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The Giant Planets Migrated Between 60-100 Million Years After the Solar System Formed – Universe Today

Untangling what happened in our Solar System tens or hundreds of millions of years ago is challenging. Millions of objects of wildly different masses interacted for billions of years, seeking natural stability. But its history—including the migration of the giant planets—explains what we see today in our Solar System and maybe in other, distant solar systems.

New research shows that giant planet migration began shortly after the Solar System formed.

Planetary migration is a well-established idea. The Grand-Tack Hypothesis says that Jupiter formed at 3.5 AU, migrated inward to 1.5 AU, and then back out again to 5.2 AU, where it resides today. Saturn was involved, too. Migration can also explain the Hot Jupiters we see orbiting extremely close to their stars in other solar systems. They couldn’t have formed there, so they must have migrated there. Even rocky planets can migrate early in a solar system’s history.

New research in the journal Science establishes dates for giant planet migration in our Solar System. Its title is “Dating the Solar System’s giant planet orbital instability using enstatite meteorites.” The lead author is Dr. Chrysa Avdellidou from the University of Leicester’s School of Physics and Astronomy.

“The question is, when did it happen?” Dr. Avdellidou asked. “The orbits of these planets destabilised due to some dynamical processes and then took their final positions that we see today. Each timing has a different implication, and it has been a great matter of debate in the community.”

“What we have tried to do with this work is to not only do a pure dynamical study, but combine different types of studies, linking observations, dynamical simulations, and studies of meteorites.”

The meteorites in this study are enstatites or E-type asteroids. E-type asteroids have enstatite (MgSiO3) achondrite surfaces. Achondrite means they lack chondrules, grains of rock that were once molten before being accreted to their parent body. Specifically, this group of meteorites are the low-iron chondrites called ELs.

When giant planets move, everything else responds. Tiny asteroids are insignificant compared to Jupiter’s mass. Scientists think E-type asteroids were dispersed during the gas giants’ outward migration. They may even have been the impactors in the hypothetical Late Heavy Bombardment.

Artist concept of Earth during the Late Heavy Bombardment period. Scientists have wondered if E-type asteroids disturbed during giant planet migration could've been responsible for the Bombardment, but the authors of this research don't favour that explanation. Credit: NASA's Goddard Space Flight Center Conceptual Image Lab. — Artist concept of Earth during the Late Heavy Bombardment period. Scientists have wondered if E-type asteroids disturbed during giant planet migration could’ve been responsible for the Bombardment, but the authors of this research don’t favour that explanation. Credit: NASA’s Goddard Space Flight Center Conceptual Image Lab.

Enstatite achondrites that have struck Earth have similar compositions and isotope ratios as Earth. This signals that they formed in the same part of the protoplanetary disk around the young Sun. Previous research by Dr. Avdellidou and others has linked the meteorites to a population of fragments in the asteroid belt named Athor.

This work hinges on linking meteorites to parent asteroids and measuring the isotopic ratios.

“If a meteorite type can be linked to a specific parent asteroid, it provides insight into the asteroid’s composition, time of formation, temperature evolution, and original size,” the authors explain. When it comes to composition, isotopic abundances are particularly important. Different isotopes decay at different rates, so analyzing their ratio tells researchers when each meteorite closed, meaning when it became cool enough that there was no more significant diffusion of isotopes. “Therefore, thermochronometers in meteorites can constrain the epoch at which major collisional events disturbed the cooling curves of the parent asteroid,” the authors explain.

The team’s research shows that Athor is a part of a once much larger parent body that formed closer to the Sun. It also suffered from a collision that reduced its size out of the asteroid belt.

Athor found its way back when the giant planets migrated. Athor was at the mercy of all that shifting mass and underwent its own migration back into the asteroid belt. Analysis of the meteorites showed that this couldn’t have happened earlier than 60 million years ago. Other research into asteroids in Jupiter’s orbit showed it couldn’t have happened later than 100 million years ago. Since the Solar System formed about 4.56 billion years ago, the giant planet migration happened between 4.5 and 4.46 billion years ago.

This schematic from the research shows what the researchers think happened. Red circles are planetesimals (and their fragments) from the terrestrial planet region. The black solid curves roughly denote the boundary of the current asteroid inner main belt. Eccentricity increases from bottom to top.

A shows the formation and cooling of the EL parent planetesimal in the terrestrial planet region before 60 Myr after Solar System formation. In this period, the terrestrial planets began scattering planetesimals to orbits with high eccentricity and semimajor axes corresponding to the asteroid main belt. B shows that between 60 and 100 Myr, the EL planetesimal was destroyed by an impact in the terrestrial planet region. At least one fragment (the Athor family progenitor) was scattered by the terrestrial planets into the scattered disk, as in (A). Then the giant planet instability implanted it into the inner main belt by decreasing its eccentricity. C shows that a few tens of millions of years after the giant planet instability occurred, a giant impact between the planetary embryo Theia and proto-Earth formed the Moon. D shows that the Athor family progenitor experienced another impact event that formed the Athor family at ~1500 Myr. Image Credit: Avdellidou et al. 2024.

Another important event happened right around the same time. About 4.5 billion years ago, a protoplanet named Theia smashed into Earth, creating the Moon. Could it all be related?

“The formation of the Moon also occurred within the range that we determined for the giant planet instability,” the authors write in their research. “This might be a coincidence, or there might be a causal relationship between the two events.”

“It’s like you have a puzzle, you understand that something should have happened, and you try to put events in the correct order to make the picture that you see today,” Dr. Avdellidou said. “The novelty with the study is that we are not only doing pure dynamical simulations, or only experiments, or only telescopic observations.”

