New York, Nov 9 (IANS): Astronomers have revealed that large asteroid named 'Apophis' expected to pass extremely close or may hit the Earth in 2068 due to a phenomenon called Yarkovsky effect.

Researchers at University of Hawaii Institute for Astronomy (IfA) in the US, have announced the detection of Yarkovsky acceleration on the near-Earth asteroid Apophis.

This acceleration arises from an extremely weak force on an object due to non-uniform thermal radiation.

This force is particularly important for the asteroid Apophis, as it affects the probability of an Earth impact in 2068, the astronomers said.

"All asteroids need to reradiate as heat the energy they absorb from sunlight in order to maintain thermal equilibrium, a process that slightly changes the orbit of the asteroid," they wrote.

Prior to the detection of Yarkovsky acceleration on Apophis, astronomers had concluded that a potential impact with Earth in 2068 was impossible.

The detection of this effect acting on Apophis means that the 2068 impact scenario is still a possibility.

Apophis is noteworthy because of its extremely close approach to the Earth on April 13, 2029, when the 300 metre-sized asteroid will become visible to the unaided eye as it passes within the belt of communications satellites orbiting the Earth.

The new observations we obtained with the Subaru telescope earlier this year were good enough to reveal the Yarkovsky acceleration of Apophis.

It shows that the asteroid is drifting away from a purely gravitational orbit by about 170 metres per year, which is enough to keep the 2068 impact scenario in play.

Further observations to refine the amplitude of the Yarkovksy effect and how it affects Apophis' orbit are underway.

Astronomers will know well before 2068 if there is any chance of an impact.

Their study was presented at the 2020 virtual meeting of the Division for Planetary Sciences of the American Astronomical Society.

Earlier in August, SpaceX CEO Elon Musk had also predicted that huge asteroid Apophis will eventually hit the humanity and there will be no way out.

"Great name! Wouldn't worry about this particular one, but a big rock will hit Earth eventually & we currently have no defence," he wrote on social media platform.