Due to

Sir,

1.Due to the rotation of the earth day and night are formed.

What is "due to" fuctioning here. I somewhere read that "due to" is an adjective ,If so, then actually what it modifies.

Please expalin the usage of "due to".

2.Due to the rotation of the earth days and nights are formed.

Here, I have changed the "day" into "days" and "night" into "nights".

IS the sentence still correct?

Thanks.