Will asteroid Apophis hit Earth in 2068? Experts unsure but study says it’s speeding up as it heads toward us
The asteroid Apophis, which is about the size of three-and-a-half football fields, is speeding up as it heads towards Earth, according to scientists. This may increase its chances of hitting Earth in 2068. Researchers from the University of Hawaiʻi Institute for Astronomy (IfA) explain that this could be due to non-uniform thermal radiation which can act like a mini-thruster.
Further explaining, the research team says that the new observations reveal that the asteroid is under the influence of the “Yarkovsky effect.” Rotating asteroids have a tough time sticking to their orbits. Their surfaces heat up during the day and cool down at night, giving off radiation that can act as a sort of mini-thruster. This force, called the Yarkovsky effect, can cause rotating asteroids to drift widely over time, making it hard for scientists to predict their long-term risk to Earth. It can also accelerate or decelerate the current speed of the asteroid. To learn more about this process on asteroid Bennu, NASA sent a spacecraft called OSIRIS-REx to make detailed observations of Bennu’s shape, brightness and surface features.
“(The investigators) 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,” say authors who presented the findings at the 2020 virtual meeting of the Division for Planetary Sciences of the American Astronomical Society. According to NASA, current calculations show that Apophis still has a small chance of impacting Earth, less than 1 in 100,000 many decades from now, but future measurements of its position can be expected to rule out any possible impacts.
The latest observations
The asteroid was discovered on June 19, 2004, by astronomers Roy Tucker, David Tholen, and Fabrizio Bernardi at the Kitt Peak National Observatory in Tucson, Arizona. Before 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, emphasizes the team.
“We have known for some time that an impact with Earth is not possible during the 2029 close approach. The new observations we obtained with the Subaru telescope earlier this year were good enough to reveal the Yarkovsky acceleration of Apophis, and they show that the asteroid is drifting away from a purely gravitational orbit by about 170 meters per year, which is enough to keep the 2068 impact scenario in play,” explains Tholen, who announced the detection of Yarkovsky acceleration. Tholen has been tracking the motion of Apophis in the sky since 2004. Further observations to refine the amplitude of the Yarkovsky effect and how it affects Apophis’ orbit are underway. Astronomers will know well before 2068 if there is any chance of an impact, say researchers.
It'll harmlessly cruise by Earth on April 13, 2029
Apophis is a 1,120-foot-wide (340-meter-wide) asteroid. It is named after the demon serpent who embodied evil and chaos in ancient Egyptian mythology. After its discovery, the asteroid caused a stir because initial calculations indicated a small possibility it would impact Earth in 2029. The most important observations of Apophis are expected to come during its close Earth flyby: scientists around the world will study the asteroid’s size, shape and composition.
However, scientists subsequently ruled out the possibility of a 2029 impact. It is now predicted the asteroid will harmlessly pass close to Earth on April 13, 2029, about 19,800 miles (31,900 kilometers) from our planet’s surface. While that is a safe distance, it is close enough that the asteroid will come between Earth and the Moon, which is about 238,855 miles (384,400 kilometers) away. Astronomers say that it is rare for an asteroid of this size to pass so close to Earth, although smaller asteroids, in the range of 16 to 33 feet (5 to 10 meters), in size have been observed passing by at similar distances.
During its 2029 flyby, Apophis will first become visible to the naked eye in the night sky over the southern hemisphere and will look like a speck of light moving from east to west over Australia. It will be mid-morning on the US East Coast when Apophis is above Australia. The asteroid will then cross above the Indian Ocean, and continuing west, it will cross the equator over Africa. At its closest approach to Earth, just before 6 pm EDT on April 13, 2029, Apophis will be over the Atlantic Ocean. According to astronomers, it will move so fast that it will cross the Atlantic in just an hour. By 7 pm EDT, the asteroid is expected to have crossed over the US.