10 free IGCSE Physics Space Physics questions written in the style of Cambridge Physics papers: 1 multiple-choice and 9 structured, each with its answer and mark scheme. 4 of them are A* challenge questions, built to catch the mistakes strong students still make.
This topic covers Earth & the Solar System, Stars & the Universe. Work through the questions below, then generate a full Space Physics paper with a fresh set every time.
Generate a full Space Physics paper →A galaxy is moving away from the Earth at 6600 km/s. The Hubble constant H0 is 2.2 × 10−18 per second.
What is the distance from the Earth to the galaxy?
Answer: D
Light from the Sun takes about 500 s to reach the Earth. The speed of light is 3.0 × 10⁸ m/s.
Calculate the distance from the Sun to the Earth.
State what force keeps the planets in orbit around the Sun.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | 1.5 × 10¹¹ m d = vt = 3.0 × 10⁸ × 500 C1 1.5 × 10¹¹ m A1 | 2 |
| (b) | gravity the gravitational attraction of the Sun B1 | 1 |
Stars much more massive than the Sun follow a different life cycle.
Describe the life cycle of a massive star after the main sequence.
Explain how the elements heavier than iron were formed.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | red supergiant → supernova → neutron star or black hole red supergiant B1 supernova B1 neutron star or black hole B1 | 3 |
| (b) | in supernova explosions in supernovae B1 | 1 |
A satellite moves in a circular orbit of radius 4.22 × 107 m around the Earth with a period of 24 hours.
Calculate the orbital speed of the satellite.
State the direction of the resultant force on the satellite, and explain why its speed stays constant even though a force acts on it.
Astronomers measure the light from a distant galaxy. The galaxy is 6.0 × 1024 m away and is moving away at 1.4 × 107 m/s.
Calculate the Hubble constant H0 from these data.
Use your answer to (c) to estimate the age of the Universe, in years.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | 3070 m/s v = 2πr ÷ T with T in seconds C1 3070 A1 | 2 |
| (b) | Towards the centre of the Earth; the force is perpendicular to the motion so it changes direction, not speed towards the centre of the Earth/orbit B1 force perpendicular to velocity, so no work done / only direction changes B1 | 2 |
| (c) | 2.3 × 10−18 /s H0 = v ÷ d C1 2.3 × 10−18 A1 | 2 |
| (d) | 1.4 × 1010 years age ≈ 1 ÷ H0 in seconds C1 ÷ 3.15 × 107 s per year = 1.4 × 1010 A1 | 2 |
This question is about the Earth and the Moon.
State the approximate time taken for the Earth to orbit the Sun and for the Moon to orbit the Earth.
Explain why the Moon shows phases.
The Moon orbits at an average distance of 3.84 × 108 m and takes 27.3 days to complete one orbit. Calculate its orbital speed.
Light from the Moon takes about 1.3 s to reach the Earth. Calculate the distance to the Moon from this time.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | 365 days (one year); about one month (27–29 days) about 365 days B1 about one month / 27–29 days B1 | 2 |
| (b) | Moon reflects sunlight; half always lit; we see different amounts of the lit half as it orbits the Moon does not emit light, it reflects sunlight B1 half of the Moon is always lit by the Sun B1 as it orbits the Earth we see different proportions of the lit half B1 | 3 |
| (c) | 1020 m/s T = 27.3 × 24 × 3600 = 2.36 × 106 s C1 v = 2πr/T C1 1020 m/s A1 | 3 |
| (d) | 3.9 × 10⁸ m d = 3.0 × 10⁸ × 1.3 C1 3.9 × 10⁸ m A1 | 2 |
This question is about orbits and the expanding Universe.
A planet orbits the Sun at an average distance of 2.9 × 109 km. It takes 84 years to complete one orbit. Calculate its average orbital speed in m/s. [1 year = 3.16 × 10⁷ s]
Explain why the orbital speed of a comet changes as it moves along its elliptical orbit.
A distant galaxy is 1.0 × 1024 m from Earth. The Hubble constant is 2.2 × 10⁻¹⁸ s⁻¹. Calculate the speed at which the galaxy is moving away from Earth.
