Physics · Science General

Astronomy and Cosmology

4,498 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 physics in the world of stars evolution and end stages of stars life cycle of stars stars

What is a Star?

  1. A cloud of particles held together loosely by their own collective gravity

  2. A very big collection of matter, mostly gas compressed to incredible pressure and heat by gravity.

  3. A nuclear explosion caused by a growth of hydrogen onto the surface of a white dwarf star

  4. A ball of gas.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A star is a massive, luminous sphere of plasma held together by its own gravity. The intense pressure and heat at the core are necessary to sustain nuclear fusion.

Multiple choice physics in the world of stars evolution and end stages of stars life cycle of stars stars

A star in the main sequence will maintain a constant size

  1. as long as its helium supply holds out.

  2. because its tendency to contract is opposed by the pressure of the hot interior.

  3. until it is devoured by black holes.

  4. provided that gravitational collapse does not overwhelm its photosphere.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

All main sequence stars (including the Sun) are in hydrostatic equilibrium. That is, the inward force of gravity, which tends to compress the star, is balanced by the outward force due to the pressure.

Multiple choice physics in the world of stars evolution and end stages of stars life cycle of stars stars

Stars are believed to originate

  1. in clouds composed largely of hydrogen gas.

  2. when black holes eject excess matter and energy.

  3. when a supernova explode.

  4. when a cloud of helium starts to collapse and breaks into constituent protons (hydrogen atoms).
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Stars form within giant molecular clouds, which are composed primarily of hydrogen gas. Gravity causes these clouds to collapse, eventually leading to the formation of protostars.

Multiple choice physics in the world of stars evolution and end stages of stars life cycle of stars stars

A protostar is a developing star not yet hot enough to engage in the process of:

  1. nuclear fusion

  2. nuclear fission

  3. atomic transmission

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

An object is considered a protostar for as long as material is still falling inward. For our Sun, and stars of the same mass, the protostar phase would have ended after approximately 100,000 years. After this, the protostar stops growing and the disk of material surrounding it is destroyed by radiation.


If the protostar was unsuccessful in acquiring enough mass, a brown dwarf will come into shape. These substellar objects that are unable to sustain hydrogen fusion reactions in their cores, due to their insufficient mass

Multiple choice physics in the world of stars evolution and end stages of stars life cycle of stars stars

The gaseous body that continues to form, now appears as a large red object called a:

  1. protostar

  2. red dwarf

  3. red star port

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

A protostar is an early stage in stellar evolution where a cloud of gas and dust is collapsing under gravity. It is often associated with a glowing, dense, and relatively cool appearance before reaching the main sequence.

Multiple choice physics in the world of stars evolution and end stages of stars life cycle of stars stars

What is the range of star masses for high-mass stars? 

  1. between 500 and about 1,000 solar masses

  2. between 200 and about 500 solar masses

  3. between 8 and about 100 solar masses

  4. between 2 and about 10 solar masses
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Range of star masses for high-mass stars varies from about $8$ to $200$ solar masses.

Answer is $C$.

Multiple choice physics motion and measurement measuring length measurement of small and large distances measurement of distance

Two stars $S _1$ and $S _2$ are located at distances $d _1$ and $d _2$ respectively. Also if $d _1>d _2$ then which of the following statements is true?

  1. The parallax of $S _1$ and $S _2$ are same.
  2. The parallax of $S _1$ is twice as that of $S _2$.
  3. The parallax of $S _1$ is greater than parallax of $S _2$
  4. The parallax of $S _2$ is greater than parallax of $S _1$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$Answer:-$ D

Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines.Due to foreshortning, nearby objects have a larger parallax than more distant objects when observed from different positions, so parallax can be used to determine distances.

Hence parallax of $S _2$ is greater than that of $S _1$

Astronomersuse the principle of parallax to measure distances to the closer stars. Here, the term "parallax" is the semi-angle of inclination between two sight-lines to the star, as observed when the Earth is on opposite sides of the Sun in its orbit.

Multiple choice physics motion and measurement measuring length measurement of small and large distances measurement of distance

A star has a parallax angle p of 0.723 arcseconds. What is the distance of the star?

  1. 1.38 parsecs

  2. 2.38 parsecs

  3. 3.38 parsecs

  4. 4.38 parsecs
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Relationship between a star's distance and its parallax angle:

$d=\dfrac{1}{p}$

The distance $d$ is measured in parsecs and the parallax angle $p$ is measured in arcseconds.

Hence, $d=\dfrac{1}{0.723}=1.38 parsecs$

Multiple choice geography constellations and galaxies constellation different constellations and galaxies milky way
Fill in the blanks:

In Ursa Major, _______ stars form the shape of the handle and ______ stars form the shape of the bowl of the ladle respectively.
  1. $4, 3$
  2. $5, 6$
  3. $3, 4$
  4. $2, 5$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The $7$ prominent stars of Ursa Major for the shape of a big ladle in which $3$ stars form the handle and the other $4$ form the bowl of the ladle.

Multiple choice geography constellations and galaxies constellation different constellations and galaxies milky way
Identify the wrong statement about Ursa major.

  1. It can be used to locate Pole star.

  2. It is seen during winter.

  3. It is also called the Big Dipper.

  4. It has 7 prominent stars.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Ursa Major can be used to locate the Pole star by extending an imaginary straight line towards the north from the last tow stars.

It is also known as the Big dipper and has 7 bright prominent stars which look like a question mark. 
It is seen during summer season and not during winter.