by Andy Lloyd
August 26, 2019

from AndyLloyd Website

Spanish version





Image Credit:

K. Suda & Y. Akimoto/Mabuchi Design Office,

courtesy of Astrobiology Center, Japan

A daring new theory about a massive collision in the early solar system is gaining traction in the scientific community.

Its reliance upon a hefty planetary collision runs against the general grain of thinking, because such events are usually considered to be only remotely possible, on a statistical level. ⁽¹⁾

Nonetheless, the evidence emerging from the spacecraft Juno's exploration of Jupiter indicates that something very significant disrupted the gas giant's core early on. ⁽²⁾

It transpires that Jupiter's dense core, crushingly compressed below it immense atmosphere, is not quite a neatly arranged as planet-forming models would suggest. Instead, the core seems to be more of a nebulous melange of starting materials and atmospheric materials.

Something appears to have disrupted it early on - an event which had lasting consequences across the lifespan of the solar system. Cast your mind back to the impact of Shoemaker-Levy comets, and the grazing blows that the fragmented comets caused across Jupiter's upper atmospheric layers.

In no time at all, the giant planet returned to its normal appearance, although the impacts caused substantial changes within.

To disrupt the core itself, the impact would have to impact the planet's core itself - a direct hit by a body massive enough to survive the deep penetration necessary through Jupiter's deep atmosphere.

Not only would the impactor need to hit the central bulls-eye, it would also need to remain intact through its descent.

A planet about 10 times Earth's mass would be sufficient to the task, computer modeling suggests: ⁽²⁾

"...the collision scenario became even more compelling after [Shang-Fei Liu Sun Yat-sen in Zhuhai, China] ran 3D computer models that showed how a collision would affect Jupiter's core.

 

Because it's dense, and it comes in with a lot of energy, the impactor would be like a bullet that goes through the atmosphere and hits the core head-on," [Rice astronomer and study co-author Andrea] Isella said.

 

"Before impact, you have a very dense core, surrounded by atmosphere. The head-on impact spreads things out, diluting the core." ⁽¹⁾

The internal disruption to Jupiter would take literally billions of years to overcome.

Even 4.5 billion years on, the giant planet is still in a pickle deep down, Juno's data suggests.

Given that there is evidence of other significant collisions within the solar system:

• Uranus being toppled onto its side

• the collision between Earth and 'Theia' that led to the creation of the Moon

• the bulge on the Martian surface suggestive of a very significant impact,

...it seems as though planetary collisions were the norm in the early solar system.

How can this be accounted for within theories of planetary and solar system evolution?

 

Were other factors at play, increasing the likelihood of planetary collisions in the early solar system?

Also, does this proposed event make Jupiter an unusual example of a gas giant?

The researchers involved in this work think that these kinds of catastrophic events may be more common than previously thought.

The immensity of these collision events may explain heat flares around young stars, where some of the starlight has been temporarily affected up by immense post-collisional debris fields orbiting the star. ⁽¹⁾

Other scientists may be skeptical of these claims (even though they are backed up by some strong sets of numbers), but this new hypothesis may prove to have good predictive powers.

More so, it illustrates the very chaotic nature of the early solar system, and the high potential for planetary collisions during that time.




References

1. Jade Boyd, Rice University - "Young Jupiter was smacked head-on by massive newborn planet" - 15^th August 2019
    

2. Shang-Fei Liu, et al. - "The formation of Jupiter’s diluted core by a giant impact" - Nature, 2019; 572 (7769): 355