Explain how the observation of redshift supports the Big Bang Theory.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | 6860 m/s r = 2.9 × 1012 m and T = 2.65 × 109 s C1 v = 2πr/T C1 6860 m/s A1 | 3 |
| (b) | faster closer to the Sun; gravitational potential energy converted to kinetic energy it speeds up as it approaches the Sun and slows as it moves away B1 gravitational potential energy is converted to kinetic energy (and back), total constant B1 | 2 |
| (c) | 2.20 × 106 m/s v = H₀d C1 2.20 × 106 m/s A1 | 2 |
| (d) | light from distant galaxies is redshifted; more distant galaxies more redshift so receding faster; universe expanding from a point light from distant galaxies has longer wavelengths than expected (redshift), so they are moving away B1 more distant galaxies have greater redshift, so the Universe is expanding (from a single point) B1 | 2 |
This question is about the Sun and other stars.
State the regions of the electromagnetic spectrum in which most of the Sun’s energy is emitted.
Define a light-year.
A star is 640 light-years away. Calculate this distance in metres. (1 light-year = 9.5 × 10¹⁵ m)
Explain why looking at a distant star means looking into the past.
Describe how a star like the Sun forms from a cloud of gas and dust.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | infrared, visible and ultraviolet Any 2 of: infrared; visible light; ultraviolet B2 | 2 |
| (b) | distance travelled by light in one year the distance travelled by light in (a vacuum in) one year B1 | 1 |
| (c) | 6.1 × 1018 m 640 × 9.5 × 10¹⁵ C1 6.1 × 1018 m A1 | 2 |
| (d) | light took years to reach us; we see the star as it was the light we see left the star many years ago, so we see it as it was then B1 | 1 |
| (e) | gravity pulls dust and gas together; protostar heats up; fusion starts, stable star gravity pulls the gas and dust together (nebula) B1 the protostar becomes hotter as it collapses B1 when hot enough nuclear fusion starts and it becomes a stable main-sequence star B1 | 3 |
Light from distant galaxies shows redshift.
State what is meant by redshift.
Explain how redshift supports the Big Bang theory.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | increase in observed wavelength the observed wavelength of light is longer than the emitted wavelength B1 | 1 |
| (b) | galaxies moving away; universe expanding almost all galaxies show redshift, so they are moving away from us B1 the further away, the greater the redshift, so the Universe is expanding B1 | 2 |
This question is about stars and the Universe.
Describe the life cycle of a star much more massive than the Sun, after it leaves the main sequence.
State the energy source of a main-sequence star and explain why it is stable.
Light from distant galaxies is red-shifted. Explain what this means and what it shows.
State what is meant by cosmic microwave background radiation (CMBR) and explain how it supports the Big Bang theory.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | red supergiant; supernova; neutron star or black hole becomes a red supergiant B1 explodes as a supernova B1 leaving a neutron star or a black hole B1 | 3 |
| (b) | nuclear fusion of hydrogen; outward pressure balances gravity nuclear fusion of hydrogen into helium B1 the outward pressure from the energy released balances the inward pull of gravity B1 | 2 |
| (c) | wavelength increased; galaxy moving away the observed wavelength is longer than the emitted wavelength B1 the galaxy is moving away from us B1 | 2 |
| (d) | microwave radiation from all directions; remnant of early hot Universe, stretched by expansion microwave radiation detected from all directions in space B1 it is radiation from the hot early Universe, stretched to longer wavelengths by expansion B1 | 2 |
The Earth orbits the Sun and the Moon orbits the Earth.
State the approximate time for the Moon to orbit the Earth.
Explain why we have day and night.
Explain why we have seasons.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | about one month about 27–28 days (one month) B1 | 1 |
| (b) | Earth rotates on its axis the Earth rotates on its axis once every 24 hours B1 | 1 |
| (c) | tilted axis the Earth’s axis is tilted B1 so different hemispheres face the Sun more directly at different times of the year B1 | 2 |
In the 0625 syllabus, Space Physics covers Earth & the Solar System, Stars & the Universe.
This page has 10 Space Physics questions with answers. For more, the free generator on mentorriyaz.in builds a new Space Physics paper with a full mark scheme each time you click.
Riyaz Shaikh has mentored IGCSE, IB and A Level students for 15+ years, one-on-one, online and in Mumbai. The hardest questions on this site are the ones he uses to find a student's weak points.
Meet Riyaz →Original Cambridge-style practice questions written for mentorriyaz.in. These are not Cambridge past paper questions, and this site is not affiliated with or endorsed by Cambridge University Press & Assessment. Updated 2026-11-04. Paper generator · mentorriyaz.in