Pluto.
Orbit and rotation. Geology and geography. Mass and size. Atmosphere of Pluto. Moons of Pluto. Origin. Observation and exploration. Pluto. Pluto's History & Naming Pluto is the only dwarf planet to once have been considered a major planet.
Once thought of as the ninth planet and the one most distant from the sun, Pluto is now seen as one of the largest known members of the Kuiper Belt, a shadowy disk-like zone beyond the orbit of Neptune populated by a trillion or more comets. Pluto was reclassified as a dwarf planet in 2006, a change widely thought of as a demotion that has attracted controversy and debate. American astronomer Percival Lowell first caught hints of Pluto's existence in 1905 from odd deviations he observed in the orbits of Neptune and Uranus, suggesting that another world's gravity was tugging at them from beyond.
He predicted its location in 1915, but died without finding it. Scientists Discover that Something Enormous is Hiding Behind Pluto (Literally) Image of Pluto taken by New Horizons.
Image Credit: NASA Just a week ago, New Horizons made its historic flyby of Pluto and its five small moons (Charon, Styx, Nix, Kerberos, and Hydra). The pictures that the spacecraft returned so far are simply staggering (because the craft is so far away, it will take more than a year to receive all of the data). But already, we see that Charon is round and pockmarked. We see that pluto has a heart splashed across its surface. A tail! Saturn may have a glorious ring system, but Pluto has its own claim to fame: A plasma tail.
Since the discovery is so recent, it is currently unknown exactly how large this tail is or what form its structure takes; however, further analysis of the data should allow scientists to uncover more information. Tyson vs Colbert in an Epic Fight for Pluto. There are a lot of people who are mad that Pluto is a dwarf planet.
People like Stephen Colbert. The small, icy world was downgraded by the International Astronomical Union back in 2006, and many people (like Stephen Colbert) blame astrophysicist Neil deGrasse Tyson for the demotion. Indeed, many assert that Tyson single handedly championed Pluto’s downfall. In an interview this week, Colbert tried his hardest to get Tyson to change his mind and admit that Pluto should, once again, be a planet. Ultimately, Colbert’s argument centered on the recently obtained images of the dwarf planet, which come thanks to NASA’s New Horizons mission.
Image from the Long Range Reconnaissance Imager (LORRI) aboard New Horizons, taken on July 13, 2015 To defend his position, Colbert asserted, “It looks like a planet, it’s got atmosphere, it even has a heart—unlike you.” The journey to Pluto took us nearly a decade, and that’s just counting travel time. The Late Show Video - 9th Rock from the Sun - CBS.com.