A childhood belief about general

When I was young, I used to wonder
how different things got their
names. When I was about eight years
old, I remember walking to, and from,
church, every Sunday morning, with my
dad. I thought Sunday must have been
called that, because it was sunny.
The only problem was, it always seemed
that my dad and I would get caught in
rain showers, on our walks, every Sunday.
I couldn`t understand this, and I
remember, on countless occasions, asking
my dad why they called it Sunday. I
told him I thought they should have
called it RAINDAY!