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Da VIP Academy / GED / Science / Earth & Space Science

Space Science

Explain day/night, seasons, moon phases, and the structure of the solar system.

Practice this skillAll Science skills

How it works

Rotation vs revolution

Earth rotates once a day (day and night) and revolves around the Sun once a year. Seasons come from Earth's 23.5° tilt, not from distance to the Sun.

Moon phases

The Moon does not change shape — we see different amounts of its lit half as it orbits Earth over about 29.5 days.

Worked examples

  1. Why is it summer in the northern hemisphere in July?

    1. Earth's axis is tilted.
    2. In July the north tilts toward the Sun.
    3. Sunlight strikes more directly and days are longer.

Words to know

Revolution
One full orbit around another body.

Test-day tips

  • • Seasons = tilt. Distance is a common wrong answer.
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