Which of the following facts about Pluto is false?

The assertion that Pluto was discovered by Voyager 2 in 1989 is incorrect. Pluto was actually discovered in 1930 by Clyde Tombaugh at the Lowell Observatory in Arizona. Voyager 2, a spacecraft launched by NASA, flew by Uranus and Neptune in 1986 and 1989, respectively, but it did not encounter or discover Pluto, which is much farther from the Sun and was not visited by a spacecraft until New Horizons flew by in 2015.

Understanding the other facts about Pluto supports recognizing how the inaccuracies arise. For instance, the classification of Pluto as part of a binary planetary system is indeed accurate due to its relationship with its largest moon, Charon, which is comparable in size, creating a center of mass outside of Pluto. Additionally, Pluto's unique orbit, which brings it inside the orbit of Neptune for 20 years during its 248-year cycle, is a fascinating aspect of its dynamics. Lastly, scientific measurements of Pluto's mass and density have indicated it is primarily composed of rock and methane ice, which aligns with current understanding of its composition.