1. Day & Night: Earth's Two Motions

Earth is always doing two things at once, and mixing them up causes a lot of confusion. It spins like a top, and it travels around the Sun.

• Rotation is Earth spinning on its axis, an imaginary line through the North and South Poles. One full spin takes about 24 hours — that's what gives us day and night. The side facing the Sun has day; the side facing away has night.
• Revolution is Earth orbiting the Sun. One full trip takes about 365 days — that's one year.

Earth's axis is tilted (about 23.5°), and it stays pointed in the same direction as Earth orbits. That steady tilt is the secret behind the seasons (Lesson 5).

⚠️ Common misconception: day and night are not caused by Earth moving closer to or farther from the Sun, and the Sun does not actually 'rise' and travel across the sky. It is Earth's rotation that carries us into and out of sunlight.

💡 Tip: Rotation = spin = 1 day; Revolution = orbit = 1 year. Don't confuse the two.