Rotation: Day and Night: Concept Map

24 min
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Concept Map

Organise the vocabulary, quantities and relationships into a connected model.

This extension applies that lens specifically to Rotation: Day and Night.

The Earth spins on its axis — an imaginary line running through the North and South Poles — once every 24 hours. This spinning is called rotation.

The Sun can only light half of a ball at a time. So at every moment, half of the Earth faces the Sun and has day, while the other half faces away and has night. As the Earth turns, your town is carried into the lit half (sunrise), across it, and out of it again (sunset).

The Earth rotates from west to east. That is why the Sun appears to rise in the east, cross the sky, and set in the west. The Sun is not travelling across the sky at all — you are being turned past it.

Worked example — degrees per hour. A full turn is 360360^\circ and it takes 24 hours, so the Earth turns

360÷24=15 every hour360 \div 24 = 15^\circ \text{ every hour}

That single number explains time zones: places 1515^\circ apart in longitude see the Sun at its highest one hour apart. When it is midday in Johannesburg, the Sun has not yet reached its highest point over Rio de Janeiro.

The common mix-up. Rotation and orbit are two different motions with two different periods:

MotionWhat it isHow long
rotationthe Earth spinning on its axisabout 24 hours → day and night
orbit (revolution)the Earth travelling around the Sunabout 365¼ days → one year

Natural Sciences — Grade 7 — Concept Map: What causes day and night on Earth?

Natural Sciences — Grade 7 — Concept Map: What is the name of the imaginary line through the North and South Poles that the Earth spins around?

Natural Sciences — Grade 7 — Concept Map: The Earth turns through a full circle of 360° in about 24 hours. Through how many degrees does it turn in one hour?

Name the original topic being extended by this concept map lesson.

Which statement is the best evidence-led starting point for Rotation: Day and Night: Concept Map?