Earth at any given time, has more than one moon. That was the conclusion a team of astronomers from the University of Helsinki, the Paris Observatory and the University of Hawaii at Manoa.
Our moon is 3,200 kilometers in diameter, sung by poets, singers and romance revolves around the Earth for over 4 billion years. Her younger sister, named mililunami do not exceed a few meters in size and orbit the planet is not more than a year, and then return to orbit near, like asteroids.
Macael Gravnik (Helsinki), Jeremy Vaubayllon (Paris) and Robert Dzhedike (Manoa) calculated the probability that at any given time, in Earth orbit is more than one natural satellite. They are modeled on the computer pass near Earth asteroid 10 million. Were then calculated the trajectory 18,000 objects captured by Earth’s gravity.
They concluded that at any time to be rotated around the earth at least one asteroid with a diameter of at least one meter. Of course, at the Earth’s orbit and may be a large number of smaller objects.
As demonstrated by the computer model, most of the asteroid captured by Earth’s gravity will not revolve around her neat circles. They will move on complex curved paths. This is due to the fact that the mini-moon affects several attractive forces, so the difficult path is formed by joint efforts of gravity of the Earth, the Moon and the Sun. Mini-moon is under the influence of the earth, until one of the other two objects does not overpower the pull of the planet, and then the Sun regains control of the trajectory of the object. Although usually mini-moon revolves around our planet for about 9 months, some of them may remain in Earth orbit for decades.
"This was one of the largest and longest computations in my practice," - said Vaubayllion. "If you tried to do it on your home computer, it would take about six years."
In 2006, scientists at Arizona State University have found a car the size of a mini-moon. This object that has the prosaic name 2006 RH120, was in Earth orbit less than a year after its opening, and then returned to the rotation around the sun.
"Mini-moon have an extraordinary scientific interest," - said Dzhedike. "One day, we can bring a mini-moon to the Earth, it will provide an opportunity to explore a sample of material that has remained virtually unchanged since the birth of our solar system more than 4.6 billion years ago."
The scientific article command, entitled "The population of natural Earth satellites," will be published in March in the journal Icarus.
For calculations the team used a French supercomputer Jade.