Space physics Banker

1. (a) What is a light-year?A the time light takes to reach the Earth from the SunB the distance travelled by light in a vacuum in one yearC the time for the Earth to orbit the SunD the brightness of a star seen from one year away [1]

1. (a) Which two elements make up most of the Sun?A hydrogen and heliumB hydrogen and oxygenC helium and carbonD iron and nickel [1]

1. (a) The Sun is described as a medium-sized star. State the source of its energy. [2]
2. (b) Name the three regions of the electromagnetic spectrum in which the Sun emits most of its energy. [2]
3. (c) State one reason why the Sun appears much brighter than other stars. [1]

1. (a) State what is meant by a galaxy. [1]
2. (b) Name the galaxy that contains the Solar System. [1]
3. (c) Show that one light-year is about 9.5 × 10¹⁵ m. Take one year as 365.25 days and the speed of light as 3.0 × 10⁸ m/s. [2]
4. (d) The diameter of the Milky Way is about 100 000 light-years. State what this tells you about the time light takes to cross it. [1]

1. (a) Put these stages in the life cycle of a star like the Sun in the correct order: red giant, interstellar cloud of dust and gas, white dwarf, protostar, stable star, planetary nebula. [3]
2. (b) State the main element present in the cloud from which a star forms. [1]
3. (c) State the force that pulls the cloud together to form a protostar. [1]

1. (a) A star with a mass about twenty times that of the Sun reaches the end of its stable life. Which sequence is correct?A red giant → planetary nebula → white dwarfB red supergiant → supernova → neutron star or black holeC white dwarf → red giant → supernovaD protostar → red supergiant → white dwarf [1]

1. (a) A stable star stays the same size for billions of years. Explain why, in terms of the forces acting. [2]
2. (b) Describe what happens to a star like the Sun when most of the hydrogen in its core has been used. [2]
3. (c) Describe what remains at the end of the life of a star like the Sun. [2]

Proxima Centauri is the nearest star to the Sun, at a distance of 4.2 light-years.

1. (a) Calculate the distance to Proxima Centauri in metres. One light-year = 9.46 × 10¹⁵ m. [2]
2. (b) State how long ago the light now reaching us from Proxima Centauri left the star. [1]
3. (c) A newspaper says a star 'might no longer exist even though we can see it'. Explain how this can be true for a very distant star. [2]

1. (a) State what is meant by redshift. [2]
2. (b) Light from almost all distant galaxies shows redshift. State two conclusions about the Universe. [2]
3. (c) Explain how redshift supports the Big Bang theory. [1]
4. (d) Name one other piece of evidence for the Big Bang theory. [1]

New stars are forming in the Orion Nebula, a huge cloud of dust and gas.

1. (a) Describe how a protostar forms from an interstellar cloud. [2]
2. (b) Explain why the protostar becomes hotter as it contracts. [2]
3. (c) State what must happen in the protostar for it to become a stable star. [1]
4. (d) Some interstellar clouds contain elements such as iron and carbon as well as hydrogen. Suggest where these heavier elements came from. [1]

An astronomy club in Karachi studies four stable stars:star P: 0.8 times the mass of the Sunstar Q: 1.0 times the mass of the Sunstar R: 12 times the mass of the Sunstar S: 30 times the mass of the Sun

1. (a) Identify which stars will end as white dwarfs. [1]
2. (b) State the stage that star R reaches after it leaves the stable stage. [1]
3. (c) Identify which star is most likely to end as a black hole and give a reason. [2]
4. (d) Describe what remains after star R explodes as a supernova. [2]

1. (a) The Hubble constant is 2.2 × 10⁻¹⁸ per second. A galaxy is 1.0 × 10²⁴ m from the Earth. What is the speed at which it is moving away from the Earth?A 2.2 × 10⁶ m/sB 4.5 × 10⁴¹ m/sC 4.5 × 10⁻⁷ m/sD 2.2 × 10⁻⁴² m/s [1]

Astronomers measure the redshift of a distant galaxy and find it is moving away from the Earth at 1.5 × 10⁷ m/s. The Hubble constant H₀ = 2.2 × 10⁻¹⁸ per second.

1. (a) Calculate the distance to the galaxy in metres. [2]
2. (b) Convert this distance into light-years. One light-year = 9.46 × 10¹⁵ m. [1]
3. (c) The quantity 1/H₀ gives an estimate of the age of the Universe. Calculate this age in years. [3]
4. (d) Describe how astronomers can find the distance to a far galaxy without using its speed. [1]

Galaxy A is 3.0 × 10²⁴ m from the Earth and galaxy B is 1.2 × 10²⁵ m from the Earth.

1. (a) Calculate the speed at which each galaxy is moving away from the Earth. H₀ = 2.2 × 10⁻¹⁸ per second. [2]
2. (b) State which galaxy shows the greater redshift. Explain your answer. [2]
3. (c) A student says: 'All galaxies are moving away from the Earth, so the Earth must be at the centre of the Universe.' Explain why this conclusion is not correct. [2]

1. (a) Describe what happens in the core of a very massive star near the end of its life, leading to a supernova. [2]
2. (b) Explain why scientists say 'the iron in your blood was made inside stars'. [2]
3. (c) Explain why the Sun will not become a supernova. [1]
4. (d) State why a black hole cannot be seen directly. [1]

In the 1960s, radio engineers found a faint signal that their antenna picked up whichever direction it pointed.

