P1 Specification

Module P1: The Earth and the Universe

P1.1 What do we know about the place of the Earth in the Universe?

1. recall that the Earth is one of eight planets moving in almost circular paths round the Sun

which, together with other smaller objects orbiting the Sun (asteroids, dwarf planets, comets)

and moons orbiting several planets, make up the solar system

2. describe the principal differences between planets, moons, the Sun, comets and asteroids

including their relative sizes and motions

3. understand that the solar system was formed over very long periods from clouds of gases and

dust in space, about five thousand million years ago

4. recall that the Sun is one of thousands of millions of stars in the Milky Way galaxy

5. recall that there are thousands of millions of galaxies, each containing thousands of millions of

stars, and that all of these galaxies make up the Universe

6. put in order and recall the relative sizes of: the diameters of the Earth, the Sun, the Earth’s

orbit, the solar system, the Milky Way, the distance from the Sun to the nearest star, and the

distance from the Milky Way to the nearest galaxy

7. understand that all the evidence we have about distant stars and galaxies comes from the

radiation astronomers can detect

8. recall that light travels through space (a vacuum) at a very high but  finite speed, 300 000 km/s

9. recall that a light-year is the distance travelled by light in a year

10. understand that the [1] nite speed of light means that very distant objects are observed as they

were in the past, when the light we now see left them

11. understand how the distance to a star can be measured using parallax (qualitative idea only)

12. understand how the distance to a star can be estimated from its relative brightness

13. understand that light pollution and other atmospheric conditions interfere with observations of

the night sky

14. explain why there are uncertainties about the distances of stars and galaxies with reference

to the nature and difficulty of the observations on which these are based and the assumptions

made in interpreting them

15. understand that the source of the Sun’s energy is the fusion of hydrogen nuclei

16. understand that all chemical elements with atoms heavier than helium were made in stars

17. understand that the redshift in the light coming from them suggests that distant galaxies

are moving away from us

18. understand that (in general) the further away a galaxy is, the faster it is moving away

from us

19. understand how the motions of galaxies suggests that space itself is expanding

20. recall and put in order the relative ages of the Earth, the Sun, and the Universe

21. recall that scientists believe the Universe began with a ‘big bang’ about 14 thousand million

years ago

22. understand that the ultimate fate of the Universe is dif[1] cult to predict because of difficulties in

measuring the very large distances involved and the mass of the Universe, and studying the

motion of very distant objects.

P1.2 What do we know about the Earth and how it is changing?

1. understand how rocks provide evidence for changes in the Earth (erosion and sedimentation,

fossils, folding)

2. understand that continents would be worn down to sea level by erosion, if mountains were not

being continuously formed

3. understand that the rock processes seen today can account for past changes

4. understand that the age of the Earth can be estimated from, and must be greater than, the

age of its oldest rocks, which are about four thousand million years old

5. understand Wegener’s theory of continental drift and his evidence for it (geometric [1] t of

continents and their matching fossils and rock layers)

6. understand how Wegener’s theory accounts for mountain building

7. understand reasons for the rejection of Wegener’s theory by geologists of his time (movement

of continents not detectable, too big an idea from limited evidence, simpler explanations of the

same evidence, Wegener an outsider to the community of geologists)

8. understand that sea floor spreading is a consequence of movement of the mantle (convection

due to heating by the core)

9. recall that sea floors spread by a few centimetres a year

10. understand how sea floor spreading and the periodic reversals of the Earth’s magnetic field can explain the pattern in the magnetisation of sea floor rocks on either side of the

oceanic ridges

11. understand that earthquakes, volcanoes and mountain building generally occur at the edges

of tectonic plates

12. understand how the movement of tectonic plates causes earthquakes, volcanoes and

mountain building, and contributes to the rock cycle

13. recall that earthquakes produce wave motions on the surface and inside the Earth which can

be detected by instruments located on the Earth’s surface

14. recall that earthquakes produce:

a. P-waves (longitudinal waves) which travel through solids and liquids

b. S-waves (transverse waves) which travel through solids but not liquids

15. describe the difference between a transverse and longitudinal wave

16. understand how differences in the wave speeds and behaviour of P-waves and S-waves can

be used to give evidence for the structure of the Earth

17. in relation to waves, use the equation:

distance = wave speed × time

(metres, m) (metres per second, m/s) (seconds, s)

18. draw and label a diagram of the Earth to show its crust, mantle and core

19. recall that a wave is a disturbance, caused by a vibrating source, that transfers energy in the

direction that the wave travels, without transferring matter

20. recall that the frequency of waves, in hertz (Hz), is the number of waves each second that are

made by the source, or that pass through any particular point

21. recall that the wavelength of waves is the distance between the corresponding points on two

adjacent cycles

22. recall that the amplitude of a wave is the distance from the maximum displacement to the

undisturbed position

23. draw and interpret diagrams showing the amplitude and the wavelength of waves

24. use the equation:

wave speed = frequency × wavelength

(metres per second, m/s) (hertz, Hz) (metres, m)

25. understand that for a constant wave speed the wavelength of the wave is inversely

proportional to the frequency.

© OCR 2011 GCSE Science A