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Blobrana


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Title: The Changing Perception of the Solar System
Author: D. Nesvorny, F. Roig

The solar system has changed dramatically since its birth, and so did our understanding of it. A considerable research effort has been invested in the past decade in an attempt to reconstruct the solar system history, including the earliest stages some 4.5 billion years ago. The results indicate how several processes, such as planetary migration and dynamical instabilities, acted to relax the orbital spacing of the outer planets, and provided the needed perturbation to explain the present planetary orbits that are not precisely circular and coplanar. Here we highlight this work and illustrate the key results in a computer simulation that unifies several recently developed theories. The emerging view represents another step away from the initial perception of the solar system as part of unchanging heavens.

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Blobrana


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Lucky Earth survived cosmic pinball

Rogue alien planets are forcing astronomers to rethink the birth of our Solar System. What's emerging is a tale of hellfire, chaos and planetary pinball - and it's a miracle our Earth survived.
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Blobrana


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Title: Is the Solar System Stable ?
Authors: Jacques Laskar

Since the formulation of the problem by Newton, and during three centuries, astronomers and mathematicians have sought to demonstrate the stability of the Solar System. Thanks to the numerical experiments of the last two decades, we know now that the motion of the planets in the Solar System is chaotic, which prohibits any accurate prediction of their trajectories beyond a few tens of millions of years. The recent simulations even show that planetary collisions or ejections are possible on a period of less than 5 billion years, before the end of the life of the Sun.

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Blobrana


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 Sun too sluggish to act as a cosmic Concorde

The sun is no cosmic Concorde. Our star is moving through a cloud of interstellar gas too slowly to create a "sonic boom" that would shield the solar system from some galactic cosmic rays. The finding could help determine whether the sun's previous passage through interstellar clouds could have led to mass extinctions.
As it orbits the centre of the Milky Way, the solar system passes through different clouds of gas and dust shed by supernovae. It is currently moving through what is known as the Local Cloud.
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