Worksheet: Space physics (KS3)

Name or group: ____ Date: ______

Curriculum (England, KS3 Physics: Space physics):

• gravity force, weight = mass × gravitational field strength (g), different on other planets,
• our Sun as a star, other stars in our galaxy, other galaxies,
• the seasons and the Earth's tilt,
• the light year as a unit of astronomical distance.

In SpaceWise: Grown-ups > Start a lesson > KS3 Physics: Space physics. Then choose one of these:

• a mission: "Jump on the Moon", "Why do we have seasons?" or "How far is far?",
• a Science Lab experiment: "Weigh yourself" or "Light race",
• the Journey "Our Place in the Universe".

Part 1: Weight on other worlds (Science Lab "Weigh yourself")

Gravitational field strength at the surface:

1. A rock box has a mass of 20 kg. Work out its weight on each world. Use weight = mass × g.

2. The box goes to the Moon. Does its mass change? __

Part 2: The seasons (mission "Why do we have seasons?")

3. The Earth's axis is tilted. In June, which half of the Earth leans towards the Sun? __

4. Why are days in the UK longer in summer than in winter? __________

Part 3: Light years (mission "How far is far?", Science Lab "Light race")

Light travels at 299,792 km every second.

5. The Moon is 384,400 km from the Earth (on average). How long does its light take to reach us? ______ s

6. The Sun is 149,598,000 km from the Earth (on average). How long does sunlight take to reach us? __ s, which is about ____ minutes

7. What does one light year measure: a time or a distance? __

Part 4: Stars and galaxies (Journey "Our Place in the Universe")

8. Put these in order from smallest to largest: the Milky Way, the Sun, the Solar System, the Local Group.

9. Is the Sun a star or a planet? __

Answers for the teacher

1. Earth 196.2 N, Moon 32.4 N, Mars 74.6 N, Jupiter 462.4 N (20 kg × g). With the rounded g = 10 N/kg of the curriculum, the Earth weight is 200 N.
2. No. The mass stays 20 kg. Only the weight changes.
3. The Northern Hemisphere (the UK's half).
4. In summer the UK's half of the Earth leans towards the Sun. The Sun climbs higher and is above the horizon for longer each day.
5. About 1.3 s (384,400 ÷ 299,792).
6. About 499 s (149,598,000 ÷ 299,792), which is about 8 minutes.
7. A distance: how far light travels in one year.
8. The Sun, the Solar System, the Milky Way, the Local Group.
9. A star.

Sources: NASA planetary fact sheets for the Sun, Earth, Moon, Mars and Jupiter (https://nssdc.gsfc.nasa.gov/planetary/factsheet/), checked 3 October 2026. Speed of light in vacuum, 299,792,458 m/s (NIST, https://physics.nist.gov/cgi-bin/cuu/Value?c). National Curriculum in England: science programmes of study (GOV.UK).