Mark your calendar for Oct. 12. That's when asteroid 2012 TC4 will slip past Earth at an expected distance of around 27,300 miles (44,000 kilometers). The European Southern Observatory's Very Large Telescope in Chile recently caught sight of the asteroid, which could be up to 100 feet (30 meters) in size.
NASA is leading a coordinated international campaign to observe TC4 [umd.edu]. In July, NASA suggested [nasa.gov] the asteroid could squeeze in as close as 4,200 miles (6,800 kilometers), but the European Space Agency's latest estimates give us more breathing room.
Geosynchronous orbit [wikipedia.org] is at about 35,786 km above mean sea level.
Also at Phys.org [phys.org] (AFP).