Perfect - your background means I can speak a language you will understand.

The reason we know anything about the composition of stars, the distance to galaxies, their relative speed etc. is because we use a telescope and study spectral lines.

Your comparison of oceanography and boats is a poor analogy. The a analog to telescopes would be sonar (and maybe seismographs?). The analog to boats would be spaceships/rockets. This makes my point.