Mar. 11, 2010 Distant galaxy clusters mysteriously stream at a
million miles per hour along a path roughly centered on the
southern constellations Centaurus and Hydra. A new study led by
Alexander Kashlinsky at NASA's Goddard Space Flight Center in
Greenbelt, Md., tracks this collective motion -- dubbed the
"dark flow" -- to twice the distance originally reported. "This
is not something we set out to find, but we cannot make it go
away," Kashlinsky said. "Now we see that it persists to much
greater distances -- as far as 2.5 billion light-years away."
The new study appears in the March 20 issue of The Astrophysical
Journal Letters. The clusters appear to be moving along a line
extending from our solar system toward Centaurus/Hydra, but the
direction of this motion is less certain. Evidence indicates
that the clusters are headed outward along this path, away from
Earth, but the team cannot yet rule out the opposite flow. "We
detect motion along this axis, but right now our data cannot
state as strongly as we'd