Cosmic dust is a substance which is found throughout the Universe. It consists of small grains of material and aggregates of such grains, with a composition which can vary radically, depending on the circumstances in which the dust is formed. Cosmic dust often has a crystalline structure, and it has a number of interesting properties which attract the attention of astronomers and other researchers who work in space, including chemists, physicists, and theoretical mathematicians.

This substance was originally regarded as nothing more than a nuisance. Clouds of cosmic dust can obscure stars, planets, and other sights of interest in the Universe, and astronomers struggled for centuries to filter out cosmic dust so that they could make clear observations of various objects in the sky. Ultimately, researchers started to get interested in this extremely abundant substance, and they realized that cosmic dust actually plays a vital role in many of the processes in the Universe, including the formation of stars and planets.

There are a number of different types of cosmic dust. Circumplanetary dust, for example, orbits a planet in a distinctive ring shape; Saturn has quite a collection of circumplanetary dust. Interplanetary dust can be found within specific solar systems, scattered across asteroid belts and orbiting the system's star, for example. Interstellar dust spans the vast distances between the stars of a galaxy, sometimes concentrating into nebulae, while intergalactic dust can be found between galaxies.

Particles of cosmic dust vary widely in size. Most require magnification in order to be seen, with samples being collected from things like asteroids and meteors as well as specialized collectors on spacecraft for further study. Since cosmic dust is also the basic medium from which everything in the Universe is made, one could argue that technically things like your keyboard and even yourself are also made from cosmic dust, although most scientists prefer to study cosmic dust of extraterrestrial origin.

Studies of cosmic dust can reveal interesting information about how galaxies, individual stars, and planets form and ultimately destroy themselves. Some researchers have also realized that cosmic dust can actually be quite beautiful, as swirling images of nebulae have revealed. Observations of cosmic dust can be carried out with a variety of tools, ranging from simple telescopes to detectors which pick up on the radioactive emissions of cosmic dust.