Detlev Van Rawenswaay / Science Photo Library

On 12 October 2012, 5:30 UTC, an asteroid 2012 TC4 (which I discussed earlier) made a close approach at 95 000 km from Earth. Its photometric observations were conducted at out observatory 24 hours before the closest approach. During the observations, the asteroid got closer to our planet from 583 400 to 508 600 kilometers. Accuired data allowed to estimate its rotational period, which is 12.2 minutes. More detailed data, as well as the magnitude graph, will be published in the Minor Planet Bulletin. Fast rotation of such small cosmic bodies that come close to Earth is common, and serves as proof of their origin from collisions. I should note that the period of 12.2 minutes isn’t the shortest among asteroids observed at ISON-NM observatory. For example, rotation period of another asteroid – 2012 KP24 is just 2.5 minutes! Absolute record at the moment belongs to the asteroid 2010 TD54, it makes a full rotation in just 42 seconds!

The analysis of evolution of the orbit of asteroid 2012 TC4 during its close approach to Earth shows that its orbit was affected by the gravitational influence of the Earth-Moon system. In the XY plane (in this case the ecliptic plane), the asteroid’s orbit was deflected by ~13 degrees from its original direction. The orbital period of 2012 TC4 around the Sun increased by 20%, from 1.45 to 1.74 years. The graph below shows this. The next close approach of this asteroid with Earth will happen in 5 years.

Translation by Maksim Kakitsev.

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