GCSE Astronomy Topic 16 Practice Questions

A change in wavelength due to relative motion between observer and source - ANSWERSWhat is the Doppler Principle? A longer wavelength - ANSWERSIf an object is moving away what is its wavelength? Using the shift of the absorption lines - ANSWERSHow can we calculate the radial velocity? The object is moving faster - ANSWERSOn the visible spectrum if the lines move more what does that mean? v= Ho d - ANSWERSWhat is hubbles law? 68 km/s/Mpc - ANSWERSWhat is hubbles constant? The distance of a galaxy and their radial velocity - ANSWERSWhat does hubbles law link to? Convert Mpc to km Divide 1/Ans Convert seconds to years - ANSWERSHow would you work out the age of the universe from hubbles constant? The whole universe was in a very small, hot, dense state and it began to expand - ANSWERSWhat is the Big Bang Theory? That the density of the universe decreases over time as it expands - ANSWERSWhat does the Big Bang model mean about density? They only have high redshifts implying they are far away and therefore created when the universe was young - ANSWERSWhat evidence in Quasars is there for Big Bang? Universe will have cooled as it expands and its temperature was to be estimated just above 0K - ANSWERSWhat evidence in Cosmic Microwave Background is there for Big Bang? A very long exposure image of a small part of "blank" sky which revealed thousands of distant and old galaxies - ANSWERSWhat evidence in Hubble Deep Field Image is there for Big Bang? Universe has and always is expanding but density stays the same meaning new matter must constantly be created - ANSWERSWhat is the Steady State Theory? Part of the cyclic universe idea meaning it expands then collapses and repeats - ANSWERSWhat is the "Big Crunch"? Universe will expand at a slower and slower rate until not expanding anymore - ANSWERSWhat is Slow Expansion? Universe will continue to expand at a constant rate - ANSWERSWhat is Expands Forever? Universe expansion rate will increase, expanding more and more quickly which is what we observe - ANSWERSWhat is Accelerating Expansion? More gravity than there should be for mass we can see - ANSWERSWhat is the problem with matter? Invisible mass known as dark matter which makes up around 25% of all matter - ANSWERSWhat is the solution to matter? Universe is expanding at a faster and faster rate - ANSWERSWhat is the problem with energy? Invisible energy known as dark energy which powers the expansion - ANSWERSWhat is the solution to energy? 300,000 km/s - ANSWERSWhat is the speed of light? speed of light X Hubble Time - ANSWERSWhat is the formula for Hubble Length? 4.6x10^17 s - ANSWERSWhat is the Hubble Time? 14 billion years - ANSWERSWhat does Hubble Time correspond to? The apparent 'bending' of light from galaxies to form multiple images of the same galaxy - ANSWERSHow does dark matter explain gravitational lensing?