Jupiter and Saturn have protected life on Earth for hundreds of millions of years by shielding us from comets.
Many large comets hurtling towards Earth all the way from the edge of the Solar System have been batted away by the two gas giants, preserving life as we know it.
The guardian planets effectively act as the planet’s bouncers, research has shown.
Most scientists agree that a catastrophic asteroid collision 65 million years ago wiped out the dinosaurs.
Astronomers know that Jupiter and Saturn’s gravitational fields can eject comets into interstellar space, or draw them in so that they crash into the giant planets.
The new study suggests we may owe the guardian planets more than we think.
One minor extinction event 40 million years ago was probably caused by an unusually intense burst of comets that slipped past Jupiter and Saturn.
It was clear the Earth had benefited from Jupiter and Saturn standing guard like giant ‘catchers mitts’, deflecting or absorbing comets that might otherwise strike the Earth.
Guardian planets Jupiter and Saturn shield the Earth from catastrophic comet collisions
By DAILY MAIL REPORTER
http://www.dailymail.co.uk/sciencetech/article-1203405/Guardian-planets-Jupiter-Saturn-shield-Earth-catastrophic-comet-collisions.html
Jupiter and Saturn have protected life on Earth for hundreds of millions of years by shielding us from comets.
Many large comets hurtling towards Earth all the way from the edge of the Solar System have been batted away by the two gas giants, preserving life as we know it.
The guardian planets effectively act as the planet’s bouncers, research has shown.
Most scientists agree that a catastrophic asteroid collision 65 million years ago wiped out the dinosaurs.
But the new research suggests few, if any, mass extinctions have been caused by the ‘long-period’ comets that take from 200 to tens of millions of years to orbit the Sun.
Previously it was thought that long-period comets, originating from a mysterious region called the ‘Oort Cloud’, occasionally destroyed life on Earth.
Astronomers know that Jupiter and Saturn’s gravitational fields can eject comets into interstellar space, or draw them in so that they crash into the giant planets.
Last week a huge scar appeared on Jupiter’s surface, thought to be caused by a comet impact.
The new study suggests we may owe the guardian planets more than we think.
Computer models simulating comet evolution in the Solar System for 1.2 billion years showed that the Oort Cloud was a bigger danger than previously realised.
Even outside active periods of comet showers, triggered by the close passage of a star, the inner Oort Cloud was a major source of threatening long-period comets.
The Cloud is a region of icy dust and debris left over from the birth of the Solar System. It starts from a point about 93 billion miles from the Sun and stretches for around three light years.
Scientists believe the Oort Cloud could contain billions of comets, most of them small and hidden.
About 3,200 long-period comets are known, one of the most famous being Hale-Bopp which was visible to even the naked eye during 1996 and 1997. Halley’s Comet, which reappears about every 75 years, is a ‘short-period’ comet from a different part of the Solar System called the Kuiper Belt.
The computer simulations showed that no more than two or three comets from the Oort Cloud could have struck the Earth during what is believed to have been the most powerful comet shower of the last 500 million years.
One minor extinction event 40 million years ago was probably caused by an unusually intense burst of comets that slipped past Jupiter and Saturn.
Astronomer Nathan Kaib, from the University of Washington, who led the study, said: ‘That tells you that the most powerful comet showers caused minor extinctions and other showers should have been less severe, so comet showers are probably not likely causes of mass extinction events.’
It was clear the Earth had benefited from Jupiter and Saturn standing guard like giant ‘catchers mitts’, deflecting or absorbing comets that might otherwise strike the Earth.
‘We show that Jupiter and Saturn are not perfect, and some of the comets from the inner Oort Cloud are able to break through, but most don’t,’ said Mr Kaib.
The research appears today in the online edition of the journal Science.
What’s So Special about Jupiter and Saturn?
By Dr. Hugh Ross
http://www.reasons.org/articles/what%E2%80%99s-so-special-about-jupiter-and-saturn
It was 1980. I was scheduled to speak in what was then an extremely violent part of Soweto, South Africa. Five burly men joined me in a car ride to the event; I sat in the middle of the back seat and was instructed by my companions to “keep my head down.” The reasoning was that if any bullets or other projectiles penetrated the car my companions would absorb the damage and thereby keep me safe.
