No. 123: May-Jun 1999
A chunk of "something" about 50 meters across plays tag with the earth as it circles the sun. Discovered February 10, 1999 by an automated, asteroid-hunting telescope in New Mexico, the object's official name is 1999 CG9. Its orbit is nearly circular and 9 million kilometers farther away from the sun than the earth. Its year is 1.09 earth years.
"The object's orbit is extremely unusual. Comets and asteroids that cross the earth's orbit normally have eccentric orbits. There is only one asteroid-like object, called 1991 VG, that has an similar orbit to that of earth. When it was discovered eight years ago, astronomers thought it might be a spacecraft that had escaped the earth's gravity."
However, newly discovered 1999 CG9 is much too large to be a wayward piece of space hardware. The best guess is that it is a piece of the moon that was knocked off by an impacting asteroid.
(Hecht, Jeff; "Chip off the Moon," New Scientist, p. 13, February 27, 1999.)
Comment. Might it not be a chip off the earth itself? Or perhaps space hardware from somewhere else?!