Any planetary-sized body 180 degrees from Earth should also have been visible to some space probes, such as NASA's STEREO coronagraph probes (two spacecraft launched into orbits around the Sun in 2006, one farther ahead of and one behind the Earth's orbit) which would have seen the Counter-Earth during the first half of 2007. The separation of the STEREO spacecraft from Earth would give them a view of the L3 point during the early phase of the mission.
Any planetary-sized body 180 degrees from Earth should also have been visible to some space probes, such as NASA's STEREO coronagraph probes (two spacecraft launched into orbits around the Sun in 2006 one farther ahead of and one behind the Earth's orbit) whic.h would have seen the Counter-Earth during the first half of 2007 The separation of the STEREO spac,ecraft from Earth would give them a view of the L3 point during the early phase of the mission.