The Shaw Prize Lecture in astronomy 2022: Journey of Space Astrometry- Mapping the positions and motions of stars from space
◎Why Are We Measuring Star Positions From Space?
The speaker will first look at the scientific aspects of this exciting journey. Firstly, he will put their modern space measurements in the historical context and summarise what astronomers have learnt from measuring star positions over the past few hundred years. After that, a few of the remarkable scientific advances which are resulting from the extremely accurate measurements of star positions from space, and also a little of what this is telling us about our place in the Universe will be covered.
講者：Prof. Michael PERRYMAN(Adjunct Professor, School of Physics, University College, Dublin, Ireland; Study Scientist and Project Scientist for the Gaia mission; Project Scientist for the Hipparcos mission)
◎Fundamental Concepts For Global Astrometry
The speaker will describe how optical observations using a scanning satellite allow us to measure accurate absolute parallaxes and proper motions, and to build a rigid reference frame over the whole celestial sphere. The principle was first applied to Hipparcos data in the 1990s, and the same principle is now used for Gaia. The intertwined measurements of all objects bring formidable data-processing challenges that could not be mastered for Hipparcos without certain approximations. The exponential growth in computing power since then makes it possible to treat the Gaia data much more rigorously, in spite of the immensely larger data volume.
講者：Prof. Lennart LINDEGREN(Professor Emeritus, Department of Astronomy and Theoretical Physics, Lund Observatory, Lund University, Sweden; Member of the Gaia Science Team; Member of the Royal Swedish Academy of Sciences)
主持：Dr Man Hoi LEE(Head and Associate Professor, Department of Earth Sciences, Faculty of Science, HKU)