HUBBLE FIGURES OUT HALO AROUND ANDROMEDA GALAXY.
HUBBLE FIGURES OUT HALO AROUND ANDROMEDA GALAXY In a landmark study, scientists using NASA’s Hubble Space Telescope have figured out the immense envelope of gas, called a halo, surrounding the Andromeda galaxy, our nearest large galactic neighbor. Scientists were surprised to find nearly invisible halo of diffuse plasma extends 1.3 million light-years from the galaxy—about halfway to our Milky Way—and as far as 2 million light-years in some directions. This means that Andromeda’s halo is already bumping into the halo of our own galaxy. They also found that the halo has a layered structure, with two main nested and distinct shells of gas. This is the most comprehensive study of a halo surrounding a galaxy. The Andromeda galaxy, also known as M31 , is a majestic spiral of perhaps as many as 1 trillion stars and comparable in size to our Milky Way. At a distance of 2.5 million light-years, it is so close to us that the galaxy appears as a cigar-shaped smudge of light high in the autumn