The end of the solar system could come much sooner than previously thought because of the way the Sun will lose mass in the final stages of its life. A new study shows that Jupiter, Saturn, Uranus and Neptune could be thrown out of their stable orbits as the star goes through a red giant phase and later turns into a white dwarf.
The Sun will run out of its main fuel in about 5 billion years and will expand into a red giant. In the process, it will become much brighter and hotter, making Earth uninhabitable. The planet will likely be engulfed by the expanding star or remain as a lifeless, superheated world.
About 8 billion years from now, the Sun is expected to shrink to a white dwarf — a dense stellar remnant about the size of Earth. It will have lost a significant portion of its original mass, and this change will weaken its gravitational influence on the planets.
Uneven mass loss changes the forecast
Previous calculations have generally assumed that the Sun would lose mass smoothly and evenly. In such a scenario, the outer planets could maintain their orbits for a period comparable to a quintillion years — a number with 18 zeros.
Konstantin Batygin, Jim Fuller, and Fred Adams consider a different scenario. According to them, the matter can be thrown out in separate portions, at different times and in different directions. This will create small but cumulative gravitational pushes that will change the orbits of the planets.
“The Sun, when it dies, does not simply expand the planetary system it has built — it shakes it up and, more often than previously thought, scatters it“, the authors of the study write, quoted by The Independent.
In 40% of models, chaos begins before the white dwarf
In about 40 percent of computer simulations, the orbits begin to intersect while the star is still a red giant. This means that some of the outer planets could be scattered or ejected before the Sun completes its transformation into a white dwarf.
Even in scenarios where the system survives this phase, the prediction remains short on a cosmic scale. About 90 percent of the modeled systems destabilize within 3 billion years of the white dwarf's formation. This changes the expected dynamical stability of the outer Solar System from about 10 to 18 years to approximately 1 billion years.
The conclusions relate to statistical models, not to an exact prediction of the motion of each planet. For humanity, however, this scenario has no practical significance: life on Earth would likely have disappeared billions of years earlier, when the Sun becomes a red giant.
Source: independent.co.uk