Kepler's Harmonic Law:

Sets the Relative Scale of the Solar System. The Absolute Scale is still unknown and the most remote known planet is:

The Discovery of Uranus in 1781.

William Herschel

• Herschel also made detailed catalogs of the positions of the stars and chartered the change in position of double stars. From this data others showed that the positional changes of double stars could be understood from Kepler's Laws and Newtonian Mechanics if the two stars were in mutual orbit about one another Universality!

  The Discovery of Neptune in 1846 This stuff works to detect planets around nearby stars as well!

  Thomas Henderson and the first measurement of stellar parallax in 1839 This is a big deal because it now shows that the distance to the nearest stars is extremely large. This means that the stars are powered by an "unknown" source of energy.

  Well if the distance to the nearest stars was this large, how far away were the objects that Messier was finding: