Astronomy Picture of the Day

Explanation: Billions of stars light up the direction toward the centre of our Galaxy. The vast majority of these stars are themselves billions of years old, rivaling their home Milky Way Galaxy in raw age. These stars are much more faint and red than the occasional young blue stars that light up most galaxies. Together with interstellar dust, these old stars make a yellowish starscape, as pictured above. Although the opaque dust obscures the true Galactic centre in visible light, a relative hole in the dust occurs on the right of the image. This region, named Baade's Window for an astronomer who studied it, is used to inspect distant stars and to determine the internal geometry of the Milky Way. Baade's Window occurs toward the constellation of Sagittarius.