A supernova is one stage in the life cycle of a massive star. Explain what a supernova is and describe the role it plays in distributing elements throughout the universe.

OCR GCSE Physics A: Gateway Science (J249) — P6.3 Astronomy · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Astronomers studying a distant galaxy have detected the sudden dramatic brightening of a single star, followed by the appearance of a slowly expanding cloud of gas and heavy elements spreading outward from where the star once was.

Model answer (4 marks)

A supernova is the explosion of a massive star.

During the star’s life, fusion reactions build heavy nuclei from lighter ones.

When the star explodes, the fusion‑produced heavy elements are expelled into space.

The expanding gas cloud becomes a nebula, which can later collapse to form new stars and planets that contain these heavier elements.

Examiner tips

Use the word "explosion" to show understanding of a supernova.
Mention fusion as the source of heavy elements.
Explain that the explosion spreads these elements.
Show that the expelled gas can form a nebula that seeds new stars and planets.

Common mistakes

Confusing a supernova with a normal star death; not stating it is an explosion.
Failing to mention fusion as the source of heavy elements.
Not linking the expanding cloud to future star/planet formation.

Mark scheme (4 marks)

A supernova is the explosion of a massive star
Heavy/larger nuclei are produced inside the star by fusion reactions during the star's lifetime
The supernova explosion distributes/spreads these elements (created by fusion) throughout the universe
The expanding cloud of gas and elements observed may form a new nebula, which can eventually lead to the formation of new stars and planets containing these heavier elements

Key terms in this question

supernova · massive star · elements