Complex sentence: Interpretation of this fact would lead one to believe that the Earth's position is fixed on the lunar sky and no earthrises can occur, however, the Moon librates slightly, which causes the Earth to draw a Lissajous figure on the sky.
Split into simpler sentences: Interpretation of this fact would lead one to believe that the Earth's position is fixed on the lunar sky and no earthrises can occur. However, the Moon librates slightly, which causes the Earth to draw a Lissajous figure on the sky.