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Origins of the universe Summary questions a) Electromagnetic waves emitted by a source moving: away from us are ______________ in wavelength. towards us are ______________ in wavelength. The change of wavelength increases with the ______________ of the source. b) i) The increase in wavelength of light from a star or galaxy moving away from us is called a _____________________. ii) Light from all the distant galaxies is red-shifted to ______________ wavelengths. iii) The red-shift of a distant galaxy ______________ with distance from us. a) i) The further away a distant galaxy is, the ______________ the speed at which it is moving away from us. ii) All the distant galaxies are moving ______________ from each other. b) i) The Universe must be ______________ because all the distant galaxies are moving away from each other. ii) The most distant galaxies are about ______________ million light years away. a) The Universe started with the ______________, a massive explosion from a very small point. b) Background microwave radiation is radiation created just after the ______________. c) If the average ______________ of the Universe is: i) less than a certain amount, it will ____________________________. The stars will die out. ii) more than a certain amount, it will stop expanding and ___________________________. Everything will head for a Big ______________. 4 a) The Earth’s atmosphere ______________ all electromagnetic waves except visible light, radio waves and some ultraviolet radiation. b) Satellite detectors are used to make observations outside the ______________ and the ______________ parts of the electromagnetic spectrum. QUESTION FIVE The drawing shows a satellite which carries a telescope used to observe space. Match words, A, B, C and D, with the numbers 1– 4 in the sentences. A B C D a distant galaxy______ a satellite_____ the Earth_____ the Universe_____ Observations of space using visible light are better from . . . 1 . . . because clouds may block observations taken from . . . 2 . . . .The red-shift in light from . . . 3 . . . provides evidence of the ‘big bang’ theory of the start of . . . 4 . . . . QUESTION EIGHT Light from every star, in every distant galaxy which has been observed, shows a red-shift. 8A Why has the feature been given this name? 1 2 3 4 Blue light has a longer wavelength than red light. Red light has a higher frequency than blue light. Red light travels at a higher speed than blue light. Red light has a longer wavelength than blue light. 8B Which row in the table correctly describes the movement of galaxies at the present time? 8C Scientists have used their calculations to deduce the movement of galaxies hundreds of millions of years ago. Which row in the table correctly describes the movement of galaxies hundreds of millions of years ago? 8D Red-shift provides direct evidence that the Universe . . . 1 2 3 4 is expanding. is expanding and must have started at the ‘big bang’. is expanding and must have started from a tiny starting point. is expanding and must have started from a tiny starting point at the ‘big bang’. QUESTION NINE The astronomer Hubble calculated the distance of many galaxies from Earth. He also calculated the velocity at which many galaxies are moving away from Earth.The graph shows some of his results. The distance is given in megaparsecs. One parsec is approximately equal to 30 000 000 000km. 9A The data in the graph suggests that . . . 1 the further away the galaxy is from Earth, the slower it is moving. all galaxies move at different velocities. the velocity of a galaxy is proportional to its distance away from Earth. there is no relationship between the speed of a galaxy and its distance away from Earth. 2 3 4 9B The gradient of the line of best fit on the graph is known as the Hubble constant. The Hubble constant can be used to estimate the age of the Universe. From this data, the approximate value of the Hubble constant in km/s per megaparsec is . . . 1 2 3 4 4. 500. 1000. 2000. 9C Modern astronomers calculate that the actual value of the Hubble constant is somewhere between 46 and 80km/s per megaparsec. This is very different from the number calculated from the graph. This is because Hubble’s measurements had . . . 1 2 3 4 random errors. systematic errors. zero errors. lack of precision. 9D The Andromeda galaxy is moving towards our own Milky Way galaxy. This means that, as viewed from Earth, light from the Andromeda galaxy will . . . 1 2 3 4 be shifted towards the red end of the spectrum. show an increase in wavelengths. be shifted towards the blue end of the spectrum. show a decrease in frequencies.