The asteroid 2013 TX68 will come fairly close to Earth in early March, but the exact time and distance of its closest approach will not be known until after the fact.

Sean Marshall, a fifth-year Cornell University PhD student, works on observations of near-Earth asteroids. He says the closest approach could be within Earth's 'ring' of geostationary satellites, or it could be as far out as 40 times the distance to the Moon.

Marshall says, "2013 TX68 is estimated to be about 100 feet in diameter. Its closest approach could be within Earth's 'ring' of geostationary satellites, or it could be 40 times the distance to the Moon - or anywhere in between.

"Should this asteroid come closer than the geostationary satellites, it would be a rare occurrence - that only happens about once per decade for large asteroids. What we know for sure is that it will not collide with Earth this month, so do not panic."

"The large uncertainty in TX68's orbit makes it difficult to plan observations in advance, but hopefully it will be seen by some of the automated asteroid survey telescopes.

"However, it is possible that TX68 will be so far from Earth that it will be too faint to be seen.

"If TX68 is detected this month, that would greatly reduce the uncertainty in its orbit and allow astronomers to calculate its future trajectory much more accurately."