Trick of the Tail
Our peculiar motion through the local void does not proceed unnoticed. As the sun speeds through the Galaxy, dragging its planets behind, it produces a tail behind it like a comet streaking across the sky. Though long predicted, scientist now have the first definitive measurement of this "heliotail", thanks to NASA's Interstellar Boundary Explorer, or IBEX. This tail is nearly impossible to see directly, so astronomers use a clever trick. As the sun moves through interstellar space, the solar wind gets bent around behind it. The collision of the fast-moving, ionized solar wind with slower particles from interstellar space produces a population of fast moving neutral atoms through a process called charge exchange. As it scans the sky, IBEX provides maps of these energetic neutral atoms and so is able to measure the boundary of the heliotail. An artist conception of what this tail might look like is ahown above. The heliotail shows the path of the sun through the Galaxy; how far this path extends, IBEX cannot say.
Published: July 22, 2013
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Page Author: Dr. Michael F. Corcoran
Last modified Monday, 29-Jul-2013 03:31:36 EDT