Caption: Cover Page Image; GRL Special Section

Two arrows indicate the direction of the dramatic expansion of the Earth's
bowshock, between May 10 and 11, 1999. The lines give four instant locations of
the bowshock, and their colors, from red to light green-yellow, indicate the
gradual weakening of the bow shock strength as a function of the reduction of
the solar wind presence. Over-imposed on a map of the Earth, in the upper left
corner, a PIXIE/POLAR X-ray image of the magnetic north polar region shows an
unusual, nearly uniform, electron precipitation ("polar rain") on May 11, 1999.
In the bottom-right corner, an image of the Moon behind the solid green-yellow
line illustrates the extreme displacement of the bowshock, away from the Earth.

The Earth's bowshock passed 1st. Geotail (at 1645UT, 5/10, at ~27 Re from
Earth), 2nd. Interball-1 and its companion Magion-4 sub-satellite, seen behind,
(at 0047UT, 5/11, ~ 24 Re from Earth), 3rd. IMP-8, at 1115UT, ~ 33 Re from
Earth), 4th. Wind (at 1730UT, 5/11, ~52 Re from Earth), and 5th (and final) the
Lunar Prospector, which was orbiting the Moon (at 1733UT, 5/11, ~58 Re from