10 Amazing Facts About Pluto You Need to Know
On February 18, 1930, Tombaugh discovered the tiny, distant object by use of a new astronomic technique of photographic plates combined with a blink microscope. His finding was confirmed by several other astronomers, and on March 13, 1930 the discovery of Pluto was publicly announced.
2. Pluto is in a region called the Kuiper Belt
The Kuiper Belt contains thousands of small, icy objects. Pluto was the first true Kuiper Belt Object to be seen. Other objects soon followed, and astronomers quickly saw that the region beyond Neptune teemed with icy rocks and tiny worlds.
New Horizons launched on Jan. 19, 2006 and completed a nine-year, 3-billion mile journey to conducted a six-month-long reconnaissance flyby study of Pluto and its moons in summer 2015, culminating with Pluto closest approach on July 14, 2015. As part of an extended mission, the spacecraft is expected to head farther into the Kuiper Belt to examine another of the ancient, icy mini-worlds in that vast region.
New Horizons‘ latest views of Pluto have shown the dwarf planet to be 1,473 miles (2,370 kilometers) across, making it the largest body in the icy Kuiper Belt at the edge of the solar system. While Earth’s moon has a diameter of 2,160 miles. Pluto is 18.5% the size of Earth.
5. Pluto has five known moons
Pluto has five moons down to a detection limit of about 1 km in diameter. In order of distance from Pluto they are Charon, Styx, Nix, Kerberos, and Hydra.
Charon, the largest of the five moons, is mutually tidally locked with Pluto, and is massive enough that Pluto–Charon is sometimes considered a double dwarf planet. The same surfaces of Charon and Pluto always face each other, a phenomenon called mutual tidal locking. Charon orbits Pluto every 6.4 Earth days.
7. Pluto was demoted to a dwarf planet in 2006
In August 2006 the International Astronomical Union (IAU) downgraded the status of Pluto to that of “dwarf planet.” A dwarf planet is a celestial body in direct orbit of the Sun that is massive enough that its shape is controlled by gravitational forces rather than mechanical forces but has not cleared its neighboring region of other objects. Pluto meets only two of these criteria, losing out on the third. In all the billions of years since its formation, Pluto has not managed to clear its neighborhood.
The New Horizons spacecraft confirmed that Pluto does indeed have an atmosphere. It’s thin and almost entirely of nitrogen (N2), with minor amounts of methane (CH4) and carbon monoxide (CO), all of which are vaporized from their ices on Pluto’s surface.
9. Pluto and Neptune cross orbits
Neptune has a circular orbit; however, Pluto’s has a highly eccentric orbit, varying its distance to the Sun a tremendous amount. Because of this, Pluto can actually get closer to the Sun than Neptune. The last time this happened was in 1979 until 1999 and won’t happen again until 2207. During that period, Neptune was actually the most distant planet from the Sun, and Pluto was actually closer. Neptune’s huge mass can not eject Pluto from orbit because they have orbital resonance, meaning they’re never in the same region of space at the same time.
New close-up images from the New Horizons spacecraft reveal a giant surprise: a range of youthful mountains rising as high as 11,000 feet (3,500 meters) above the surface of the icy body. The mountains likely formed no more than 100 million years ago, may still be in the process of building. That suggests that Pluto’s surface may still be geologically active today.