Astrochemistry is the application of the science of chemistry to the universe and everything in it. Modern chemistry—the study of complex molecules and their interactions—has developed almost exclusively at or near Earth’s surface, with its temperature, gravity, and pressure conditions. Its application to the rest of the universe, then, is not quite as direct or ubiquitous as is the application of astrophysics. Even so, astrochemistry is extremely important to cosmic studies: The interactions of chemicals in planetary atmospheres and surfaces is vital to understanding the planets and other bodies in the solar system. Many chemicals have been detected in interstellar gas clouds throughout the Milky Way and other galaxies, including water, carbon monoxide, methane, ammonia, formaldehyde, acetone (which we use in nail polish remover), ethylene glycol (which we use in antifreeze), and even 1,3-dihydroxyacetone (which is found in sunless tanning lotion).