The moving Martian bow shock

A Lancaster physicist has led an international study, based on data from the European Space Agency Mars Express orbiter , which throws new light on the interaction between the planet Mars and supersonic particles in the solar wind. As the energetic particles of the solar wind speed across interplanetary space, their motion is modified by objects in their path. Scientists have long been aware that a feature known as a bow shock forms upstream of a planet - rather like the bow of a ship, where the water is slowed and then diverted around the obstacle. A team of European scientists has investigated how and why the bow shock's location varies during the Martian year. In a paper published in the Journal of Geophysical Research: Space Physics , the team has analysed more than five Martian years of measurements from the Mars Express Analyser of Space Plasma and EneRgetic Atoms (ASPERA-3) Electron Spectrometer (ELS) to identify 11,861 bow shock crossings. This is the first analysis of the bow shock to be based on data obtained over such a prolonged period and during all Martian seasons. The scientists discovered that, on average, the bow shock is closer to Mars near aphelion (the planet's furthest point from the Sun), and further away from Mars near perihelion (the planet's closest point to the Sun).