Astronomers discovered the asteroid Apophis back in 2004. Soon after, the researchers calculated its orbital trajectory and found that an object weighing 2.7 * 1010 kilograms and a radius of about 185 meters would pass near the Earth in 2013, 2029, 2036 and 2068.
Further research showed that the risk of an asteroid colliding with Earth was vanishingly small; thus, Apophis was not considered a threat to our planet. However, a study by the American astronomer David Tholen and his colleagues showed that the asteroid should be treated with more caution. Tholen outlined his considerations in a talk delivered during an online meeting of the American Astronomical Society’s Division of Planetary Sciences.
Tholen and his colleagues noted that earlier researchers did not take into account the so-called Yarkovsky effect, in which the sun’s rays fall on one side of the asteroid. This leads to the appearance of a reactive impulse due to the heating and cooling of this side and gives the celestial body additional acceleration.
This effect leads to the fact that Apophis deviates from the calculated trajectory by about 170 meters per year. In this case, the asteroid is gradually approaching our planet. Consequently, the probability of its collision with the Earth is slightly higher than previously assumed.
Tholen believes that in 2029 and 2036, the risk of an asteroid collision with a planet remains purely mathematical. But the passage of Apophis by the Earth in 2068 may turn into a catastrophe on a planetary scale – and it is worth somehow preparing for this. Studying Apophis as it approaches in 2029 should give scientists a more complete idea of whether this object will threaten humanity 39 years later.
In 2013, Apophis approached our planet at a distance of 14 million and 460 thousand kilometers (ten times less than from the Earth to the Sun). According to calculations, in 2029 a guest from distant space will be much closer: the distance to him at the point of closest approach will be from 31 to 38 thousand kilometers, and Apophis can be seen from Earth with the naked eye.