According to a report in The Sun, the object - named P/2010 A2 - is of a type never before seen by stargazers and orbits in a satellite belt between Mars and Jupiter.
Despite its tail, scientists have ruled out it being a comet, as there is no gas in its trail.
The 140-metre nucleus is also offset from the centre of the tail and its structure is very unusual.
The most likely theory is that it is debris from a collision between two asteroids which were likely to have smashed together at a speed of 15,000 kilometres an hour, five times the speed of a rifle bullet.
The resulting collision would have released more energy than a nuclear bomb.
It is believed that pressure from sunlight then spread the debris out into a trail.
"Future study of P/2010 A2 may better indicate the nature of the original collision and may help humanity better understand the early years of our Solar System, when many similar collisions occurred," said Dr Robert J Nemiroff, astrophysicist at Michigan Technological University and the NASA Goddard Space Flight Center.
"What Hubble saw indicates that P/2010 A2 is unlike any object ever seen before. At first glance, the object appears to have the tail of a comet," he said.
"Close inspection, however, shows a 140-metre nucleus offset from the tail centre, very unusual structure near the nucleus, and no discernable gas in the tail," he explained.
"Knowing that the object orbits in the asteroid belt between Mars and Jupiter, a preliminary hypothesis that appears to explain all of the known clues is that P/2010 A2 is the debris left over from a recent collision between two small asteroids," said Nemiroff.
"If true, the collision likely occurred at over 15,000 kilometres per hour, five times the speed of a rifle bullet, and liberated energy in excess of a nuclear bomb. Pressure from sunlight would then spread out the debris into a trailing tail," he added.The mysterious object was circling about 90million miles (144million km) away from Earth when it was spotted.