EDITOR'S COMMENT: I don't know about anyone else, but don't these worthy of more than casual interest "close calls" seem to be occurring a little more frequently the last few years? Looking forward to March! Asteroid 2013 TX68 is a small asteroid with an uncertain trajectory that will pass close to Earth on March 5, 2016. Although the distance of its pass is not precisely known at this time, scientists say they will soon precisely define its orbit. It could fly past Earth as far away as 9 million miles (14 million km) or as close as 11,000 miles (17,000 km). For comparison, the moon's distance is about a quarter-million miles. Astronomers at NASA's Jet Propulsion Laboratory say the variation in possible distances for its closest approach is due to the wide range of possible trajectories for this object, which was tracked for only a short time after its discovery in 2013. Some estimates indicate the space rock may pass at 311,000 miles (500,505 km), which is about 1.3 Earth-moon