In the pictures of the planetary nebulae, colour corresponds to temperature. Blue represents hotter regions of the nebulae and red, cooler. Scientists are probing these illuminated stellar relics in our neighboring galaxy because they are at relatively the same distance - about 168, 000 light-years -- from Earth. Knowing the distance to these objects allows scientists to compare their shapes and sizes, and precisely determine the brightness of their central stars. For this reason, even though these glowing remains of dying stars are about 50 times farther away than the stunning planetary nebulae photographed in the Milky Way, they are of invaluable importance.