Spectroscopy. The diagram shows what a spectrum is and how it may contain absorption lines. These lines can be matched up with those of substances known from laboratory tests. Annie Cannon once said that astronomical spectroscopy made it "almost as if the distant stars had acquired speech."
A beautiful new image of two colliding galaxies has been released by NASA's Great Observatories. The Antennae galaxies, located about 62 million light-years from Earth, are shown in this composite image from the Chandra X-ray Observatory (blue), the Hubble Space Telescope (gold and brown), and the Spitzer Space Telescope (red).
Central area of the Milky Way galaxy, released by astronomers at the European Southern Observatory's Paranal Observatory in Chile. The photo shows 84 million stars in an image measuring 108,500×81,500, which contains nearly 9 billion pixels, and is actually a composite of thousands of individual photographs shot with the observatory's VISTA survey telescope.