IGCSE Physics 0625 · Topic 6

Space physics: past paper questions

240 real questionsasked in 9 of the last 10 exam series2020–2026usually: State, Calculate, Describe, Complete, Explain

Real questions on space physics

The newest 20 of 124 written questions, plus 116 multiple-choice. Open one to see it on the real paper.

0625/31 · May/June 2026 · Q11a(i)[3]
Four of the planets are labelled. Give the names of the other four planets. Write your answers in the boxes in Figure 11.1.
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0625/31 · May/June 2026 · Q11a(ii)[1]
Give the name of region X.
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0625/31 · May/June 2026 · Q11a(iii)[1]
State the name of the force that keeps the planets in orbit around the Sun.
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0625/31 · May/June 2026 · Q11b[4]
Describe the evidence that supports the idea of an expanding Universe. Use your ideas about redshift.
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0625/32 · May/June 2026 · Q10a[1]
State the approximate time taken for the Moon to orbit the Earth. Include the unit. time = unit
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0625/32 · May/June 2026 · Q10b[1]
Name the force that keeps the Moon in orbit around the Earth.
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0625/32 · May/June 2026 · Q10c[3]
A spacecraft on the Moon sends a radio signal to the Earth. The radio signal takes 1.28 s to travel from the Moon to the Earth. The speed of the radio signal is 3.0 × 10 8 m / s. Calculate the distance from the Moon to the Earth. distance = m
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0625/33 · May/June 2026 · Q10a[1]
State the approximate time taken for the Moon to orbit the Earth. Include the unit. time = unit
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0625/33 · May/June 2026 · Q10b[1]
Name the force that keeps the Moon in orbit around the Earth.
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0625/33 · May/June 2026 · Q10c[3]
A spacecraft on the Moon sends a radio signal to the Earth. The radio signal takes 1.28 s to travel from the Moon to the Earth. The speed of the radio signal is 3.0 × 10 8 m / s. Calculate the distance from the Moon to the Earth. distance = m
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0625/41 · May/June 2026 · Q9b(ii)[1]
The Sun is a star in the Milky Way galaxy. State the approximate diameter of the Milky Way. Give your answer in light‑years. diameter = light‑years
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0625/41 · May/June 2026 · Q9c(i)[1]
State what is meant by redshifted.
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0625/41 · May/June 2026 · Q9c(ii)[2]
Explain how redshift supports the Big Bang Theory. Question 10 is on the back page. Permission to reproduce items where third‑party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (Cambridge University Press & Assessmen...
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0625/43 · May/June 2026 · Q11a[3]
The Sun is an example of a stable star. Describe the process that releases energy in the Sun.
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0625/42 · February/March 2026 · Q11b(ii)[5]
Show that one Saturn year is approximately equal to 30 Earth years. Saturn is 1.4 × 10 12 m from the Sun. (ii)
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0625/31 · October/November 2025 · Q11a[1]
State why the gravitational field strength at the surface of the Earth is greater than the gravitational field strength at the surface of Mars.
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0625/31 · October/November 2025 · Q11b[3]
State the names of the four gaseous planets further from the Sun than Mars. List the planets in order of increasing distance from the Sun. increasing distance from the Sun
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0625/31 · October/November 2025 · Q11c[3]
A device on the surface of Mars sends a radio wave to the Earth. The distance from Mars to the Earth is 1.3 × 10 11 m. The speed of the radio wave is 3.0 × 10 8 m / s. Calculate the time taken for the radio wave to travel from Mars to the Earth. time taken = s
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0625/32 · October/November 2025 · Q10a[1]
Complete these sentences about the formation of the Solar System. (i) Planets were formed from interstellar clouds of gas and (ii) The interstellar clouds were pulled together by the force of (iii) The rotation of material in the interstellar clouds formed an accretion
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0625/32 · October/November 2025 · Q10b[2]
State one piece of evidence that supports the Big Bang Theory and explain how this evidence supports the Big Bang Theory. evidence explanation (b) The Big Bang Theory is a possible description of the beginning of the Universe.
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What examiners said

Comprehensive responses • Some candidates set out a proof clearly and logically, outlining the steps which show that a Saturn year is 29 years (to two significant figures) and that therefore the statement in the question was true. Limited responses • Some candidates used v = s / t instead of rearranging the equation for orbital speed to make T the subject. • A few candidates attempted a calculati...
— Examiner report, February/March 2026, 0625/42 Q11(b)(ii) (Cambridge)

A large number of candidates correctly stated that the dashed line was the normal. However, a variety of incorrect answers were also seen, such as ‘mirror line’, ‘refraction’ or ‘reflection’.
— Examiner report, May/June 2025, 0625/31 Q6(a)(i) (Cambridge)

Almost all candidates correctly identified the galaxy containing our Solar System as the Milky Way galaxy.
— Examiner report, May/June 2025, 0625/31 Q11(a)(ii) (Cambridge)

Practise this topic

Answer these questions online and get each one marked against the official mark scheme, with what you missed and how to fix it.

