Sentence under Planetary Science Webinar Part 5

Planetary Science 2014 – Part 5 Triton is a moon of Neptune. The information for Triton is less extensive because it has not been visited by many missions. For Jupiter and Saturn the Voyager missions were followed by Cassini to Saturn and Galileo to Jupiter. The Voyager mission has been the only mission to Neptune and Triton, and that was several years ago – in the 1980’s. Triton is actually a captured Kuiper Belt object. Its motion is retrograde and the polar regions face the Sun. It is an odd moon but still has some interesting surface features. It is -400 degrees on Triton – really cold; however, geysers were discovered by Voyager and are ejecting organics and nitrogen. There are also debris plumes formed by the geysers, just like the sand jets in the south polar region of Mars. Some kind of tidal stress and flexing is producing the geysers and the resulting debris plumes, which again show the velocity and direction of surface winds on Triton. This is an artist illustration of the geysers and plumes on Triton. Ceres is the largest asteroid, and the only minor planet in the inner part of the Solar System. It is of interest because of its size and it is thought that Ceres has a large water-ice layer under its thing and dusty outer crust. In 2015 a mission has been planned to have a close encounter with this object to study its interior. Comets occasionally visit the vicinity of the Earth, and we encounter monthly meteor showers which are the materials left behind in the orbits of defunct and active comets. In 1994 Comet Shoemaker-Levy got caught in the gravitational field of Jupiter, broke up, and disappeared into the Jovian atmosphere. Again in 1997 when Comet Hale-Bopp passed by, disconnection events were observed that showed materials from the comet being left behind in its orbit. As the early Earth was forming, and before it had an atmosphere, many materials from comets were deposited on the surface of Earth. Amino acids were once thought to have formed on Earth, but evidence now shows that they were formed in space and brought to Earth by comets and meteors. Very complex carbohydrates and other molecules have been found, such as Bucky balls in meteor craters and amino acids, glycerin, alcohol and other organics in comets. Comets originate in the Oort cloud, a spherical area of materials left behind by the collapse of the Solar System into a disc shape when the Sun formed out of a condensing spherical cloud of gas and dust. The material is pristine - unchanged since the formation of the Sun and Solar System, and studying this material will give information as to the conditions in the early Solar System. Comets are also found in the Kuiper Belt which forms a ring of materials between the orbits of Neptune and the outermost orbit of Pluto. These short term comets are confined to the disc of the Solar System whereas Oort cloud comets enter the Solar System from any direction. Remember this event focuses on the history and processes of the formation of specific features and landforms in the Solar System. This is an artist illustration of what a sub-surface glacier looks like in the equatorial region of Mars. The glacier would produce the lobate debris apron above it on the Martian surface. Earth has these same features that are caused by the movement of glaciers.