Netherlands VWO 6 (eindexamenjaar) General Natural Science

1. Solar system and universe

Structure of the solar system and universe · Space in daily life · Knowledge about the universe

• The Solar System – The Solar System is the Sun and everything its gravity holds: 8 planets, their moons, dwarf planets, asteroids, comets and dust. The inner four planets (Mercury, Venus, Earth, Mars) are small and rocky. After the asteroid belt come the giants: gas giants Jupiter and Saturn, ice giants Uranus and Neptune. Gravity pulls planets towards the Sun while they move sideways, so they travel in orbits; closer planets move faster and have shorter years. It all formed about 4.6 billion years ago from a spinning cloud of gas and dust.
• Space Exploration – Space exploration means sending rockets, satellites, probes and people beyond Earth's air. Rockets rise by pushing gas down (action–reaction). At about 7.9 km/s sideways a craft keeps falling around Earth in orbit; at 11.2 km/s it escapes. Since 1957 space has been a place of rivalry and cooperation, and it gives us weather forecasts, navigation, communication and new science.
• History of Astronomy: How Our Picture of the Sky Changed – For thousands of years people thought Earth sat still at the centre and the sky turned round it. Careful watching of planets, then the telescope, showed a better picture: Earth and the other planets circle the Sun on ellipses, held by gravity. New ideas won because they explained more and could be tested.