1. 1
   An astronomy club is building a scale model of the Solar System for a school open evening, arranging balls of different sizes to represent the Sun, the eight planets, and some of the minor planets and moons.

   (a)

   They place a large ball to represent the Sun at the centre of the model. What is the main reason the Sun is placed at the centre of the Solar System model?

   [1 mark]

   • AThe Sun contains most of the mass of the Solar System, so its gravity keeps the planets in orbit around it
   • BThe Sun is the coldest object in the Solar System
   • CThe planets are held in place by magnetic forces from the Sun
   • DThe Sun does not move at all in the Universe

   (b)

   The club arranges eight small balls in order of their distance from the Sun to represent the planets. Which of these is the correct order of the four planets nearest the Sun?

   [1 mark]

   • AMercury, Earth, Venus, Mars
   • BMercury, Venus, Earth, Mars
   • CEarth, Venus, Mercury, Mars
   • DMars, Earth, Venus, Mercury

   (c)

   The club also wants to include a small object representing Pluto and a scattering of tiny rocks representing the asteroid belt in their model. State what type of Solar System object Pluto is classified as, and state where the asteroid belt is generally located.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A science writer is preparing an article explaining how the Solar System is thought to have formed from a rotating cloud of gas and dust, according to the accretion model, and why the inner and outer planets differ so much in composition.

   (a)

   A science writer explains that the four planets closest to the Sun (Mercury, Venus, Earth and Mars) are quite different in composition from the four planets furthest from the Sun (Jupiter, Saturn, Uranus and Neptune). How would the writer best describe this difference?

   [1 mark]

   • AAll eight planets are made of the same rocky material and are similar in size
   • BThe four inner planets are gaseous and relatively large, while the four outer planets are rocky and relatively small
   • CThe four inner planets are rocky and relatively small, while the four outer planets are gaseous and relatively large
   • DThe four inner planets have no moons, while the four outer planets each have hundreds of moons

   (b)

   According to the accretion model, what causes the rotating cloud of gas and dust to flatten into a disc-shaped structure as the Solar System forms?

   [1 mark]

   • AElectrical charge building up on the dust particles
   • BThe heat given off by nearby stars
   • CChemical reactions between different gases
   • DThe rotation of the collapsing cloud

   (c)

   State what an interstellar cloud of gas and dust, from which the Solar System formed, is known to contain, and explain briefly the role gravity plays in causing such a cloud to begin collapsing.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A team of astronomers is analysing orbital data for Jupiter and comparing planetary data, including orbital distance, orbital duration and gravitational field strength, across the Solar System.

   (a)

   A team of astronomers is analysing data on Jupiter and comparing it with Earth. Jupiter has an average orbital radius of 7.78 x 10^11 m and an orbital period of 4333 days, while Earth has an average orbital radius of 1.50 x 10^11 m and an orbital period of 365 days. Using the equation for average orbital speed, calculate Jupiter's average orbital speed in metres per second, showing your working, and state whether this is greater or smaller than Earth's average orbital speed.

   [3 marks]

   (b)

   The team also analyses a table showing the gravitational field strength at the surface of several planets: Mercury (3.7 N/kg), Earth (9.8 N/kg), Jupiter (24.8 N/kg) and Neptune (11.2 N/kg). Explaining your reasoning, suggest why Jupiter has a much higher surface gravitational field strength than Mercury, and suggest why Neptune, despite being much further from the Sun and much larger in diameter than Earth, does not have a dramatically higher surface gravitational field strength than Earth.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A space agency is producing an educational documentary explaining the accretion model of Solar System formation and how it accounts for the differences between the rocky inner planets and the gaseous outer planets.

   (a)

   Describe, in detail, how the Solar System is thought to have formed according to the accretion model, starting from an interstellar cloud of gas and dust, and explain why this model predicts that the four planets nearest the Sun should be rocky and relatively small, while the four planets furthest from the Sun should be gaseous and relatively large.

   [6 marks]

   (b)

   The documentary also includes a segment analysing a table of planetary data showing orbital distance, orbital duration, density and surface temperature for several planets, to help viewers understand broad patterns across the Solar System. Explain, with reasons, the general trends you would expect to see across the eight planets for orbital duration and surface temperature as distance from the Sun increases, and explain why density generally follows a different pattern, being higher for the rocky inner planets than for the gaseous outer planets.

   [6 marks]

   Total for question 4: 12 marks

End of questions