Abstract: The response of the Earth’s magnetosphere to the solar wind is highly sensitive to the orientation of the interplanetary magnetic field (IMF). Most effort over the last 50 years has been dedicated to understanding the behaviour of the magnetosphere during periods of “southward IMF”, which has, since the early days of the space age, been known to be correlated with periods of enhanced magnetic activity and auroral displays (e.g. substorms). However, the orientation of the IMF is highly changeable, and half of the time it is northward – the behaviour of the terrestrial system during periods of northward IMF is extremely poorly understood. Significant challenges in understanding the large-scale behaviour of the magnetospheric system remain for both northward and southward IMF orientations. In this seminar, we discuss recent progress in two aspects of large-scale magnetospheric dynamics. First, we discuss the formation of so-called high latitude auroras (polar cap arcs/transpolar arcs), which form during northward IMF, and their implication for the topological structure of the magnetosphere. Second, we discuss the previously-underestimated significance of bursty reconnection in driving the magnetosphere during periods of southward IMF.