Tag: constellations and galaxies

Quizzes (4) Questions (52)

Questions Related to constellations and galaxies

Multiple choice geography constellations and galaxies constellation different constellations and galaxies milky way

Fill in the blank:

The 3 middle stars in Orion represent the ________.

  1. belt of the bear

  2. belt of the hunter

  3. tail of the bear

  4. stick of the hunter
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Constellations were phrased by ancient people to enable easy recognition of stars. Constellations resemble objects that were familiar to those people. Orion resembles the hunter, and the 3 middle stars of the constellation represent the belt of the hunter.

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 $6563 A^0 H _\alpha$ line emitted by hydrogen in a star is found to be red-shifted by $15 A^0$. The speed with which the star is receding from the earth is

  1. $3.2 \times 10^5m s^{-1}$
  2. $6.87 \times 10^5m s^{-1}$
  3. $2 \times 10^5m s^{-1}$
  4. $12.74 \times 10^5m s^{-1}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Wavelength of $H _\alpha$ line, 
$\lambda=6563A^o$
$=6563\times10^{-10}$


Redshift observed in star $(\acute{\lambda-\lambda})=15A^o=15\times 10^{-10}$

Let the velocity of the star with which it is receding away from the earth be v.
Red shift relation, $\acute{\lambda}-\lambda$=$\dfrac{v}{c}\lambda$

$=\dfrac{c}{\lambda}\times (\acute{\lambda}-\lambda)$

$=\dfrac{3\times 10^8\times 15\times 10^{-10}}{6563\times 10^{-10}}$
$=6.87 \times 10^5m s^{-1}$

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

What is known as Astronomical Unit (AU)?

  1. Average distance between Earth and Sun

  2. Average distance between Sun and Moon

  3. Average distance between Moon and Earth

  4. Average distance between Earth and Star
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Average distance from the centre of the Earth to the centre of the Sun forms the astronomical unit (AU). It equals to around 149.6 million kilometres.