Galaxies come in many shapes and sizes, from giant, slowly rotating ovals and fast-whirling spiral disks to faint ball-shaped blobs and dwarf irregulars. Most large, bright galaxies – including our own Milky Way – are orbited by a gang of much smaller dwarf galaxies.
Most of this we know from optical images, whether taken with small backyard telescopes or much bigger dedicated ground- and space-based telescopes that reveal the light from billions of distant suns. However, as we are discovering, what happens beyond the bright disk of stars may be even more interesting.
