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In general, astronomers seek an understanding of how the Universe works; from the planets in our own Solar System, to the evolution of stars and nebulae, to whole systems of galaxies, to the properties and fate of the Universe as a whole. Modern astronomy is an interdisciplinary science that relies upon, and furthers the development of, fields such as physics, chemistry, computer science, and mathematics.
Only the very nearest astronomical objects (all within our Solar System) can be reached by spacecraft in a reasonable amount of time. Information about all other objects comes indirectly from earth-bound telescopes or earth-orbiting satellites, which observe light emitted or reflected from such objects. The collection and detailed analysis of this light is key to unlocking the mysteries of the observable Universe. The sole purpose of a telescope is to collect this light; it is the role of the astronomer to analyze and interpret this data.