Describe the key features of the light curve for a typical Type 1a supernova. In your answer, you should state the typical peak absolute magnitude, the overall shape of the curve (comparing the rate of rise to the rate of subsequent decay), and a suitable time scale in days over which the light curve is observed.

Define what is meant by a standard candle and explain how it is used to determine cosmological distances.

In the late 1990s, measurements of distant Type 1a supernovae led to a major breakthrough in cosmology. Describe these findings and explain the conclusions drawn from them regarding the expansion of the Universe.