Topic 7 – Astronomy — Edexcel GCSE Physics
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Topic 7 – Astronomy explained
This item tests recall of two linked facts: the names of the eight planets and their order by increasing distance from the Sun.
Read the full explanation
Learn the sequence as a chain starting closest to the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. A memory sentence whose words begin with the same letters can anchor the order, but check each name against the chain rather than trusting the sentence alone. Note that the Sun sits at the centre of this ordering, so distance is measured outward from it, and that Pluto is not one of the eight planets. In a multiple-choice question, read all options before choosing, then confirm the option matches both the names and the direction of ordering asked for.
Your focus
- Name the eight planets of the Solar System
- Arrange the eight planets in order of increasing distance from the Sun
- Identify which bodies do not belong in the list of eight planets
Topic 7 – Astronomy exam tips
Marking Points
- Selects the option listing Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune in that order from the Sun
- Identifies Mercury as the planet closest to the Sun and Neptune as the most distant of the eight
- Rejects any option that inserts Pluto or another body into the sequence of eight planets
- Recognises that the ordering is by increasing distance outward from the Sun, not by size or mass
Examiner Tips
- 💡Write the eight names in order from memory before looking at the options, then match your list to the choices
- 💡Check the direction of the ordering the question asks for, since a reversed list is a common distractor
- 💡Eliminate any option containing a body that is not one of the eight planets before comparing the rest
Common Mistakes
- Places Mars before Earth in the order; correct this by fixing Earth as third from the Sun and Mars as fourth
- Includes Pluto as a ninth planet; correct this by listing only the eight planets and treating Pluto as a dwarf planet outside the sequence
- Orders the planets by size instead of distance; correct this by ranking from Mercury outward to Neptune
- Starts the sequence at Earth as though it were closest to the Sun; correct this by beginning with Mercury