Dust grains in the Material between the stars, consisting of gas, dust and cosmic rays (high energy charged particles moving at nearly the speed of light). It comprises ~10% of visible matter in the disk of our Galaxy (Milky Way). Until recently it was generally assumed that silicates in the ISM were amorphous, but Click on Term to Read More which act as nuclei (cores) around which other material can condense. The presence of dust was very important in causing matter to clump during the formation of the The Sun and set of objects orbiting around it including planets and their moons and rings, asteroids, comets, and meteoroids. by allowing radiation of heat.