An explosion occurs 340 km away. given that sound travels at 340 m/s, the time the sound takes to reach you is
a. 1 s.
b. 10 s.
c. 100 s.
d. 200 s.
e. more than 200 s.

the working equation for the angular size is the product of the physical size and 360 degrees divided by the product of two pi and distance from earth. the minimum size would be 0.559 degrees while the maximum size would be 0.49 degrees. 

blue light is scattered in different directions by the tiny molecules of air. blue is scattered more than other colours because it has a shorter distance to travel which results in smaller waves. this is why we see a blue sky most of the time.