A team of scientists used the Hubble Space Telescope to measure the extent of the halo of the gas surrounds the Andromeda galaxy. It turned out to be much larger than expected stretching for about a million light-years from the galaxy. This means it reaches out to about half the distance that separates it from the Milky Way so if it was visible to the naked eye its size would be about a hundred times that of the full Moon. The results of this research were published in “Astrophysical Journal”.