Nearest star to Sun: Proxima Centauri — 4.2 light-years away.
Life cycle of stars
All stars: formed from clouds of gas and dust (nebula) → gravitational collapse → protostar → main sequence star (hydrogen fusion, balance of gravity vs radiation pressure).
Small stars (like Sun): main sequence → red giant (He fusion) → planetary nebula → white dwarf → black dwarf.
Large stars: main sequence → red supergiant → supernova (explosive collapse) → neutron star OR black hole (if very massive).
Supernova: heavy elements (beyond iron) formed and dispersed through universe.
Our Sun: currently main sequence (~halfway through its ~10 billion year life).
Formation of the Solar System
Formed ~4.6 billion years ago from a rotating cloud of gas and dust (solar nebula).
Gravity caused collapse → most mass collected at centre → Sun formed.
Remaining material flattened into a disc. Material clumped (accretion) → planets.
Rocky (inner) planets: formed close to Sun where temperatures were too high for gas to remain.
Gas giants: formed further out where ices and gases could also accrete.
⚡ Show all working — the AI marks against the AQA mark scheme. Method marks awarded for correct working even if the final answer is wrong.
1 markMain sequence starAQA 8463 style
What process releases energy in a main sequence star like the Sun?
A Nuclear fission of uranium in the core
B Combustion of hydrogen in the core
C Nuclear fusion of hydrogen into helium in the core
D Gravitational collapse continuously releasing energy
4 marksStellar life cycleAQA 8463 P2 style
Describe the life cycle of a star similar to our Sun, from nebula to final state. (4 marks)
Hint: Five stages in order: nebula → protostar → main sequence → red giant → planetary nebula → white dwarf. Give brief explanation of each transition.
+40 XP
1 markLarge star endpointAQA 8463 style
A star much more massive than the Sun will eventually become a:
A White dwarf
B Red giant then planetary nebula
C Supernova, then either a neutron star or black hole
D Double star system
3 marksFormation of solar systemAQA 8463 style
Explain why the inner planets are rocky and the outer planets are gas giants. (3 marks)
Hint: Key concept: temperature gradient. Close to Sun = too hot for gases/ices to stay → rocky planets. Far from Sun = cold enough for gases/ices → gas giants.