Practise space physics

In the syllabus

6.1.1 The Earth

Know that the Earth is a planet that rotates on its axis, which is tilted, once in approximately 24 hours, and use this to explain observations of the apparent daily motion of the Sun and the periodic cycle of day and night
Know that the Earth orbits the Sun once in approximately 365 days and use this to explain the periodic nature of the seasons
Know that it takes approximately one month for the Moon to orbit the Earth and use this to explain the periodic nature of the Moon’s cycle of phases
Define average orbital speed from the equation v = 2πr / T where r is the average radius of the orbit and T is the orbital period; recall and use this equation

6.1.2 The Solar System

Describe the Solar System as containing: (a) one star, the Sun (b) the eight named planets and know their order from the Sun (c) minor planets that orbit the Sun, including dwarf planets such as Pluto and asteroids in the asteroid belt (d) moons, that orbit the planets (e) smaller Solar System bodies, including comets and natural satellites
Know that, in comparison to each other, the four planets nearest the Sun are rocky and small and the four planets furthest from the Sun are gaseous and large, and explain this difference by referring to an accretion model for Solar System formation, to include: (a) the model’s dependence on gravity (b) the presence of many elements in interstellar clouds of gas and dust (c) the rotation of material in the cloud and the formation of an accretion disc
Know that the strength of the gravitational field (a) at the surface of a planet depends on the mass of the planet (b) around a planet decreases as the distance from the planet increases
Calculate the time it takes light to travel a significant distance such as between objects in the Solar System
Know that the Sun contains most of the mass of the Solar System and this explains why the planets orbit the Sun
Know that the force that keeps an object in orbit around the Sun is the gravitational attraction of the Sun
Know that planets, minor planets and comets have elliptical orbits, and recall that the Sun is not at the centre of the elliptical orbit, except when the orbit is approximately circular
Analyse and interpret planetary data about orbital distance, orbital duration, density, surface temperature and uniform gravitational field strength at the planet’s surface
Know that the strength of the Sun’s gravitational field decreases and that the orbital speeds of the planets decrease as the distance from the Sun increases
Know that an object in an elliptical orbit travels faster when closer to the Sun and explain this using the conservation of energy

6.2.1 The Sun as a star

Know that the Sun is a star of medium size, consisting mostly of hydrogen and helium, and that it radiates most of its energy in the infrared, visible light and ultraviolet regions of the electromagnetic spectrum
Know that stars are powered by nuclear reactions that release energy and that in stable stars the nuclear reactions involve the fusion of hydrogen into helium

6.2.2 Stars

State that: (a) galaxies are each made up of many billions of stars (b) the Sun is a star in the galaxy known as the Milky Way (c) other stars that make up the Milky Way are much further away from the Earth than the Sun is from the Earth (d) astronomical distances can be measured in light-years, where one light-year is the distance travelled in (the vacuum of) space by light in one year
Know that one light-year is equal to 9.5 × 10¹⁵ m
Describe the life cycle of a star: (a) a star is formed from interstellar clouds of gas and dust that contain hydrogen (b) a protostar is an interstellar cloud collapsing and increasing in temperature as a result of its internal gravitational attraction (c) a protostar becomes a stable star when the inward force of gravitational attraction is balanced by an outward force due to the high temperature in the centre of the star (d) all stars eventually run out of hydrogen as fuel for the nuclear reaction (e) most stars expand to form red giants and more massive stars expand to form red supergiants when most of the hydrogen in the centre of the star has been converted to helium (f) a red giant from a less massive star forms a planetary nebula with a white dwarf star at its centre (g) a red supergiant explodes as a supernova, forming a nebula containing hydrogen and new heavier elements, leaving behind a neutron star or a black hole at its centre (h) the nebula from a supernova may form new stars with orbiting planets

6.2.3 The Universe

Know that the Milky Way is one of many billions of galaxies making up the Universe and that the diameter of the Milky Way is approximately 100 000 light-years
Describe redshift as an increase in the observed wavelength of electromagnetic radiation emitted from receding stars and galaxies
Know that the light emitted from distant galaxies appears redshifted in comparison with light emitted on the Earth
Know that redshift in the light from distant galaxies is evidence that the Universe is expanding and supports the Big Bang Theory
Know that microwave radiation of a specific frequency is observed at all points in space around us and is known as cosmic microwave background radiation (CMBR)
Explain that the CMBR was produced shortly after the Universe was formed and that this radiation has been expanded into the microwave region of the electromagnetic spectrum as the Universe expanded
Know that the speed v at which a galaxy is moving away from the Earth can be found from the change in wavelength of the galaxy’s starlight due to redshift
Know that the distance d of a far galaxy can be determined using the brightness of a supernova in that galaxy
Define the Hubble constant H₀ as the ratio of the speed at which the galaxy is moving away from the Earth to its distance from the Earth; recall and use the equation H₀ = v / d
Know that the current estimate for H₀ is 2.2 × 10⁻¹⁸ per second
Know that the equation d / v = 1 / H₀ represents an estimate for the age of the Universe and that this is evidence for the idea that all the matter in the Universe was present at a single point

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