What are the reasons for seasonal changes on Earth?

[Seasons]

Some mail I received said I had to introduce myself. (and get an avatar - that sounds like a headache!)

I don't really know much about the topics in this board, so I'm probably just going to examine the one topic I posted on. I've been very appreciative of the responses.

 

[rootone]

I'm sure there is no requirement to formally introduce yourself or make an avatar so you can post in this forum.
Anyway though, Hi there. Welcome to PF.