Asteroid Phaethon is rotating faster and faster

Astronomers analyzed the behavior of the asteroid Phaethon and came to the conclusion that the period of its rotation around its axis decreases by 4 seconds per year. By 2024, the Japanese DESTINY+ automatic probe should go to it.

The artist’s idea of the asteroid Phaethon. Source:

Asteroid Phaethon accelerated its rotation

Sean Marshall, a planetary scientist at the Arecibo Observatory in Puerto Rico, recently published a study of the period of rotation of the asteroid Phaethon around its axis. The orbit of this celestial body lies quite close to the Sun and the Earth. It is considered potentially dangerous, but there is no immediate threat of collision with it.

Marshall analyzed the observation of the asteroid between 1989 and 2021 and tried to create a model of its shape and the rotation that takes place. Depending on which side the Phaethon turns to the Sun, the area of the illuminated surface changes and, as a result, its apparent brightness in the sky. 

But it turned out that the observed data did not coincide with the uniformly rotating model of the space rock. It is possible to explain the change in the brightness of the Phaethon only if its rotation is constantly accelerating.

Scientists have calculated that the Phaethon’s circulation period decreases by 4 milliseconds per year. Most likely, this is due to cometary activity that occurs when it approaches the Sun. The evaporation of gases gives an impulse, which leads to this effect.

DESTINY+ Mission

Phaethon is only the eleventh asteroid to have an acceleration of rotation through cometary activity. It approaches the Sun at a distance of only 21 million km and materials that usually do not participate in cometary activity begin to evaporate from its surface.

Among all the space stones that demonstrate such acceleration of rotation, it is the largest. The diameter of the Phaethon is 5.4 km. In addition, it is the bluest asteroid known to humans. And this is also due to its proximity to the Sun.

By 2024, Japan should launch a DESTINY+ probe to it. It will make several revolutions around the Sun and in 2028 will get closer to Phaethon. And it is very important for him to accurately predict which sides of the asteroid will be illuminated by the Sun.

According to

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