Astronomers predict second Earth Moon

[vinin]

International group of scientist just submitted their findings to the journal Icarus. Preprint is available at _http://arxiv.org/abs/1112.3781. According to the computer modeling and astronomical observation at any given time Earth has at least one temporary natural satellite, essentially second moon.

The population of natural Earth satellites
Authors: Mikael Granvik, Jeremie Vaubaillon, Robert Jedicke
(Submitted on 16 Dec 2011)
Abstract: We have for the first time calculated the population characteristics of the Earth's irregular natural satellites (NES) that are temporarily captured from the near-Earth-object (NEO) population. The steady-state NES size-frequency and residence-time distributions were determined under the dynamical influence of all the massive bodies in the solar system (but mainly the Sun, Earth, and Moon) for NEOs of negligible mass. To this end, we compute the NES capture probability from the NEO population as a function of the latter's heliocentric orbital elements and combine those results with the current best estimates for the NEO size-frequency and orbital distribution. At any given time there should be at least one NES of 1-meter diameter orbiting the Earth. The average temporarily-captured orbiter (TCO; an object that makes at least one revolution around the Earth in a co-rotating coordinate system) completes $(2.88\pm0.82)\rev$ around the Earth during a capture event that lasts $(286\pm18)\days$. We find a small preference for capture events starting in either January or July. Our results are consistent with the single known natural TCO, 2006 RH$_{120}$, a few-meter diameter object that was captured for about a year starting in June 2006. We estimate that about 0.1% of all meteors impacting the Earth were TCOs.

I am wondering if those are not really natural objects and have some purpose.

 

[mkrnhr]

As you can read from the abstract, the article deals with natural objects that get captured from time to time.

 

[vinin]

As you can read from the abstract, the article deals with natural objects that get captured from time to time.

Yes, that what the authors presume. Even if they are natural as comets and meteors are. Are they random? We know meteors influenced history in the past. And it is convenient to have one around all the time. I do not suggest though that a natural object could suddenly change its orbit and impact the Earth.
Anyway I thought it was interesting to know.