Itʹs a dusty Universe: surface science in space

We live in a dusty Universe! Dust is not only found in our solar system among the planets but is found in a wide variety of objects throughout the Universe, mainly in those regions between the stars known as interstellar clouds. Interstellar dust particles, which consist of cores of silicates and carbonaceous material often surrounded by icy mantles, are most probably highly irregular in shape with a size distribution from micro- to nanometers. Interstellar dust is important for many reasons, including the template it provides for surface chemical reactions that form, among other species, the most important interstellar molecule––H2. In this article, we discuss the evidence for interstellar dust, its physical and chemical properties, its role in interstellar surface chemistry, and what remains to be learned.