The Small Magellanic Cloud is a satellite of the Milky Way, containing about 3 billion stars. This far-infrared and radio view of it shows the cool (green) and warm (blue) dust, as well as the hydrogen gas (red). The image is composed of data from the European Space Agency (ESA) Herschel mission, supplemented with data from ESA’s retired Planck observatory and two retired NASA missions: the Infrared Astronomy Survey and Cosmic Background Explorer, as well as the Parkes, ATCA, and NANTEN radio telescopes.

The Andromeda galaxy, or M31, is shown here in far-infrared and radio wavelengths of light. Some of the hydrogen gas (red) that traces the edge of Andromeda’s disc was pulled in from intergalactic space, and some was torn away from galaxies that merged with Andromeda far in the past. The image is composed of data from the European Space Agency (ESA) Herschel mission, supplemented with data from ESA’s retired Planck observatory and two retired NASA missions: the Infrared Astronomy Survey and Cosmic Background Explorer, as well as the Green Bank Telescope, WRST, and IRAM radio telescopes.

The Triangulum galaxy, or M33, is shown here in far-infrared and radio wavelengths of light. Some of the hydrogen gas (red) that traces the edge of the Triangulum’s disc was pulled in from intergalactic space, and some was torn away from galaxies that merged with Triangulum far in the past. The image is composed of data from the European Space Agency (ESA) Herschel mission, supplemented with data from ESA’s retired Planck observatory and two retired NASA missions: the Infrared Astronomy Survey and Cosmic Background Explorer, as well as the Very Large Array, Green Bank Telescope, and IRAM radio telescope.