Silly old Earth, is so tired it leans to the side. But it is the leaning that makes the seasons, and the fact that the length of the day and night vary according to the season.
I asked myself a question in entry below ...Called Drat... if days and nights are all the same length at the equator. So I printed a picture of the globe and the sun and reasoned it out.
You have noticed that world maps on globes are always mounted so that the Globe tilts to one side. The globe tilts because the Earth tilts, 23 degrees in fact, from the plane of its orbit. So, as the Earth orbits around the Sun, the north pole is pointed away from the sun and then toward the sun, once each year. When the north pole is pointed toward the sun, it is summer (in the Northern half of the world) and when the north pole is pointed away from the sun it is winter in the north.
"Ah, hah," I hear the brighter children ask, "But what about the Southern half of the world." They don't know the word hemisphere.
"Just the opposite," I tell them. "When it is winter in the northern half of the world, it is summer in the southern half."
"But when is Christmas," they cry. First things first for kids.
"Chrismas comes right in the middle of summer." The children fall back in their chairs aghast. Santa in a fur trimmed red suit being pulled in a sleigh thrugh the summer heat is more than they can deal with.
But what has this to do with the length of the day? Well, Big Children, when the northern hemisphere is pointed at the sun, any location gets more sun, and the day is longer. When it is pointed away from the sun, the opposite is true. There are longer nights.
The farther north you go, the longer each summer day is. How long can it get? Well, at the north pole, a day can be 24 hours long. Huh?
That's right. At the north pole, the sun comes up on March 21st and stays up, until September 21st. How's that for daylight savings time?
Of couse, when it sets, it is gone for six months. Alas.
But my original question was, Are the days and nights always the same length at the equator? Looking at the globe and the sun, I would say "yes. Days and nights at the equator are always the same: twelve hours each."