1. (a) State what is meant by the cosmic microwave background radiation (CMBR). [2]
2. (b) Explain how the CMBR was produced and why it is now detected as microwaves. [3]
3. (c) Explain how the CMBR supports the Big Bang theory. [1]

1. (a) Approximately how long does the Earth take to orbit the Sun once?A 24 hoursB about one monthC about 365 daysD about 12 years [1]

1. (a) What is the main cause of the seasons on Earth?A The distance between the Earth and the Sun changes a lot during the year.B The Earth's axis is tilted relative to the plane of its orbit.C The Moon blocks some sunlight during winter.D The Sun gives out more energy in summer. [1]

1. (a) Explain why there is day and night in Lahore. [2]
2. (b) Explain why the Sun appears to rise in the east and set in the west. [2]
3. (c) In June the Sun is higher in the sky at midday in Lahore than in December. Explain why. [2]

The start of the Islamic month is decided by sighting the thin crescent Moon after the new moon.

1. (a) State approximately how long the Moon takes to orbit the Earth. [1]
2. (b) Explain why the Moon can be seen even though it does not give out its own light. [1]
3. (c) Explain why the Moon appears to change shape (phases) during a month. [2]

A science club in Sialkot is making a display about the Solar System.

1. (a) Name the star at the centre of the Solar System. [1]
2. (b) State how many planets there are in the Solar System and name the two closest to the Sun. [2]
3. (c) Pluto was once called the ninth planet. State how it is now classified. [1]
4. (d) Name two other types of object, apart from planets and dwarf planets, that orbit the Sun or a planet. [2]

1. (a) Which planet is the fifth planet from the Sun and the largest in the Solar System?A SaturnB MarsC JupiterD Neptune [1]

The Earth moves around the Sun in an almost circular orbit of radius 1.5 × 10¹¹ m. One orbit takes 365 days.

1. (a) Write down the equation for the average orbital speed of an object in a circular orbit, defining each symbol. [1]
2. (b) Calculate the average orbital speed of the Earth in m/s. [3]
3. (c) State the force that keeps the Earth in its orbit and the body that provides it. [1]

The Moon orbits the Earth at an average distance of 3.84 × 10⁸ m with an orbital period of 27.3 days.

1. (a) Calculate the average orbital speed of the Moon. Give your answer in km/s to 3 significant figures. [3]
2. (b) A student forgets to convert days to seconds. State the value of the speed she obtains and explain why it is not in m/s. [2]
3. (c) State why the same side of the Moon always faces the Earth. [1]

Data for five planets:planet: Mercury, Venus, Earth, Mars, Jupiterdistance from Sun / million km: 58, 108, 150, 228, 778orbital period / Earth years: 0.24, 0.62, 1.00, 1.88, 11.9mean surface temperature / °C: 167, 464, 15, −65, −110 (cloud tops)mean density / g/cm³: 5.4, 5.2, 5.5, 3.9, 1.3

1. (a) Describe the relationship between distance from the Sun and orbital period. [1]
2. (b) Use the data to suggest why the inner four planets are rocky and Jupiter is a gas giant. Refer to how the Solar System formed. [3]
3. (c) Venus is further from the Sun than Mercury but is hotter. Explain why. [2]

The average distance from the Sun to the Earth is 1.5 × 10¹¹ m and from the Sun to Jupiter is 7.78 × 10¹¹ m. The speed of light is 3.0 × 10⁸ m/s.

1. (a) Calculate the time taken for light to travel from the Sun to the Earth. [2]
2. (b) Calculate the time for light to travel from the Sun to Jupiter, in minutes. [2]
3. (c) Describe how the strength of the Sun's gravitational field changes from the Earth's orbit to Jupiter's orbit, and state its effect on the orbital speed of the planets. [2]

A comet orbits the Sun in a very elongated (elliptical) orbit. At its closest it passes inside the orbit of Venus; at its furthest it is beyond Neptune.

1. (a) State where in its orbit the comet moves fastest. [1]
2. (b) Explain, in terms of energy, why the comet's speed changes around its orbit. [3]
3. (c) Explain why the gravitational force on the comet is greatest when it is nearest the Sun. [1]
4. (d) Suggest why the comet develops a bright tail only when it is close to the Sun. [1]

Io is a moon of Jupiter. It orbits at a radius of 4.22 × 10⁸ m with a period of 1.77 days.

1. (a) Calculate the average orbital speed of Io in m/s. [3]
2. (b) The Moon orbits the Earth at a similar radius of 3.84 × 10⁸ m with a speed of about 1.0 × 10³ m/s. Calculate how many times faster Io moves. [1]
3. (c) Explain why Io moves much faster than the Moon even though their orbital radii are similar. [2]

1. (a) Describe how the Solar System formed according to the accretion model. [3]
2. (b) Explain why the Sun contains more than 99 % of the mass of the Solar System. [1]
3. (c) Explain why all the planets orbit the Sun in the same direction and in nearly the same plane. [2]

A robotic rover of mass 950 kg is sent to Mars.

1. (a) Calculate the weight of the rover on Earth and on Mars. Gravitational field strength: Earth 9.8 N/kg; Mars 3.7 N/kg. [2]
2. (b) Suggest why the gravitational field strength at the surface of Mars is less than at the surface of the Earth. [1]
3. (c) Mars orbits the Sun at a radius of 2.28 × 10¹¹ m with a period of 687 Earth days. Calculate its orbital speed in km/s. [3]
4. (d) The Earth's orbital speed is about 30 km/s. Explain why Mars moves more slowly. [1]