“There were once five inner planets in our Solar System and not four, so that could have implications for other things, like how we form habitable planets. Questions like, when exactly objects came delivering volatile and organics to our planet to Earth and Mars?”

Artist's impression of the impact that caused the formation of the Moon. Could that impact have been caused by giant planet migration? Credit: NASA/GSFC — Artist’s impression of the impact that caused the formation of the Moon. Could giant planet migration have caused that impact? Credit: NASA/GSFC

The Solar System’s history is a convoluted, beautiful puzzle that somehow led to us. Everything had to work out for life to arise on Earth, sustain itself, and evolve for so long. The epic migration of the gas giants must have played a role, and this research brings its role into focus.

Never mind habitability, complex life, and civilization, the migration may have allowed Earth to form in the first place.

“The timing is very important because our Solar System at the beginning was populated by a lot of planetesimals,” said study co-author Marco Delbo, Director of Research at France’s Nice Observatory. “And the instability clears them, so if that happens 10 million years after the beginning of the Solar System, you clear the planetesimals immediately, whereas if you do it after 60 million years you have more time to bring materials to Earth and Mars.”

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Hurungwe man kills another, dumps body in river – Chronicle

Bongani Ndlovu, Online Reporter A HONDA Fit hit a pedestrian, veered off the road and crashed into a tree, killing the pedestrian, driver, and one passenger on the spot, while injuring another. In a statement, National Police Spokesperson Assistant Commissioner Paul Nyathi said the fatal accident along Simon Mazorodze Road, Waterfalls, Harare. “A Honda fit […]

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Chinese mission set to blast off to far side of moon: What you need to know about NASA and China’s space race – Sky News

China’s Chang’e-6 robotic spacecraft is due to blast off on Friday, hoping to become the first mission to collect rock and soil samples from the far side of the moon.

It is the next step in a tense race between NASA and China to create bases on the moon, and from there, lift off to Mars.

Since the first Chang’e mission in 2007, named after the mythical Chinese moon goddess, Beijing has made leaps forward in its lunar exploration.

What is Chang’e 6 going to do?

The spacecraft is set to land on the northeastern side of the huge South Pole-Aitken Basin. It’s the oldest impact crater in the solar system.

There, it will collect samples to bring home to Earth so scientists can study what is on the moon’s far side for the first time. In 2019, the mission’s predecessor, Chang’e-4, became the first spacecraft to successfully land on the moon’s far side.

We only ever see one side of the moon because it takes the same amount of time to spin on its axis as it does to orbit Earth, around one month.

The side that faces away from Earth is pockmarked with lots of craters of different sizes and has a thicker, older crust, according to NASA.

Once Chang’e-6 has collected all its samples, it will attempt to lift off from the far side of the moon for the first time in history.

Chang’e-6’s mission will last for around 53 days and will collect about 2kg of material using a scoop and a drill, says NASA.

It is the first of three missions using unmanned spacecraft before China attempts to land a crew and build a base on the lunar south pole.

Four countries – the US, Russia, China and India – have landed spacecraft on the moon.

The big race to space

The far side of the moon is an increasingly popular destination. Last year, India celebrated as its Chandrayaan-3 became the first spacecraft to land on the lunar south pole.

NASA intends to make history by sending the first humans near the lunar south pole in 2026 with its Artemis mission, and eventually build a habitable base there.

China says it plans to get there in 2030, but NASA’s administrator Bill Nelson recently said he thinks they’re speeding up their plans.

“The latest date they’ve said they’re going to land is 2030 but that keeps moving up,” he told the House Committee on Appropriations in April.

“It is incumbent on us to get there first,” he said.

So why is everyone so desperate to reach a side of the moon we can’t even see?

Simply put, it’s about water.

Ever since India discovered there might be ice in the moon’s south pole craters in 2008, scientists have wanted to know if there is water up there.

If there is, missions to Mars become much more achievable, as does sustaining long-term bases on the moon.

But Earth’s politics are playing out in space.

NASA wants to beat China to the moon so urgently because it believes the country will lay claim to the moon’s water and could be developing ‘secret military capabilities’ in space.

“My concern would be if China got there first and said, ‘This is our territory, you stay out’,” said Mr Nelson.

Around 39 countries including the UK have signed NASA’s Artemis Accords, an agreement that requires space activity to be conducted for peaceful purposes and that countries stick to the 1967 Outer Space Treaty.

That treaty says outer space ‘shall be the province of all mankind’.

Although China previously signed the Outer Space Treaty, it hasn’t signed up to the Artemis Accords.

Beijing, however, says it remains committed to cooperation with all nations on building a “shared” future.

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Fatal crash claims three lives on Workers’ Day – Chronicle

In a statement, National Police Spokesperson Assistant Commissioner Paul Nyathi said the fatal accident along Simon Mazorodze Road, Waterfalls, Harare.

“A Honda fit vehicle with two passengers on board hit a pedestrian resulting in the vehicle veering off the road before hitting a tree. Subsequently, the pedestrian, driver and a passenger died on the spot whilst the other passenger sustained some injuries,” said Assistant Commissioner Nyathi.

He said Police have released the names of two of the three victims who were identified by their next of kin, while the other victim is yet to be identified.

“Gumisai Kandime (32), a male adult of Ushewekunze, Harare. Tapfumanei Chisango (36), a male adult of Ushewekunze, Harare. The other victim is yet to be identified by the next of kin. The bodies of the victims were taken to Sally Mugabe Hospital mortuary for post mortem whilst the injured victim is admitted at the same hospital,” said Assistant Commissioner Nyathi.

He said as police they reiterate that motorists should be cautious on the roads and observe all road rules and regulations to safeguard human lives.