© NASA / JPL-Caltech / Space Science Institute
New research has found that Saturn may play a crucial role in shielding the Earth from asteroids, challenging the theory that Jupiter acts as our sole protector by steering scuttling planetoids off-course and into the far reaches of the galaxy.

Experiments conducted by planetary physicist Kevin Grazier of NASA's Jet Propulsion Laboratory suggest Saturn plays an equally important role in shielding Earth from harmful asteroids.

Grazier's findings also suggest that Jupiter, previously considered to be the Earth's only shield, could have played a part in the formation of all life on our blue planet by aiding the delivery of the building blocks for organic existence.

The study, published in the journal Astrobiology, found that Jupiter's immense gravitational field slows comets and asteroids entering the solar system, resulting in a much higher chance that life-generating material from these objects will accumulate on Earth.

"A comparison of multiple runs with different planetary configurations revealed that Jupiter was responsible for the vast majority of the encounters which "kicked" outer planet material into the terrestrial planet region, and that Saturn assisted in the process far more than has previously been acknowledged," the study found.

Using computer simulations, the study shows that planetoids are ejected into the depths of the solar system and beyond by both planets, but that many were destroyed having passed through the gas giants and entered the inner solar system.

"The simulations predict that Jupiter's capacity to shield or intercept Earth-bound comets originating in the outer Solar System is poor, and that the importance of jovian planets on the formation of life is not that they act as shields, but rather that they deliver life-enabling volatiles to the terrestrial planets."