The asteroid, which is 400 metres wide, was spotted by astronomers in Hawaii on October 10 and is said to be travelling at 22 miles per second.
At that rate, it is expected to quickly whizz past Earth at 5pm today.
Dr Marco Micheli, an astronomer from ESA's NEO Co-ordination Centre in Italy, said: "The diameter of about 400 metres has a large uncertainty, as is usual in cases of any object for which we do not yet know details, such as its composition.”
Scientists estimate there are 5,000 NEOs of similar size hurtling through Earth's region of the solar system - a significant number of which have not yet been discovered.
Dr Koschny added: "Objects of this size are often spotted by automated surveys.
"The only difference is that, being so large, they are often found when they are quite far away, out to 2.5 times the sun-Earth distance, and not just before a close approach, as in this case."
