An astronomer at the Institute of Astronomy (IfA) at the University of Hawaii has revealed new critical discoveries related to a large asteroid that is expected to pass very close to Earth. Dave Tholen and colleagues announced the detection of Yarkovsky’s acceleration in the asteroide Apophis that is close to Earth.
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 likelihood of an impact with Earth in 2068.
All asteroids need to re-radiate the heat of the energy they absorb from sunlight to maintain thermal balance, a process that slightly alters the asteroid’s orbit. Before detecting Yarkovsky’s acceleration in Apophis, astronomers 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 trajectory to Earth on Friday, April 13, 2029, when the 300-meter space rock will become visible to the naked eye as it passes within the belt of orbiting communication satellites the land.
Tholen, who has been accurately tracking the movement of Apophis in the sky since his team discovered it in 2004, reported:
We have known for some time that an impact with Earth is not possible during the approach of 2029. The new observations we obtained with the Subaru telescope earlier this year were good enough to reveal Apophis’s Yarkovsky acceleration, and they show that the asteroid it is moving away from a purely gravitational orbit at about 170 meters a year, which is enough to keep the 2068 impact scenario at stake.
The orbit calculations were performed by Davide Farnocchia from Jet Propulsion Laboratory, who is co-author of the article presented at the 2020 virtual meeting of the Planetary Science Division of the American Astronomical Society.
The width of the “rock” is 304 meters. The fall will be tantamount to an explosion of 880 million tons of trinitrotoluene. The body was discovered on June 19, 2004 by specialists from the Kitt Peak National Observatory (Arizona). Apophis moves in an orbit around the star, making a complete revolution in almost an Earth year.
Further observations to refine the breadth of the Yarkovksy effect and how it affects the Apophis orbit are underway. Astronomers will know well before 2068 if there is any chance of impact.