The reason we have seasons is because, during its journey around the Sun, the Earth is tilted.
How did civilization emerge from small groups of hunter-gatherers? Some archaeologists focus on cooperation as the vital ingredient – and find evidence for it in the form of feast-related artifacts.
The tilt of Earth's axis as it orbits the sun results in the seasonal changes.
A solar day is a measure of how long it takes the Earth to rotate from one noon to the next, and today's summer solstice also happens to be the longest solar day of the year.