Free Astronomy Magazine September-October 2022

47 SEPTEMBER-OCTOBER 2022 ASTRO PUBLISHING T he Large Magellanic Cloud (LMC) is a satellite of the Milky Way, containing about 30 billion stars. Seen here in a far-infrared and radio view, the LMC’s cool and warm dust are shown in green and blue, respectively, with hydrogen gas in 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 re- tired NASA missions: the Infrared Astronomy Survey and Cosmic Background Ex- plorer, as well as the Parkes, ATCA, and Mopra radio telescopes. [ESA, NASA, NASA- JPL, Caltech, Christopher Clark (STScI), S. Kim (Sejong University), T. Wong (UIUC)] T he 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 mis- sion, 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. [ESA, NASA, NASA-JPL, Caltech, Christopher Clark (STScI), R. Braun (SKA Obs.), C. Nieten (MPI Radioastronomie), Matt Smith (Cardiff Univ.)] Many of the heavy chemical ele- ments essential to forming planets like Earth are locked up in dust grains in interstellar space. Under- standing dust is an essential part of understanding our universe. The observations were made possi- ble through the work of ESA’s Her- schel Space Observatory, which operated from 2009 to 2013. Her- schel’s super-cold instruments were able to detect the thermal glow of dust, which is emitted as far-infrared light, a range of wavelengths longer than what human eyes can detect. Herschel’s images of interstellar dust provide high-resolution views of fine details in these clouds, revealing intricate substructures. But the way the space telescope was designed meant that it often couldn’t detect light from clouds that are more