Question

The rainbow is an example of the dispersion of sunlight by the water drops in the atmosphere. This is a phenomenon due to combined effect of dispersion refraction and reflection of sunlight by spherical water droplets of rain. The conditions for observing a rainbow are that the sun should be shining in one part of the sky (say near western horizon) while it is raining in the opposite part of the sky (say eastern horizon). An observer can, therefore, see a rainbow only when his back is towards the sun.

The colour of clear sky from the earth appears blue but from the space it appears black. Why ?

Which of the following statement is not correct

Assertion: Planets twinkle but stars do not. Reason: Twinkling of stars is due to atmospheric refraction