Magnetic holes are curious localized dropouts of magnetic field strength in the solar wind (the flow of ionized gas continuously streaming out from the sun). In this paper we show that these magnetic holes can cross the bow shock (where the solar wind brake down to subsonic velocity) and enter the region close to Earth’s magnetosphere. These structures may therefore represent a new type of non-uniform solar wind–magnetosphere interaction.

Boundaries in the plasma around comet 67P separate regions with different properties. Many have been identified, including a new boundary called an infant bow shock. Here, we investigate how the plasma and fields behave at this boundary and where it can be found. The main result is that the infant bow shock occurs at intermediate activity and intermediate distances to the comet. Most plasma parameters behave as expected; however, some inconsistencies indicate that the boundary is non-stationary.

When the magnetised solar wind meets the plasma surrounding a comet, the magnetic field is enhanced in front of the comet, and the field lines are draped around it. This happens because electric currents are induced in the plasma. When these currents flow through the plasma, they can generate waves. In this article we present observations of ion acoustic waves, which is a kind of sound wave in the plasma, detected by instruments on the Rosetta spacecraft near comet 67P/Churyumov–Gerasimenko.

The Earth's atmosphere is constantly losing molecules and charged particles, amongst them oxygen ions or O⁺. Quantifying this loss provides information about the evolution of the atmosphere on geological timescales. In this study, we investigate the final destination of O⁺ observed with Cluster satellites in a high-altitude magnetospheric region (plasma mantle) by tracing the particles forward in time using simulations. We find that approximately 98 % of O⁺ escapes the Earth's magnetosphere.

In this paper we have used Cluster EDI data in combination with the CODIF cusp dataset from Slapak et al. (2017) to obtain parallel and convection velocities for oxygen ions; 69 % of total oxygen outflow from the high-altitude cusps escapes the magnetosphere on average; 50 % escapes tailward beyond the distant X-line. The oxygen capture-versus-escape ratio is highly dependent on geomagnetic conditions. During active conditions, the majority of oxygen outflow is convected to the plasma sheet.