Planet Earth & Beyond
The solar system, seasons, fossils
The Solar System
Our solar system has eight planets orbiting the Sun. In order: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. Earth is the third planet and the only one known to support life. The Moon orbits Earth approximately every 27 days.
Why We Have Seasons
Earth is tilted on its axis at 23.5°. As Earth orbits the Sun, different parts receive more or less direct sunlight. In South Africa (Southern Hemisphere), summer is from December to February and winter from June to August — the opposite of the Northern Hemisphere.
Example
Fossils Tell a Story
Fossils are preserved remains or traces of organisms from millions of years ago. South Africa is rich in fossils:
• The Cradle of Humankind (Gauteng) — early human fossils
• The Karoo — ancient reptile and plant fossils
Fossils help scientists understand how life on Earth has changed over time.
Note
Remember
A day is one rotation of Earth on its axis (24 hours). A year is one orbit of Earth around the Sun (365¼ days). The extra quarter-day gives us a leap year every 4 years.
Key Vocabulary
Solar systemThe Sun and all the planets and objects orbiting it
OrbitThe curved path an object takes around another in space
AxisAn imaginary line through Earth from pole to pole
FossilThe preserved remains or traces of ancient organisms
RotationSpinning on an axis (Earth rotates once in 24 hours)
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Solar system
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