In addition, the collision with a 372 - kilogram (820 - pound) projectile launched by NASA's Deep Impact probe in 2005 has
created a 150 - meter - wide (490 - foot - wide) crater with a
small mound in the center, as some of the ejecta of the impact apparently fell back down within the crater, but the crater's relatively soft outline indicates that its edges have undergone significant changes since the 2005 impact (NASA / STARDUST / NExT news release; Astronomy Picture of the Day; David Shiga, New Scientist, February 15, 2011; Jonathan Amos, BBC News, February 15, 2011; and Richard A. Lovett, Nature News, February 15, 2011).