Transcript Pluto
Pluto A Dwarf Planet General Facts About Pluto Pluto orbits beyond the orbit of Neptune (usually) It is much smaller than any of the official planets and now classified as a "dwarf planet“ In Roman mythology, Pluto (Greek: Hades) is the god of the underworld Pluto was discovered in 1930 by a fortunate accident when American astronomer Clyde Tombaugh compared pictures of the sky over many nights. we now know that there are a very large number of small objects in the Kuiper Belt beyond the orbit of Neptune, some roughly the same size as Pluto More General Facts About Pluto Pluto has a satellite, Charon. Charon was discovered in 1978 In late 2005, two additional tiny moons were found to orbit Pluto (known as Nix and Hydra). They are estimated to be between 60 and 200 km in diameter Pluto's orbit is highly eccentric. At times it is closer to the Sun than Neptune (as it was from January 1979 thru February 11 1999) Pluto rotates in the opposite direction from most of the other planets Pluto's equator is at almost right angles to the plane of its orbit Comparison of Earth and Pluto Earth orbit: 149,597,871 km (1 AU) from the Sun diameter: 12,713 km mass: 5.9736 x 1024 kg Revolution: 365.25 days Rotation: 24 hours Rotational axis: tipped 23.5 degrees Pluto orbit: 5,913,520,000 km (39.5 AU) from the Sun diameter: 2274 km mass: 0.0125 x 1024 kg Revolution: 247.7 Earth years Rotation: 6.387 days Rotational axis: tipped 122 degrees Comparison of Earth and Pluto Pluto is smaller than seven of the solar system's moons (the Moon, Io, Europa, Ganymede, Calistoga, Titan and Triton) Missions to Pluto Pluto has not yet been visited by a spacecraft Even the Hubble Space Telescope can resolve only the largest features on its surface A spacecraft called New Horizons was launched in January 2006. If all goes well it should reach Pluto in 2015 Why Is It No Longer Considered a Planet? Due to additional objects being discovered including Eris (a dwarf planet in the Kuiper Belt) which is 27% more massive than Pluto, the IAU (International Astronomical Union) reclassified Pluto and the other objects as dwarf planets Kuiper Belt objects are comet-like in composition The Case For The Planet Pluto: -In addition to Pluto, there have been many other small planets discovered: Ceres, Eris, Makemake, Haumea, and many others. -Most of these (with the exception of Ceres in 1801) were discovered recently. -As technology improved and our knowledge of the Kuiper Belt objects grew, it became apparent that we could have many hundreds (if not thousands of planets). - In 2006, the International Astronomy Union (IAU) decided to create a definition for what a planet was. A Planet: 1. Orbits the sun. 2. Has enough mass to assume a nearly round shape. 3. Has cleared the area in its orbit. A Dwarf Planet: 1. Orbits the sun. 2. Also has enough mass to assume a nearly round shape. 3. Has NOT cleared the area in its orbit. 4. Is not a moon. Pluto Versus The Rest Of The Planets Characteristic Pluto Regular Planet Size Tiny Small to large Orbit Inclined 20o to ecliptic. Orbit crosses Neptune’s. Orbits close to ecliptic. Do not have orbits that cross. Shape Roughly spherical. Roughly spherical. Vicinity of orbit Orbit is shared with many other KBO’s Orbit is clear of major debris. The Verdict: Pluto is a dwarf planet!