Physics · Science General

Astronomy and Cosmology

4,450 Questions

This topic provides questions on astronomy, cosmology, and the physical universe. It covers subjects like the Hubble sequence, constellations, dark matter, and stellar evolution. These questions help build a strong foundation for general science exam sections.

Galaxies and clustersConstellations and starsStellar evolutionSpace observatories

Astronomy and Cosmology Questions

Multiple choice

What is the biggest type of star?

  1. White dwarf

  2. Red giant

  3. Supergiant

  4. Blue giant
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Supergiants are the largest stars in the universe in terms of physical volume. They are significantly larger than red giants, white dwarfs, or blue giants.

Multiple choice

How many stars are there in the Milky Way?

  1. 200 billion

  2. 5

  3. 6 million

  4. 700
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Scientific estimates for the number of stars in the Milky Way galaxy typically range between 100 billion and 400 billion. 200 billion is the most widely accepted average estimate.

Multiple choice

What are stars mainly made of?

  1. Rock

  2. Hot liquid

  3. Hot gas

  4. Dust particles
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Stars are primarily composed of hot gas, specifically hydrogen and helium, held together by gravity. The extreme pressure and heat cause nuclear fusion in their cores.

Multiple choice

Which is the closest star to the Sun?

  1. Sirius

  2. Alpha Centauri

  3. Mercury

  4. Proxima Centauri
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Proxima Centauri is the closest star to our solar system, located about 4.24 light-years away. It is part of the Alpha Centauri star system.

Multiple choice

What is our home galaxy called?

  1. The Rosy Road

  2. The Big Bang

  3. The Milky Way

  4. The solar system
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Our solar system is located within the Milky Way galaxy. It is a barred spiral galaxy.

Multiple choice

Which sort of star is the sun?

  1. Supergiant

  2. Red giant

  3. Main sequence

  4. White dwarf
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The Sun is classified as a G-type main-sequence star. It is currently in the stable phase of its life cycle, where it fuses hydrogen into helium.

Multiple choice stefan's law black body radiation heat transfer thermal properties physics

In the Orion stellar system the shining of a star is $17\space \times 10^3$ times that of the sun. If the temperature of the surface of the sun $6 \times 10^3 K$ then the temperature of this star will be

  1. 273 K

  2. 652 K

  3. 6520 K

  4. 68520 K
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The power radiated is directly proportional to the fourth power of the absolute temperature.
$P \propto T^{4}$
$P = kT^{4}$ 

Let P = Power radiated by the sun
Power radiated by star $ = 17 \times  10^{3}P $
$\dfrac{T _{star}^{4}}{T _{sun}^{4}} = 17 \times  10^{3}$

$\dfrac{T _{star}}{T _{sun}} = 11.418$

$T _{star} = 6000 \times  11.418 = 68,511K$

Hence, the answer is option D.

Multiple choice physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

What name is given to the type of astronomy having the following characteristics.
I. It is carried out in the waveband $300$nm to $10$nm.
II. The atmosphere is opaque to the incoming radiation from space
III. Observations are to be carried out from above the earth's atmosphere.

  1. X-ray astronomy

  2. Ultra-violet astronomy

  3. Infra-red astronomy

  4. Gamma ray astronomy
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Ultra-violet astronomy is carried out in waveband of $10nm-300nm$ in which is above earth's atmosphere.
Multiple choice

Which of the following is not a characteristic used to classify stars?

  1. Mass

  2. Temperature

  3. Luminosity

  4. Color
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Color is not a fundamental property used to classify stars. Instead, stars are classified based on their mass, temperature, and luminosity.

Multiple choice

What is the main source of energy in stars?

  1. Nuclear Fusion

  2. Gravitational Contraction

  3. Chemical Reactions

  4. Radioactive Decay
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Stars generate energy through nuclear fusion reactions, where lighter elements are combined to form heavier elements, releasing vast amounts of energy.

Multiple choice

Which type of star is the most common in the universe?

  1. Red Dwarfs

  2. White Dwarfs

  3. Neutron Stars

  4. Black Holes
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Red dwarfs are the most common type of star, making up about 85% of all stars in the Milky Way galaxy.

Multiple choice

What is the final stage in the evolution of a massive star?

  1. Supernova

  2. Neutron Star

  3. Black Hole

  4. White Dwarf
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Massive stars end their lives in a supernova explosion, which can be so powerful that it can outshine an entire galaxy.

Multiple choice

What is the remnant left behind after a supernova explosion?

  1. Neutron Star

  2. Black Hole

  3. White Dwarf

  4. Red Giant
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

If the core of a massive star is sufficiently massive, it collapses into a neutron star after a supernova explosion.

Multiple choice

What is the fate of a low-mass star like our Sun?

  1. Supernova

  2. Neutron Star

  3. Black Hole

  4. White Dwarf
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Low-mass stars like our Sun end their lives as white dwarfs, which are dense remnants that have exhausted their nuclear fuel.