Who this is for: Cambridge IGCSE Physics (0625) students who can name the planets but lose marks on orbital speed, why seasons happen, or confusing weight with mass in a space context.
What query it owns: how to understand and revise Earth and the Solar System in Cambridge IGCSE Physics.
Why this is safe: this page owns the Earth-and-Solar-System revision-guide angle, while Tutopiya’s Earth and the Solar System subtopic page owns the learning resource and the free Earth and Solar System quiz owns the practice.

Earth and the Solar System covers the Sun, planets, moons, orbits and how gravity holds the system together. Cambridge IGCSE Physics (0625) tests whether you can explain elliptical orbits, why planets closer to the Sun orbit faster, and what causes seasons and day/night. This guide covers the syllabus pathway and exam wording.

Key takeaways

• Gravity provides the centripetal force keeping planets and moons in orbit.
• Planets orbit the Sun in elliptical paths; closer planets have shorter orbital periods.
• Day and night = Earth’s rotation on its axis (~24 hours).
• Seasons = Earth’s tilted axis + orbit around the Sun — not distance from the Sun.
• The Moon orbits Earth; phases are caused by how much of the sunlit half we see.

What is Earth and the Solar System in Cambridge IGCSE Physics?

Earth and the Solar System is the Space Physics topic describing the Sun-centred model, planetary orbits, moons, comets and asteroids, and how gravitational attraction governs motion. You must explain seasons, eclipses at a basic level, and compare orbital speeds. Read the full notes on Tutopiya’s Earth and the Solar System subtopic page before attempting questions.

The core ideas you must master

Concept	Explanation	Common exam trap
Gravitational force	Attraction between masses; provides centripetal force for orbits	Saying “no gravity in space” (orbit = falling around)
Orbital speed	Closer to Sun → stronger gravity → faster orbit	Thinking outer planets orbit faster
Earth’s rotation	Spin on axis → day/night cycle	Confusing rotation with revolution
Earth’s revolution	Orbit around Sun (~365 days)	Blaming seasons on distance alone
Axial tilt (~23.5°)	Different hemispheres tilt toward Sun at different times → seasons	Seasons caused by distance from Sun

Solar System bodies — comparison table

Body	Orbits	Key feature
Planets	Sun (elliptical)	Eight planets; rocky inner, gas giants outer
Moons	Their planet	Earth’s Moon ~27 days; affects tides
Comets	Sun (elongated ellipse)	Icy body; tail points away from Sun
Asteroids	Sun (mostly belt)	Rocky; between Mars and Jupiter
Artificial satellites	Earth (or other planet)	Used for communication, weather, GPS

Earth and the Solar System in past-paper wording: command words that matter

Command word / phrase	What the question wants	Typical Earth/Solar System stem
Describe	Structure or sequence	”Describe how day and night occur.”
Explain	Cause and effect	”Explain why we have seasons.”
State	Short factual answer	”State what provides the centripetal force on a planet.”
Compare	Similarities and differences	”Compare the orbits of comets and planets.”
Suggest	Apply to context	”Suggest why geostationary satellites orbit at a fixed height.”

Worked exam-style stems (how to answer the wording)

1. “Explain why it is summer in the northern hemisphere when the North Pole tilts toward the Sun.” More direct sunlight / longer days / higher intensity of radiation on the northern hemisphere. Reward: links tilt to sunlight angle or duration, not distance.
2. “State what force keeps the Moon in orbit around Earth.” Gravitational attraction (gravity). Reward: gravity named as centripetal force provider.
3. “Describe the difference between a planet and a moon.” Planet orbits the Sun; moon orbits a planet. Reward: correct orbit centre for each.

When you can recognise the wording instantly, work the Earth and Solar System quiz and connect to Stars and the Universe.

How Earth and the Solar System connects to the rest of the syllabus

Space Physics links gravitational ideas from Mass and Weight and orbital motion concepts. The Cambridge IGCSE Physics resource hub links every Space Physics subtopic.

Common mistakes students make

• Explaining seasons by distance from the Sun (tilt is the cause).
• Confusing rotation (day/night) with revolution (year).
• Stating planets orbit in perfect circles only (ellipses).
• Saying the Moon produces its own light (it reflects sunlight).
• Forgetting gravity provides the centripetal force for orbits.

When you need more support

If orbital and seasons questions keep costing marks, work through the Earth and Solar System quiz, then get focused help from a Cambridge IGCSE Physics tutor.

Frequently asked questions

Is Earth and the Solar System hard in Cambridge IGCSE Physics? The facts are accessible; marks are lost on seasons explanations and confusing rotation with revolution.

What causes seasons? Earth’s axis tilted at ~23.5° so hemispheres receive different sunlight intensity and day length as Earth orbits the Sun.

Do planets orbit in circles? Elliptical orbits; the Sun is at one focus of the ellipse.

How do I revise Earth and the Solar System effectively? Draw Sun-Earth-Moon diagrams, explain seasons and day/night separately, then take the Earth and Solar System quiz.

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