galaxy is known as the ____

1. Large Magellanic Cloud
2. Andromeda
3. Milky way
4. Small Magellanic Clouds

Answer: c) Milky way.

Explanation: Our galaxy is known as the milky way. The milky way includes our solar system.

2. Do galaxies rotate?

1. Yes
2. No

Answer: a) Yes

Explanation: Galaxies do rotate with respect to their centre.

3. The ____ instrument discovered more than 10,000 galaxies.

Answer: Hubble Space Telescope

Explanation: Hubble Space Telescope is a large and versatile telescope used to observe celestial objects.

4. More than two-thirds of all observed galaxies are _____

1. Barred spiral
2. Irregular
3. Spiral galaxies
4. Elliptical

Answer: c) Spiral galaxies.

Explanation: Almost all galaxies observed are spiral.

5. Write three critical features of the milky way.

Three key features of the milky way are:

• It appears as the milky band of light in the sky.
• The Milky Way galaxy is about 100,000 light-years across.
• It is a Barred spiral galaxy.

6. Match the following

1. Elliptical        1) Milky way
2. Irregular        2) Andromeda
3. Spiral             3) Small Magellanic Clouds
4. Barred spiral  4) NGC 71

Options:

1. a) 1, b) 2, c) 3, d) 4

2. a) 4, b) 3, c) 2, d) 1

3. a) 2, b) 1, c) 4, d) 3

4. a) 4, b) 1, c) 2, d) 3

Answer: 2. a) 4, b) 3, c) 2, d) 1

7. Define galaxy.

A galaxy is a system of millions of stars consisting of gas and dust bound by gravitational force. Examples of galaxies include Andromeda and the Milky Way.

8. M61 (SABbc) is which type of galaxy?

1. Barred spiral
2. Irregular
3. Spiral galaxies
4. Elliptical

Answer: a) Barred spiral.

9. The solar system is present in the milky way.

1. True
2. False

Answer: a) True

Explanation: The milky way is present in the solar system.

10. What is interstellar space?

The space between stars is known as interstellar space.

Practice Questions

1. Choose the Elliptical galaxy.

1. Milky way
2. Small Magellanic Clouds
3. Andromeda
4. NGC 67

2. Define intergalactic space.

3. What are the main types of galaxies?

4. ____ is the largest galaxy found in the universe.

5. State true or false: Galaxies do not rotate.

Watch the video below to know in detail about the star and celestial objects.

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