Jupiter and Saturn offer the same kind of protection for Earth. Because Jupiter and Saturn are so large and massive compared to Earth (see figures 1 and 2), they shield Earth from would-be attackers (in this case, asteroid and comet collisions) by scattering incoming objects gravitationally or by absorbing collisions themselves.
Astronomers now realize it is not just the size and mass of both Jupiter and Saturn that work together to protect Earth—it is also the dimensions and characteristics of these gas giants’ respective orbits. If these two planets orbited any closer to Earth or manifested orbits any more eccentric (elliptical), their gravity would so disturb Earth’s own orbit so as to make it unfit for the support of advanced life. On the other hand, if they were more distant or their masses any smaller, they would not protect Earth adequately.
Two Chinese astronomers at Nanjing University, Hui Zhang and Ji-Lin Zhou, set out to model Jupiter-Saturn configurations. Specifically, they investigated the orbital evolution of two gas giant planets with masses analogous to those of Jupiter and Saturn in a gaseous disk surrounding its host star.
In their first paper, Zhang and Zhou considered the case where the Jupiter analogue orbited its host star interior to the orbit of the Saturn analogue,1 just like Jupiter does in our solar system. They found that tidal perturbations of the Jupiter analogue generated either an inward or an outward runaway migration of the Saturn analogue. That is, either the Saturn analogue was sent hurtling in toward the host star or it was flung out into the far outer reaches of the planetary system.
The only exceptions to these runaway migration scenarios were those where the Saturn analogue was trapped into either a 2:1 or 3:2 mean motion resonance. These resonances are situations where the Jupiter analogue completes either two orbits for every single orbit of the Saturn analogue or three orbits for every two orbits of the Saturn analogue. Both circumstances would disrupt the orbits of smaller planets existing in the same planetary system.
In their second paper, Zhang and Zhou analyzed the reverse configuration, where the Saturn analogue orbited its host star interior to the Jupiter analogue.2 They found that where the initial separation of the two planets is relatively large, the two planets undergo divergent migration. Depending on the properties of the gaseous disk, (1) the Jupiter analogue migrates outward while the Saturn analogue rapidly migrates inward; or (2) both planets migrate inward, with the Saturn analogue migrating at a much faster rate. Either way, the most likely outcome of the Saturn analogue is that it ends up with a close-in, high-eccentricity orbit of the host star.
Zhang and Zhou’s second paper goes a long way toward explaining why so many of the 490 known extrasolar planets are “hot-Jupiters” or “hot-Saturns” with high-eccentricity orbits. Their two papers also help explain why astronomers so far have failed to find a planet that matches both the physical and orbital characteristics of either Jupiter or Saturn.
How is it, then, that Jupiter and Saturn attained all the characteristics that permit the existence of advanced life on Earth? As I reported in our booklet 10 Breakthroughs of 2009, thanks to a just-right combination of supernovae exploding at just-right locations and times relative to the emerging solar system, the primordial solar system was bombarded with aluminum-26 isotopes.3 These isotopes so irradiated the early solar system as to drive off the gas disk and deplete the emerging planets of much of their methane, water, carbon monoxide, and carbon dioxide.4 In combination with the existence of two fine-tuned smaller gas giant planets (Uranus and Neptune) and three fine-tuned comet/asteroid belts (main belt, Kuiper belt, and Oort cloud), this fine-tuned gas depletion paved the way for the formation of the Sun’s planetary system such that one of those planets can sustain advanced life.
By itself, Zhang and Zhou’s analysis did not solve the problem of how Jupiter and Saturn ended up with the just-right features to permit the existence of advanced life on Earth. Their research, however, did add to the weight of evidence for the rare-Earth and rare-solar system doctrines. These doctrines state that planets the size and mass of Earth may prove abundant, but planets with just-right characteristics, physical and chemical composition, and planetary partners to enable the support of advanced life will prove either rare or nonexistent. Such doctrines are consistent with the Bible’s message that God supernaturally designed Earth, its planetary partners, and its life for the specific benefit of human beings.