The asteroid, which was the reason behind the extinction of dinosaurs, may have been two rocks orbiting one another.
Scientists have said that the asteroid normally thought of as a single rock with a diameter of 7 - 10 kilometres, could have been two rocks with the combined diameter, New Scientist reported.
The surprise claim comes from a reassessment of the proportion of asteroid craters on Earth - formed by binary impacts.
Katarina Miljkovic from the Institute of Earth Physics in Paris, France, and her colleagues ran computer simulations of binary asteroids hitting Earth and they found that the two asteroids often created a single crater.
The simulations suggested that the craters that were subtly asymmetrical like the crater near Chicxulub in Mexico - thought to be the result of an asteroid impact 65.5 million years ago that wiped out the dinosaurs - could have had binary origins.
Miljkovic's said that the twin asteroids could have been up to 80 kms apart. (ANI)