Jupiter’s interior is full of remnants of baby planets that the gas giant has swallowed as it expands to become the hippopotamus we see today, scientists have found. The findings come from the first clear view of chemistry under the planet’s cloudy outer atmosphere.
Although it is the largest planet in the solar system, Jupiter has revealed very little about his inner work. Telescopes have captured thousands of images of rotating vortex clouds in the gas giant upper atmospherebut these Van Gogh-style storms also act as a barrier blocking our view of what is below.
“Jupiter was one of the first planets to form” in the first few million years when solar system was formed about 4.5 billion years ago, lead researcher Jamila Miguel, an astrophysicist at Leiden University in the Netherlands, told Live Science. However, we know almost nothing for sure about how it was formed, she added.
In the new study, researchers were finally able to peek past Jupiter’s darkening cloud cover using gravitational data collected from NASA’s Juno spacecraft. These data allowed the team to draw the rocky material in the core of the giant planet, which revealed a surprisingly large abundance of heavy elements. The chemical composition suggests that Jupiter swallowed baby planets or planetesimals to fuel its expansive growth.
Growing a gas giant
Today, Jupiter may be mostly a sphere of spinning gas, but it began its life by accumulating rocky material – just like any other planet in the solar system. Like on the planet gravity drawn into more and more rocks, the rock core became so dense that it began to attract large amounts of gas from long distances – mostly hydrogen and helium left over from the sunthe birth of – to form a huge atmosphere filled with gas.
There are two competing theories about how Jupiter managed to assemble its original rocky material. One theory is that Jupiter has accumulated billions of smaller cosmic rocks, which astronomers call pebbles (although these rocks are probably closer in size to rocks than actual rocks).
The opposite theory, supported by the findings of the new study, is that Jupiter’s nucleus was formed by the absorption of many planetesimals – large space rocks covering a few miles, which, if left undisturbed, could potentially act as seeds, of which the smaller rocky planets such as The Earth or March can develop.
Until now, however, it has not been possible to say definitively which of these theories is true. “Since we can’t directly observe how Jupiter formed, we need to put together the pieces of information we have today,” Miguel said. – And this is not an easy task.
Probing the planet
To try to resolve the debate, researchers had to build a picture of the interior of Jupiter. “Here on Earth, we use seismographs to study the interior of the planet using earthquakes,” Miguel said. But Jupiter has no surface on which to place such devices, and Jupiter’s core is unlikely to have much tectonic activity, she added.
Instead, the researchers built computer models of Jupiter’s interior by combining data collected primarily from Juno and some data from its predecessor. Galileo. The probes measure the planet’s gravitational field at various points around its orbit. The data show that the rock material accumulated by Jupiter has a high concentration of heavy elements that form dense solids and therefore have a stronger gravitational effect than the gaseous atmosphere. These data allowed the team to plot slight variations in the planet’s gravity, which helped them see where the rocky material was within the planet.
“Juno provided very accurate data on gravity, which helped us limit the distribution of material inside Jupiter,” Miguel said. “This is very unique data that we can only get with a spaceship orbiting the planet.”
The researcher’s models revealed that Jupiter has the equivalent of between 11 and 30 Earth masses of heavy elements (3% to 9% of Jupiter’s mass), which is much more than expected.
Pebbles against planetesimals
The new models point to Jupiter’s planetesimal origin, as the theory of stone accumulation cannot explain such a high concentration of heavy elements, Miguel said. If Jupiter had originally formed from rocks, the eventual beginning of the process of gas accumulation, once the planet is large enough, would immediately end the phase of rock accumulation. This is because the growing layer of gas would create a pressure barrier that stops extra pebbles from being pulled inside the planet, Miguel explained. This limited phase of rock accumulation is likely to give Jupiter a significantly reduced abundance of heavy metals or metallicity than the researchers estimated.
However, planetesimals could shine in the core of Jupiter even after the gas accumulation phase has begun; this is because the gravitational pull on the rocks would be greater than the pressure exerted by the gas. This simultaneous accumulation of rocky material and gas, proposed by planetary theory, is the only explanation for Jupiter’s high levels of heavy elements, the researchers said.
The study revealed another interesting finding: the interior of Jupiter does not mix well with its upper atmosphere, which contradicts what scientists had previously expected. The new model of Jupiter’s interior shows that the heavy elements that the planet has swallowed have remained largely close to its core and lower atmosphere. Researchers have suggested that convection has mixed Jupiter’s atmosphere so that the hotter gas near the planet’s core will rise into the outer atmosphere before it cools and falls back; if this were the case, the heavy elements would mix more evenly throughout the atmosphere.
However, some regions of Jupiter may have a small convection effect and more research is needed to determine exactly what is happening in the gas giant’s atmosphere, Miguel said.
Researchers’ findings could also change stories about the origins of other planets in the solar system. “Jupiter was the most influential planet in the formation of the solar system,” Miguel said. Its gravitational pull has helped shape the size and orbits of its space neighbors, and determining how it came about has important impact effects on other planets, she added. The findings also suggest a potential planetesimal origin for other gas giants in the solar system: Saturn, Uranium and Neptune.
Other gaseous worlds in other stellar systems may also have been formed by the ingestion of planetesimals rather than pebbles, which means that they may also have higher metallicity than their appearance suggests. That is why it is important when we discover these new worlds that are being sought with the help of NASA James Webb Telescopewe don’t judge them by their cloud cover, the researchers said.
The study was published online June 8 in the journal Astronomy and astrophysics (opens in a new tab).
Originally published in Live Science.