Why do you suppose the tilt of Uranus's rotation axis was deduced from the orbits of its satellites and not by observing the rotation of the planet itself?

Planetary rotations refer to the spinning of planets around their axes, just like the Earth takes approximately 24 hours to complete a full rotation, thus creating day and night. However, unlike Earth, not all planets rotate with the same orientation or speed. Some planets, like Uranus, have unique rotational characteristics that puzzle astronomers.

For instance, Uranus's rotation axis is tilted at about 98 degrees, almost lying on its orbital plane - unlike Earth which is tilted at about 23.5 degrees. This extreme tilt affects the way Uranus experiences seasons and has a direct impact on the dynamics of the planet's atmosphere and weather patterns. It’s fascinating to note how this axial tilt also affects the orbits of Uranus’s moons, giving us visible clues to piece together the planet's rotation without directly observing the surface.

The orbits of satellites provide significant insight into the characteristics of a planet's rotation. A satellite, often a moon, travels in a path that coincides with the equatorial plane of its planet. Therefore, by studying the motion of these satellites, astronomers can determine essential aspects of a planet’s rotation such as the tilt of its axis and the direction of rotation.

In the unique scenario of Uranus, its moons orbit in an almost perpendicular manner compared to other planets, mirroring the planet's unusual axial tilt. By analyzing these orbits, scientists were able to infer that Uranus has an extreme axial tilt without having to depend on visual cues from the planetary surface, which are hard to capture due to the planet's distant location and its dense atmosphere obscuring detailed visual observation.

Observational astronomy is the art and science of examining celestial objects to understand the universe's many mysteries. Through telescopes and other instruments, astronomers observe planets, stars, galaxies, and other astronomical bodies to study their motions, compositions, and other properties. With innovative technologies, astronomers today can observe objects that are billions of light-years away.

Uranus presents a fascinating challenge for observational astronomy due to its extreme tilt and distant location. The planet's orientation leads to unusual seasonal changes and affects the visibility of its rotation. Observational astronomy, therefore, relies on indirect methods, such as studying satellite orbits, to deduce characteristics like the axial tilt of planets when direct visual observation is not feasible. The extraordinary rotation of Uranus, while not observable in the direct manner seen with other planets, is an exemplar of how astronomers can piece together the puzzle of our solar system using a variety of observational techniques.