# Uranus' axis of rotation-when discovered?

Who discovered it, and how was that accomplished. I had assumed it was known before Voyager 2 arrived at the planet since it isn't mentioned in JPL voyager 2 Uranus Approach

• The first two of Uranus' moons were discovered in 1787. en.wikipedia.org/wiki/… by William Hershal. Hershal was also the first to measure Mars' axial tilt (before Mars' 2 moons were discovered). If they assumed that Moons orbit the planets' equator, then suspicion of Uranus axis may have been as early as 1787, but that's just speculation on my part. – userLTK Jul 29 '19 at 3:18