Tag: constellations and galaxies

Quizzes (4) Questions (52)

Questions Related to constellations and galaxies

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

If the light from star $A$ takes $15$ min to reach star $B$ and the speed of light is $3\times {10}^{8}m/s$, then what is the distance between the stars?

  1. $2.7\times {10}^{8}km$

  2. $2,9\times {10}^{11}km$

  3. $2.7\times {10}^{8}m$

  4. $36\times {10}^{9}km$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Given $t=15$min
Speed of light $=3\times {10}^{8}m/s$
$\therefore$ $t=15min=15\times 60=900 sec$
By using the formula
$Speed=\cfrac{Distance}{Time}$
$Distance=Speed \times time$ $=3\times {10}^{8}m/s\times 900 sec$ $=2700\times {10}^{8}m$ $=2.7\times {10}^{8}km$

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