Earth's Spin & Orbit
Understand that Earth moves in two ways: it rotates (spins) on its axis once every 24 hours causing day and night, and it orbits (travels around) the Sun once every 365 days, which is one year
What a learner can do afterwards
- Demonstrate with a globe or ball that Earth's rotation causes day on the Sun-facing side and night on the opposite side
- State that one full rotation takes about 24 hours (one day)
- State that one full orbit around the Sun takes about 365 days (one year)
1 · Read
Earth is always moving, even though you cannot feel it. It moves in two ways at the same time. It spins around and around like a top, and it also travels in a big circle around the Sun.
When Mia wakes up, her side of Earth is turned toward the Sun, so it is daytime for her. At that same moment, on the other side of the world, it is dark and her cousin is asleep. That is what Earth's spin does: one side faces the Sun while the other side faces away.
Do not mix these up. Spinning gives you day and night. Orbiting all the way around the Sun gives you one year.
Earth spins once every 24 hours to give us day and night, and it circles the Sun once every 365 days to give us one year.
The rewritten readings were written for this dataset.
More to read
Key points: The moon and its motions
Earth spins like a top. One full spin takes 24 hours. That is one day. The side facing the Sun gets daylight. The side facing away gets night. At the same time, Earth travels around the Sun in a big loop called an orbit. One orbit takes 365 days. That is one year. The spin gives us day and night. The orbit gives us the seasons because Earth's axis is tilted. When your hemisphere leans toward the Sun, you get summer. When it leans away, you get winter.
How living things keep time
Many living things keep time with inner clocks close to Earth's 24-hour day. People, other animals, plants and some bacteria have daily patterns of activity and rest. Light is usually their main time signal. As Earth spins, we see the Sun cross the sky. Our bodies use these changing light patterns to time waking and sleep.
The Moon travels around Earth in about 27 days. We see its phases repeat about every 29.5 days. These cycles give life on Earth ways to keep track of time.
Why February gets an extra day
Earth takes about 365.24 days to go around the Sun. Our usual calendar counts 365. The extra time is nearly a quarter-day each year. We add February 29 in years whose numbers divide evenly by four, with no remainder. A year with this extra day is called a leap year. Adding it every four years would be a little too much. Years ending in 00 must also divide evenly by 400. So 2000 got February 29, but 1900 did not. These rules keep the calendar close to Earth's yearly trip.
2 · Watch
En anglaisTake it off screen
Where it sits
Learn first
Optional connections
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.