An astronomer's observation is the study of celestial bodies in the SKY, such as stars, planets, comets, and other objects. Astronomers use telescopes and other instruments to observe these objects and record their findings. The term 'SKY' refers to the atmosphere and outer space, while a 'COMET' is a small, icy body that orbits the sun. By studying the SKY and comets, astronomers can gain insight into the formation and evolution of the universe.