IGCSE 0625 / Section 6.2.1 / Core

Our local star.

The Sun feels unique because it is ours, but it is a fairly ordinary star, one of billions. It shines not by burning but by fusing hydrogen into helium deep in its core, flooding the Solar System with energy.

The key idea

The Sun is a medium-sized star made mostly of hydrogen and helium. It releases energy by the nuclear fusion of hydrogen into helium in its core, and it is the main source of energy for the Solar System.

Definition · learn the exact words

The Sun is a star, a medium-sized star made mostly of hydrogen and helium. It releases energy by the nuclear fusion of hydrogen into helium.

energy source: fusion of hydrogen into helium

The Sun is the main source of energy for the Solar System, and just one of billions of stars.

Section 01

Look at the Sun.

See the Sun as a star powered by fusion in its core.

Stage 1 · Learn

Check the sun

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

Quick check+10 XP

The Sun is best described as...

Quick check+10 XP

The Sun is made mostly of...

Quick check+10 XP

The Sun releases its energy by...

Quick check+10 XP

In the Sun, hydrogen is fused into...

Section 02

An ordinary star.

The Sun is medium-sized, made of light elements, and shines by fusion.

Examiner trap

The Sun shines by nuclear fusion, joining hydrogen nuclei into helium, not by burning like a fire. It is a fairly ordinary, medium-sized star among billions of others.

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

Compared with other stars, the Sun is...

Exam style+20 XP

The energy radiated by the Sun comes from...

Exam style+20 XP

For the Solar System, the Sun is the...

Skill unlocked

The sun, mastered.

The Sun as a star is mapped. Keep the chain going.

-Rank -Level -Score -Topics
Go deeper · practice
Six original Cambridge-style questions
The Sun as a medium-sized star of hydrogen and helium that releases energy by fusion. 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 the sun.
Start the unit challenge →