Circumstellar disks are flat, rotating disks of gas and dust that surround young stars. These disks are thought to be the remnants of the material from which the star formed, and they play a crucial role in the formation of planets. By studying circumstellar disks, astronomers can learn more about the processes of planet formation and the early stages of a star's life. Observations of circumstellar disks are often done using telescopes and techniques that allow researchers to study the composition, structure, and dynamics of the disk.