讲座时间：2019年1月9日 下午3：00-5：00
讲座嘉宾：Hao Cao, Harvard University
讲座题目：A magnetic perspective on the interiors of Saturn and Mercury
讲座地点：物理楼N415
Abstract
Magnetic fields are windows into planetary interiors. Among the eight solar system planets, six possess global-scale intrinsic magnetic fields at present. Recent observations from the MESSENGER mission, the Cassini mission, and the Juno mission revealed many surprising features in the internal magnetic fields of Saturn, Mercury, and Jupiter. These recent observations painted a new picture of solar system planetary magnetic fields. The magnetic fields of Mercury, Earth, Jupiter, and Saturn exhibit symmetry with respect to the spin-axis while the magnetic fields of Uranus and Neptune show no such symmetry. With respect to the equatorial plane, the magnetic fields of Earth and Saturn feature small but non-negligible asymmetries while the magnetic fields of Mercury and Jupiter show significant asymmetries. The magnetic fields of Uranus and Neptune likely possess similar strength in the two hemispheres divided by the equatorial plane, however, this needs to be tested with future measurements.
Here I will present the latest measurements and interpretations of the magnetic fields of Saturn and Mercury. For Saturn, I will report new features of Saturn’s magnetic field revealed by the Cassini Grand Finale including a newly discovered low-latitude inter-hemispherical field-aligned current (FAC) system, the directly determined northward offset of Saturn’s magnetic equator and its “longitudinal” variations, and small-scale magnetic structures along the latitudinal direction. For Mercury, with the help of numerical dynamo experiments I will show that the peculiar north-south asymmetry in Mercury’s magnetic field can be reconciled with extensive iron snow within Mercury’s liquid core and the slow rotation of Mercury. I will conclude by discussing the magnetic aspects of the ongoing Juno mission at Jupiter and the planned JUICE mission to orbit Ganymede.
Biography:
Education:
Ph.D. Geophysics and Space Physics, University of California, Los Angeles, Jun. 2014
M.S. Geophysics and Space Physics, University of California, Los Angeles, Jun. 2011
B.S. Geophysics and Space Physics, Univ. of Sci. and Tech. of China, Jun. 2009
Academic Appointments:
Research Associate, Harvard University, Sep. 2017 – present
Postdoctoral Scholar in Planetary Science, California Institute of Technology, Aug. 2014 – Sep. 2017
Postdoctoral Scholar, University of California, Los Angeles, Jun. 2014 – Aug. 2014
Graduate Student Researcher, University of California, Los Angeles, Sep. 2009 – Jun. 2014
Research Interests:
Understanding the interior structure, dynamics, and evolution of planetary bodies.
Planetary magnetism and planetary dynamos, including the geodynamo.
Gravitational and electromagnetic interactions between giant planets and rings.
Gravitational and electromagnetic sounding of planetary interiors.
Participation in Space Missions:
Co-Investigator, JUICE MAG Team, Jan. 2016 – present
Cassini Participating Scientist, Cassini Mission, Mar. 2015 – Sep. 2017
Member, Juno Interior Working Group, Aug. 2014 – present
Member, Cassini MAG Team, Jun. 2014 – present
Associate, Cassini MAG Team, Jan. 2010 – Jun. 2014
Honors and Awards:
Eugene B. Waggoner Scholarship, UCLA, Sep. 2012
NASA Earth and Space Science Fellowship, NASA, May 2012
