We saw in this chapter how the use of relation of `` standardization '' made it possible to use the supernovæ of the Ia type like standard candle to make estimates of distance allowing measurements of cosmology.
We then detailed the various sources of systematic effects being able to bias these measurements. They seem that the majority of these errors are under control. However, we saw that certain models like the models of gray dust are always in agreement with the observations. A study of supernovæ with great redshift would make it possible to test in a final way this kind of model.