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 physics constellations and galaxies light year evolution and end stages of stars in the world of stars

The distance of a galaxy from the earth is of the order of $10^{25}$ m. The time taken by light to reach the earth from the galaxy is

  1. $3 \times 10^{14}$ s
  2. $3 \times 10^{16}$ s
  3. $3 \times 10^{18}$ s
  4. $3\times10^{20}$ s
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Speed of light, c = 3 x 10$^8$ m s$^{-1}$
Time taken by light to reach the earth from the galaxy is
$\displaystyle t = \frac {10^{25}m}{3\times 10^8m\,s^{-1}}\,=\,3\times 10^{16}s$

Multiple choice physics constellations and galaxies light year evolution and end stages of stars in the world of stars

The method of measuring distance to stars beyond 100 light-years is

  1. Capheid variable stars

  2. Heid variable stars

  3. Lowheid variable stars

  4. None
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The brightness of the stars changes over time. The difference in the brightness over time allows calculating the distance to the star. This is the cepheid variable stars method that is used to measure the distance to stars beyond 100 light years.

The method of measuring the distance to stars beyond 100 light-years is  Cepheid variable stars

Multiple choice physics constellations and galaxies light year evolution and end stages of stars in the world of stars

Which is the another unit used by astronomers for measuring distance to other parts of Milky Way Galaxy?

  1. Km

  2. Light year

  3. Parsec

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

Units used in astronomy by astronomers are an astronomical unit, light year and parsec.

another unit used by astronomers for measuring the distance to other parts of Milky Way Galaxy is Parsec

Multiple choice physics constellations and galaxies light year evolution and end stages of stars in the world of stars

How can Cepheid variable stars helpful to figure out true brightness?

  1. These stars change their brightness over time

  2. These stars lower their brightness over time

  3. These stars raise their brightness over time

  4. None
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The brightness of the stars changes over time. The difference in the brightness over time allows calculating the distance to the star. This is the cepheid variable stars method that is used to measure the distance to stars beyond 100 light years.

These stars change their brightness over time

Multiple choice physics constellations and galaxies light year evolution and end stages of stars in the world of stars

The nearest star to the Earth (apart from the Sun) is 'alpha centauri' which is about .......... away form the Earth

  1. 4.3 light years

  2. 3.26 light years
  3. $4.3 \times 10^{12}$ km
  4. $3.26 \times 10^{15}$ km
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Alpha century is a star system closest to earth other than sun. Its distance from the earth is about $4.367$ light years.

Multiple choice physics constellations and galaxies light year evolution and end stages of stars in the world of stars

How does astronomer calculate distance of star?

  1. Comparing apparent brightness of star to true brightness

  2. Comparing true brightness of star to apparent brightness

  3. Comparing true brightness of star to true brightness

  4. None
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The brightness of the stars changes over time. The difference in the brightness (difference in the apparent brightness to the true brightness) over the time allows calculating the distance to the star. This is the cepheid variable stars method that is used to measure the distance to stars beyond 100 light years.

Comparing the apparent brightness of the star to true brightness