Mira, << MY ruh, >> a giant red star, was one of the first stars of variable brightness to be discovered. In 1596, the German astronomer David Fabricius observed that the star changed over a period of months, dimming and then brightening. Because of this discovery, astronomers named the star mira after a Latin word meaning wonderful. At its brightest, Mira is about 100 times as bright as it is at its dimmest. Members of an amateur group, the American Association of Variable Observers, make observations of Mira and other variable stars.
Mira has about the same mass as the sun. But if its center were where the center of the sun is, Mira would extend beyond the orbit of Mars. Mira is roughly 400 light-years away from Earth.
In 2007, astronomers reported that Mira is ejecting material that forms a tail about 13 light-years long. The tail includes expelled hydrogen gas that is heated as Mira plows through the surrounding gas in the galaxy. The hydrogen gas gives off ultraviolet light, which enabled astronomers to discover the tail.
