## Overview This topic studies the continuous emission and line absorption spectra of the Sun. It uses Wien’s displacement law, Stefan’s law, and the inverse square law to also investigate properties of stars, such as luminosity, size, temperature and distance. ## Mathematical Skills There are a number of opportunities for the development of mathematical skills in this unit. These include recognising and using expressions in decimal and standard form; estimating results; making order of magnitude calculations; solving algebraic equations, including quadratic equations; calculating surface areas of spheres. ## How Science Works There are opportunities within this topic for learners to use knowledge and understanding to pose scientific questions, define scientific problems, present scientific arguments and scientific ideas; to analyse and interpret data to provide evidence, recognise correlations and causal relationships; to know that scientific knowledge and understanding develops over time. ### Learners should be able to demonstrate and apply their knowledge and understanding of: (a) the idea that the stellar spectrum consists of a continuous emission spectrum, from the dense gas of the surface of the star, and a line absorption spectrum arising from the passage of the emitted electromagnetic radiation through the tenuous atmosphere of the star (b) the idea that bodies which absorb all incident radiation are known as black bodies and that stars are very good approximations to black bodies (c) the shape of the black body spectrum and that the peak wavelength is inversely proportional to the absolute temperature (defined by: T (K) =  ( oC) + 273.15) (d) Wien's displacement law, Stefan's law and the inverse square law to investigate the properties of stars – luminosity, size, temperature and distance (N.B. stellar brightness in magnitudes will not be required) (e) the meaning of multiwavelength astronomy and that by studying a region of space at different wavelengths (different photon energies) the different processes which took place there can be revealed