|1. 学术报告：Ceres(谷神星) - The Nearest Icy Planet from Earth?|
单位：美国Planetary Science Institute
摘要 The discovery of Ceres in 1801 marked the start of a new era in planetary science. A large population of asteroids were discovered since, opening a whole new territory in the Solar System where astronomers are able to directly observe the building blocks of our planetary system. The exploration of Ceres by the Dawn mission will probably start another new era, when a possible icy planet is revealed in the asteroid belt, where we previously considered to be too hot for a large amount of water to exist. With about 1/4 of its mass in water that was liquid in the past and probably even today beneath the surface, Ceres is the largest reservoir of water closest to Earth. Water is a sensitive probe to temperature and pressure and other physical conditions for the formation and evolution of planetesimals, and an important medium for geochemistry. It also has significant implications for habitability. Therefore, the current status and the evolutionary history of water in the solar system, especially in the location between the hot, dry inner solar system and cold, wet outer solar system is the key to understand the formation of our planetary system. Ceres and its history of water certainly mark the entry to this key territory. I will introduce Ceres in the context of asteroid science, present some of the most important findings by Dawn, and discuss the implications for understanding the origin and evolution of solar system.
李荐扬，美国Planetary Science Institute 资深研究员。1999年毕业于中国科大物理系获学士学位，2005年获美国马里兰大学天文系博士学位。长期从事小行星和慧星的探测与研究。是美国NASA DAWN mission extended phase的Co-I，是Deep Impact，DIXI，Stardust-NExT，OSIRIS-REx等探测计划的科学组成员。于2011, 2013, 2015年三次获NASA集体成就奖。小行星21496(1998 JQ2)以他的名字命名。