SC.4.E.5.3 The Earth’s Day and Year

 SC.4.E.5.3: Recognize that Earth revolves around the Sun in a year and rotates on its axis in a 24-hour day.

What Makes a Day and a Year?

The teacher’s chair in your classroom is made so that it can spin around in a circle. The teacher sitting in the chair can face the computer, then spin around to face the class. If the teacher spins all the way around in the chair, the teacher has spun around in a 360-degree circle.

In science, the spinning of an object in a 360-circle is called rotation. Then imaginary line through the center of the object is called an axis. The Earth rotates on its axis once in a 24-hour day. The rotation of the Earth in a 24-hour day is what causes the cycles of day and night.

The teacher’s chair in your classroom also has wheels. The chair can be moved around the room. Imagine if there were no other chairs or tables in your classroom. You might be able to put a kickball in the center of the room. Then you might be able to wheel the chair in a complete circle around the center of the room.

The movement of one object around another object in space in a complete circle is called a revolution. The Earth moves through space in a path around the Sun. That path is called an orbit. It takes the Earth one year, 365 days, to complete one revolution around the Sun.

The rotation of the Earth around its axis in a 24-hour causes the cycles of day and night. The revolution of the Earth in its orbit around the Sun causes the 365-day cycle of one year.