Question

Why astronauts see dark sky in space unlike blue sky on earth:
(A) There is no day in space
(B) Light is not scattered in space since there are no particles present
(C) Light is reflected back from the body of the astronaut
(D) Light is absorbed by the space

Answer 1

Hint: The blue color of the sky is because of the scattering of the sunlight due to particles in the atmosphere. In space there aren’t many tiny particles or there isn’t much dust which can scatter the sunlight. Hence, we don’t see any color. And this absence of light, is seen as darkness.

Complete step by step answer:
Sunlight reaches the earth’s atmosphere and is scattered in all directions by particles present in air. Blue has maximum frequency and lowest wavelength. Lower wavelengths are much more effectively scattered by the particles of that particular size.
There is no atmosphere in space. Sun’s radiations will not penetrate into space. There is no difference between days and nights. Days and nights are dark.
Absence of atmosphere in space will result in no light there. Reflection, absorption and scattering will not take place.

All the above criteria will satisfy option B i.e., light is not scattered in space since there are no particles present.

Note:
We can use the method of elimination here.
Option A talks about “day” in space. Day and Night are due to the rotation of the planet. And we might know that the skies of different planets can be of different colors. Hence this is incorrect
Option C: An astronaut’s suit is white so it scatters/reflects all the colors equally, hence there should not be blackness in the pictures. Instead, everything should be bright.
Option D: Absorption happens due to particles. When we say “space”, we are referring to vacuum. And vacuum cannot absorb light. Hence the statement itself is wrong.
Hence, we see that these options don’t make sense in the scenario. So, we can eliminate them and consider option B as the correct one.