Unusual version published astronomers from the American University of Arizona, in their opinion about 4 billion years ago, immediately after the completion of the formation of the Solar system, two penultimate planets - Uranus and Neptune have changed orbits. Their arguments they intend to publish in the next issue of the scientific journal Astrophysical Journal.

In Arizona say that based on the calculation of the density of matter, then the final part of the formation of the solar nebula, we can say that initially the Uranium was on the place of Neptune and Vice versa.

Solar nebula was a vast disk of gas and dust in the center of which is already shining young Sun, and the drive is already actively shaped the planet. One of the main characteristics of the disc is its density, or the so-called mass in the region, it is on the basis of this indicator can be more or less accurately determine how quickly formed in a particular region of the planet, and what are the chemical elements specific region contained.

Scientists point out that today it is very difficult to observe the distribution of density of matter in protoplanetary drives from other systems, as they are all located very close to our planet.

For 30 years of observations the majority of researchers for a reference point taken, such parameter as the Minimum mass of the Solar nebula. The idea of this option is rather simple: the minimum volume density is taken stone components, hydrogen and helium, so that the weight of these components corresponds to the mass of each planet in the system, and is distributed evenly throughout the orbit motion of this planet. Thus, for a Minimum mass, you can accept the possible mass of the Solar nebula. Practical observations show that in other emerging planetary systems this option is approximately equal to our own.

"Proceeding from this model, it is impossible to explain why some tiny planet, such as mercury, and other real giants, such as Jupiter. Given the size and structure of Jupiter could say that it was formed millions of years longer than the other planets, and on Uranus and Neptune or just left of material, or they were generally formed billions of years. But this is impossible, our Solar system is not that old," says astrophysicist from the University of Arizona Steve Dash.

There is one more model - Nitrianska model (from the name of the French city of nice). It is based on more complex settings and partially explains the formation of Jupiter, Saturn, Uranus and Neptune, as well as the Kuiper belt, located behind them.

However, all modern computer simulation was carried out based on existing scientific data about the Solar system and Nitriansky the model suggests that for example Neptune, originally was located almost on 50% closer to the Sun, and later due to the redistribution of masses of Uranus and Neptune have changed orbits.

However, experts say that to prove this reshuffle in practice is impossible, as she was about 4 billion years ago.

"Most likely, the real density of the solar nebula was quite different than it is today. It was much more. It is the high density and can explain the rapid and simultaneous formation of such different planets. However, along with this, higher density also speaks to the fact that initially the planet was located much closer to each other, and Uranus and Neptune were even almost satellites each other. This is partly confirmed by the structure of their structure - they are a pair of planets most similar to each other from across the Solar system," says Dash.

According to him, the formation of the planets was also significantly faster, not a billion years, as was previously thought, and about 10 million years. "It is very important for understanding the processes of formation, as Uranus and Neptune in total contain hydrogen more than on Earth, and monitoring of other protoplanetary drives show that large accumulation of these light gases in the free state are not more than 10 million years," he says.

"Based on data from the mass of the solar nebula is very precisely to assume that the first 650 million years of the Solar system, Neptune was actually closer to the Sun than Uranus. Now the opposite is true," said the Dash.