Cepheids, also called Cepheid Variables, are stars which brigthen and dim periodically. This behavior allows them to be used as cosmic yardsticks out to distances of a few tens of millions of light-years. a uniform function of their brightness. The reason Cepheids can be used to determine distance is because the are variable stars that change brightness according to a regular pattern Cepheid variable discovery allows one to know the true luminosity of a Cepheid by simply observing its pulsation period. This in turn allows one to determine the distance to the star, by comparing its known luminosity to its observed brightness.
The law must last several levels of approval and if it contradicts or conflicts with a federal law the law literally can not go in place do to the fact that federal laws are more for everyone than just for the people of a certain area