Today, for the first and only time in the history of astronomy, a spacecraft encountered Uranus.
Puck was the first of 11 new moons discovered on Uranus by Voyager 2. Credit: NASA
Eight years after its launch, Voyager 2 made its closest approach to Uranus on January 24, 1986. The encounter and data-gathering was complicated due to Uranus’s 98-degree axial tilt and low light levels, but the spacecraft was able to pass about 50,600 miles (more than 81,400 kilometers) above the cloud tops. Several unique discoveries were made: Voyager detected an unusual magnetic field that was tilted about 55 degrees to the planet’s axis and offset from the planet’s center by one third of its radius. The probe also discovered 10 new moons (an 11th was found later in its data), adding to the five already known moons of Uranus, and two new rings, adding to the nine already known. Today, Voyager 2 remains the only spacecraft to have explored Uranus.
