A Mira variable is a type of pulsating star that experiences significant changes in brightness over time. These stars are typically red giants, and their brightness can vary by several magnitudes, often taking about 80 to 100 days to complete one cycle. The changes in brightness are caused by the expansion and contraction of the star's outer layers. The name "Mira" comes from the first discovered star of this type, Mira Ceti, which is located in the constellation Cetus. Mira variables are important for astronomers because they help in understanding stellar evolution and the distance to galaxies through their predictable brightness variations.