IGCSE 0625 / Section 6.1.2 / Core

Built from a cloud.

Long before the planets, there was only a vast, cold cloud of gas and dust. Gravity did the rest, pulling it inward until a star ignited at the heart and the leftovers clumped, grain by grain, into worlds.

The key idea

The Solar System formed from a cloud of gas and dust that collapsed under gravity. Most of the mass gathered into the Sun at the centre, while the remaining material in a spinning disc clumped together by accretion to build the planets.

Definition · learn the exact words

The Solar System formed from a cloud of gas and dust that collapsed under gravity. Most of the mass formed the Sun; the rest clumped together by accretion to form the planets.

gravity pulls the cloud together; accretion builds the planets

The leftover material formed a spinning disc around the young Sun.

Section 01

Collapse the cloud.

Let gravity pull the cloud together and watch the Sun and planets take shape.

Stage 1 · Learn

Check formation

Four quick checks. Each correct answer earns XP and lights this skill on your star map.

Quick check+10 XP

The Solar System formed from a cloud of...

Quick check+10 XP

The cloud collapsed because of...

Quick check+10 XP

Most of the mass of the cloud formed the...

Quick check+10 XP

The planets grew by a process called...

Section 02

Sun first, then planets.

Gravity makes the Sun from most of the mass, and accretion builds the planets from the rest.

Examiner trap

It was gravity that pulled the cloud of gas and dust together, and the planets grew by accretion, smaller clumps sticking together into larger bodies, in the disc around the young Sun.

Stage 2 · Exam

Exam-style questions

Unlocks once the four checks above are done. Worth more XP, written in the style of Paper 2.

Finish the four checks above to unlock the exam questions
Exam style+20 XP

What force caused the cloud of gas and dust to collapse?

Exam style+20 XP

During the formation of the Solar System, the planets formed by...

Exam style+20 XP

Most of the mass of the original cloud ended up in the...

Skill unlocked

Formation, mastered.

The formation of the Solar System is mapped. Keep the chain going.

-Rank -Level -Score -Topics
Go deeper · practice
Six original Cambridge-style questions
The collapse of a gas-and-dust cloud under gravity, the Sun forming from most of the mass, and planets growing by accretion. Attempt each, then reveal the worked solution.
Stage 3 · master the unit
Space physics challenge
Mixed questions across the whole unit, each one worth XP. Start this only when you feel confident across every topic in the unit, not just formation.
Start the unit challenge →