Question

occurence of day and night

Answer 1

'''Day and night:'''
The Earth rotates on an axis. When it rotates, half of the Earth is exposed to the sun and half is not. When a part of the earth is exposed to the sun it is ''day'' and when it is not exposed to the sun it is ''night.'' Pretty simple. 


'''The seasons:'''
axis------> / 
Earth--> (/)-------O<--Sun 
axis----> / 

Earth's axis is tilted so in summer (for the Southern Hemisphere) the Southern Hemisphere is in the sun longer than the Northern Hemisphere. 

Answer 2

the days and nights occur due to rotation.