Solar System 02

This KS3 Science quiz takes a further look at the Solar System. The principal component of the Solar System is the Sun. The Sun is our nearest star and is almost 1.4 million kilometres in diameter. It contains 99.86 percent of the System's known mass and its gravity keeps all the planets, asteroids (minor planets) and comets in orbit.

The orbits of planets are nearly circular but the orbits of minor planets and comets can be very oval in shape. The planets have gravitational fields too and most of them have attracted smaller satellites which orbit the planet and not the Sun. We often refer to these natural satellites as moons (or Moon with a capital M in the case of the Earth). As the Earth moves along its orbit, the Sun seems to move relative to the horizon.

When Britain is experiencing winter, the Earth is in fact closer to the Sun than in summer, but the Sun appears low in the sky, shadows are longer and there are more hours of darkness than daylight. The Earth also spins on its axis once every 24 hours. This means that the Sun appears to move across the sky every day. Before the 17^th century, people thought that the Earth was the centre of everything and that it was the Sun and stars that were moving. They invented many weird and wonderful explanations such as the Sun, stars and planets being fixed to 'crystal spheres' and some of the ancient civilisations thought that it was a new and different Sun that rose every day!