A 100FT-wide asteroid is heading for a close encounter with Earth tomorrow and could come closer than some orbiting satellites.

But scientists are confident it will miss the Earth by at least 15,000 miles, and say there is no need to panic.

The space rock, named 2013 TX68, was spotted three years ago by astronomers in the US scouring the skies for potentially threatening near-Earth objects (NEOs).

Because it was tracked for only 10 days, its orbital path is uncertain. Experts believe it will make its closest approach to Earth tomorrow, although the forecast might be one or two days out.

Calculations show that 2013 TX68 could shoot past the Earth well within the ring of geostationary communications and GPS satellites stationed 22,300 miles above the equator.

At the other limit of its predicted range it could remain as far out as 40 times the distance to the moon.

US astronomer Sean Marshall, from Cornell University in New York, who studies NEOs such as comets and asteroids, said: “Should this large asteroid come closer than the geostationary satellites, it would be a rare occurrence – that only happens about once per decade for large asteroids.”