The Solar System (Oxford AQA IGCSE Physics)
Revision Note
Written by: Ann Howell
Reviewed by: Caroline Carroll
The Solar System
The Sun lies at the centre of the Solar System
The Sun is a medium-sized star
There are 8 planets and an unknown number of dwarf planets which orbit the Sun
The gravitational field around planets is strong enough to pull in all nearby objects, except for natural satellites
The gravitational field around a dwarf planet is not strong enough to pull in nearby objects
There are 4 rocky planets: Mercury, Venus, Earth and Mars
There are 4 gas planets: Jupiter, Saturn, Uranus and Neptune
Some planets have moons which orbit them
Moons are an example of natural satellites
Artificial satellites are man-made and can orbit any object in space
The International Space Station (ISS) orbits the Earth and is an example of an artificial satellite
Asteroids and comets also orbit the sun
An asteroid is a small rocky object which orbits the Sun
The asteroid belt lies between Mars and Jupiter
Comets are made of dust and ice and orbit the Sun in a different orbit to those of planets
The ice melts when the comet approaches the Sun and forms the comet’s tail
Objects in our solar system
Examiner Tips and Tricks
You need to know the order of the 8 planets in the solar system and to be able to compare their relative size and motion. The following mnemonic gives the first letter of each of the planets to help you recall them:
My Very Excellent Mother Just Served Us Noodles
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
Before Pluto was reclassified as a dwarf planet in 2006, 'my very excellent mother' used to 'serve us' 'Nine Pizzas' and you can still use that one to remember the 'old' solar system!
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