can detect P1.1.8 recall that light travels through space (a vacuum) at a very high but finite speed, 300000km/s P1.1.3 Recall that all electromagnetic radiation is transmitted through space with the same very high (but finite) speed P1.1.9 recall that a light-year is the distance travelled by light in a year NA NA P1.1.1 understand that the finite speed of light means that very distant objects are observed as they were in the past, when the light we now see left them NA NA P1.1.1 understand how the distance to a star can be measured using parallax (qualitative idea only) NA NA P1.1.2 understand how the distance to a star can be estimated from its relative brightness NA NA P1.1.3 understand that light pollution and other atmospheric conditions interfere with observations of the night sky NA NA P1.1.4 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 NA NA P1.1.5 understand that the source of the Sun’s energy is the fusion of hydrogen nuclei P6.5.6 explain how the Sun was formed when collapsing cloud of dust and gas resulted in fusion reactions, leading to an equilibrium between gravitational collapse and expansion due to the fusion energy P1.1.6 understand that all chemical elements with atoms heavier than helium were made in stars NA NA P1.1.7 understand that the redshift in the light coming from them suggests that distant galaxies are moving away from us P6.5.7 explain the red-shift of light from galaxies which are receding qualitative only P1.1.8 understand that (in general) the further away a galaxy is, the faster it is moving away from us P6.5.8 explain that the relationship between the distance of each galaxy and its speed is evidence of an expanding universe model
P5.2.4 recall that the resistance of connecting wires is so small that it can usually be ignored P3.2.4 describe an experiment to investigate the resistance of a wire and be able to draw the circuit diagram of the circuit used P5.2.5 understand that when electric charge flows through a component (or device), work is done by the power supply, and energy is transferred from it to the component and/or its surroundings P3.4.1 describe the energy transfers that take place when a system is changed by work done when a current flows through a component P5.2.6 recall that power (in watts, W) is a measure of the rate at which an electrical power supply transfers energy to an appliance or device and/or its surroundings P3.4.2 explain, with reference to examples, how the power transfer in any circuit device is related to the energy transferred from the power supply to the device and its surroundings over a given time: power (W) = energy (J) ÷ time (s) P5.2.7 use the equation: power = voltage × current (watts, W) (volts, V) (amperes, A) P3.4.4 recall and apply the relationships between power transferred in any circuit device, the potential difference across it, the current through it, and its resistance: power (W) = potential difference (V) x current (A) power (W) = (current (A))2 x resistance (Ω) P5.2.8 recall that resistors get hotter when there is an electric current flowing through them, and understand that this heating effect is caused by collisions between the moving charges and ions in the wire NA NA P5.2.9 recall that this heating effect makes a lamp filament hot enough to glow P3.2.5 recall that for some components the value of R remains constant (fixed resistors) but that in others it can change as the current changes (e.g. heating elements, lamp filaments)
means that the star is further away P7.3.4 define a parsec (pc) as the distance to a star with a parallax angle of one second of arc NA NA P7.3.5 calculate distances in parsecs for simple parallax angles expressed as fractions of a second of arc NA NA P7.3.6 recall that a parsec is similar in magnitude to a light-year and is the unit used by astronomers to measure distance NA NA P7.3.7 recall that typical interstellar distances are a few parsecs NA NA P7.3.8 recall that the luminosity of a star depends on its temperature and its size NA NA P7.3.9 explain qualitatively why the observed intensity of light from a star (as seen on Earth) depends on the star’s luminosity and its distance from Earth NA NA P7.3.10 recall that Cepheid variable stars pulse in brightness, with a period related to their luminosity NA NA P7.3.11 recall that and explain qualitatively how this relationship enables astronomers to estimate the distance to Cepheid variable stars NA NA P7.3.12 understand the role of observations of Cepheid variable stars in establishing the scale of the Universe and the nature of most spiral nebulae as distant galaxies NA NA P7.3.13 recall that telescopes revealed that the Milky Way consists of millions of stars and led to the realisation that the Sun was a star in the Milky Way galaxy NA NA P7.3.14 recall that telescopes revealed the existence of many fuzzy objects in the night sky, and that these were originally called nebulae NA NA P7.3.15 recall the main issue in the debate: whether spiral nebulae were objects within the Milky Way or separate galaxies outside it NA NA
P7.4.27 recall that in a white dwarf star there is no nuclear fusion; the star gradually cools and fades NA NA P7.4.28 recall that in a high-mass star (several times the mass of the Sun) nuclear fusion can produce heavier nuclei up to and including iron; when the core is mostly iron, it explodes as a supernova creating nuclei with masses greater than iron and leaving a dense neutron star or a black hole. NA NA P7.4.29 understand that astronomers have found convincing evidence of planets around hundreds of nearby stars NA NA P7.4.30 understand that, if even a small proportion of stars have planets, many scientists think that it is likely that life exists elsewhere in the Universe NA NA P7.4.31 recall that no evidence of extraterrestrial life (at present or in the past) has so far been detected. NA NA P7.5.1 recall that major optical and infrared astronomical observatories on Earth are mostly situated in Chile, Hawaii, Australia and the Canary Islands NA NA P7.5.2 describe factors that influence the choice of site for major astronomical observatories including: a. high elevation b. frequent cloudless nights c. low atmospheric pollution and dry air d. sufficient distance from built up areas that cause light pollution NA NA P7.5.3 describe ways in which astronomers work with local or remote telescopes NA NA P7.5.4 explain the advantages of computer control of telescopes including: a. being able to work remotely b. continuous tracking of objects c. more precise positioning of the telescope d. computer recording and processing of data collected NA NA