What two things do astronomers need to know about a star in order to calculate its luminosity or absolute magnitude? A. color and size B. color and distance C. distance and brightness D. size and distance

28. which is not a reason that water is used to store spent fuel rods from nuclear power plants? water increases the speed of the chain reaction in the fuel rods. water protects nuclear power plant workers from the high temperature and radiation of the fuel rods. water acts as a radiation shield to reduce the radiation levels. water cools the spent rods. salts action