A new theory explains Jupiter’s perplexing origin
A new computer model solves a pair of Jovian riddles.
- Astronomers have wondered how a gas giant like Jupiter could sit in the middle of our solar system's planets.
- Also unexplained has been the pair of asteroid clusters in front of and behind Jupiter in its orbit.
- Putting the two questions together revealed the answer to both.
Jupiter's long been a puzzler to astronomers. Planet formation theory holds that a gas giant forms far away from its star then moves inward over time until it's in a tight orbit around the sun. Jupiter, though, sits right in the middle of our solar system's planets, between Mars and Saturn. And that's not all that's odd: There's an unexpectedly asymmetrical pair of asteroid clusters — known as the Trojan asteroids — preceding and trailing Jupiter in its orbit. The group in front is 50% larger than the one in back. The most widely accepted idea was that Jupiter formed near the Sun and moved outwards.
That's now been turned on its head by a team of scientists from Lund University who ran a series of models to try to identify a plausible origin story for Jupiter. They discovered that the planet and its clusters would be where they are under only one scenario: Jupiter forming way out near Uranus — as gas giants are supposed to do, after all — and moving slowly toward the Sun, attracting and accreting the asteroids that now form its core, with the leftovers trailing behind. Lead author Simona Pirani says, "This is the first time we have proof that Jupiter was formed a long way from the Sun and then migrated to its current orbit." Including the mystery of the asymmetrical Trojans in the simulations was the key.
Jupiter, right in the middle of everything.
The model that lands Jupiter where it is today, along with its thousand of Trojans, begins four times further away from the Sun than Jupiter currently orbits, just inside of Uranus' orbit. Jupiter first took form about 4.5 billion years back as an icy planetary seedling, an ice asteroid, no bigger than Earth. Somewhere between two and three million years later, the future giant began spiraling slowly inward toward the Sun, pulled by gases circulating throughout the solar system. It took about 700,000 years to get where it is now. Along the way, before it developed its gaseous atmosphere and massive size, Jupiter's gravity pulled the Trojans in — the researchers expect Jupiter's core to be composed of materials similar to the Trojans. They're believed to be rich with dark carbon compounds, and likely rich in water and other volatile materials beneath an outer layer of dust.
Lucy in the sky with Trojans
(Astronomical Institute of CAS/Petr Scheirich)
Trojan clusters held in place by the Sun and Jupiter
In October 2021, NASA plans to launch its Lucy mission to study the Trojans. It's believed that they're very old time capsules from the universe of four billion years ago. The craft will study seven of them: one from the solar system's main asteroid belt, and the remaining six from the clusters leading and following Jupiter in its orbit.
Those two Trojan groups are held in place at stable LaGrange points by the combined gravitation pull of the Sun and Jupiter acting together as a single centrifugal force acting upon them.
NASA has high hopes for the mission as chance to get a closeup look at the type of materials from which our planetary bodies formed.
Meanwhile, Jupiter's seeming a little bit less mysterious now, at least in terms of its origin. It may also be that ice giants Uranus and Neptune, as well as Saturn, have a similar history.
Why are so many objects in space shaped like discs?
E-cigarettes may be safer than traditional cigarettes, but they come with their own risks.
- A new study used an MRI machine to examine how vaping e-cigarettes affects users' cardiovascular systems immediately after inhalation.
- The results showed that vaping causes impaired circulation, stiffer arteries and less oxygen in their blood.
- The new study adds to a growing body of research showing that e-cigarettes – while likely safer than traditional cigarettes – are far from harmless.
French newspapers report that the trial hasn't lived up to expectations.
- The French government initially invested in a rural solar roadway in 2016.
- French newspapers report that the trial hasn't lived up to expectations.
- Solar panel "paved" roadways are proving to be inefficient and too expensive.
The Lumina Foundation lays out steps for increasing access to quality post-secondary education credentials.
- America's post-high school education landscape was not created with the modern student in mind. Today, clear and flexible pathways are necessary to help individuals access education that can help them lead a better life.
- Elizabeth Garlow explains the Lumina Foundation's strategy to create a post-secondary education system that works for all students. This includes credential recognition, affordability, a more competency-based system, and quality assurance.
- Systemic historic factors have contributed to inequality in the education system. Lumina aims to close those gaps in educational attainment.
- In 2019, Lumina Foundation and Big Think teamed up to create the Lumina Prize, a search to find the most innovative and scalable ideas in post-secondary education. You can see the winners of the Lumina Prize here – congratulations to PeerForward and Greater Commons!