How do astronomers use science?
Astronomers must learn physics, chemistry, mathematics and computer science...and how to use a telescope, astronomers must rely on their observation skills, for instance physics has helped astronomers to understand what makes spiral galaxies have spiral shapes, another is Spectroscopy which is the use of light from a distant object to work out the object is made of, When something is moving away from you, it stretches that waveform, while if it moves towards you it…
A compound science is one that involves applying the knowledge and methods of one science in the pursuit of another. For instance, a geochemist might use their knowledge of chemistry to understand how rocks and minerals have formed. An astrophysicist might use physics to understand and explain observations made by astronomers.
This question appears to be related to what is called "outer space". With that in mind, the science of astronomy is the correct answer. With that said, however, it's important to know that astronomers often rely on the expertise of other scientists that work in the fields of physics, materials science and meteorology. These areas of expertise help astronomers in many aspects of their work including measurements.