As Earth moves around the sun, it travels surrounded by a giant bubble created by its own magnetic fields, called the magnetosphere. As the magnetosphere plows through space, it sets up a standing bow wave or bow shock, much like that in front of a moving ship. Just in front of this bow wave lies a complex, turbulent system called the foreshock. Conditions in the foreshock change in response to solar particles streaming in from the sun, moving magnetic fields and a host of waves, some fast, some slow, sweeping through the region.

To tease out what happens at that boundary of the magnetosphere and to better understand how radiation and energy from the sun can cross it and move closer to Earth, NASA launches spacecraft into this region to observe the changing conditions. From 1998 to 2002, NASA’s Wind spacecraft traveled through this foreshock region in front of Earth 17 times, providing new information about the physics there.

via NASA – NASA’s Wind Mission Encounters ‘SLAMS’ Waves.

This artist’s concept illustrates how charged water particles flow into the Saturnian atmosphere from the planet’s rings, causing a reduction in atmospheric brightness. Image credit: NASA/JPL-Caltech/Space Science Institute/University of Leicester

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A new study tracks the “rain” of charged water particles into the atmosphere of Saturn and finds there is more of it and it falls across larger areas of the planet than previously thought. The study, whose observations were funded by NASA and whose analysis was led by the University of Leicester, England, reveals that the rain influences the composition and temperature structure of parts of Saturn’s upper atmosphere. The paper appears in this week’s issue of the journal Nature.

“Saturn is the first planet to show significant interaction between its atmosphere and ring system,” said James O’Donoghue, the paper’s lead author and a postgraduate researcher at Leicester. “The main effect of ring rain is that it acts to ‘quench’ the ionosphere of Saturn. In other words, this rain severely reduces the electron densities in regions in which it falls.”

O’Donoghue explains that the ring’s effect on electron densities is important because it explains why, for many decades, observations have shown those densities to be unusually low at certain latitudes on Saturn. The study also helps scientists better understand the origin and evolution of Saturn’s ring system and changes in the planet’s atmosphere.

via NASA – Blame it on the Rain (from Saturn’s Rings).