Scientists are urging people not to panic after learning a 30m-wide asteroid could be about to brush by the Earth at a distance close enough to threaten orbiting satellites.
The space rock, named 2013 TX68, is expected to make its nearest approach to Earth early this month.
But the precise timing of its visit and trajectory will not be known until after the event.
The asteroid could shoot past the Earth inside the ring of communications and GPS satellites located in fixed positions 35,900km above the equator, experts say.
At the other limit of its predicted path range it could remain as far out as 40 times the distance to the moon.
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US scientist Sean Marshall, from Cornell University in New York, who studies near-Earth objects such as comets and asteroids said it would be rare for the rock to come closer than geostationary satellites.
"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," he said.
"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."
Geostationary satellites all circle the equator and have orbits that match the rotation of the Earth, so they remain above one fixed point.
They are much further away than the International Space Station, which circles the Earth at an altitude of about 400km.
