The mysteries of Jupiter's core persist despite scientific advancements.

Jupiter: The Colossal Ruler of Our Solar System. Weighing in at 318 times the mass of Earth, Jupiter is the largest planet in our Solar System. Its size and immense gravity dictate the Solar System's dynamics, compelling comets and deflecting asteroids. Despite its enormous significance, many scientists believed that they had uncovered all the fundamental facts about Jupiter's structure. However, recent data from Juno space probe and experiments conducted at the world's largest laser fusion labs have revealed a mystery lurking in the core of this colossal gas giant.

Science on the rocks

Exploring the Depths of Jupiter's Core: A Fascinating Scientific Endeavor

In high school Earth science classes, students are taught about the Solar System and its planets. This unit would have covered the layout of the planets, with the small, rocky terrestrial worlds, including Mercury, Venus, Earth, and Mars, located on the inner part of the system. On the other hand, the outer Solar System is where the giants reside, including the gas giants Jupiter and Saturn, as well as the ice giants Uranus and Neptune. The centre of these larger worlds is thought to be a rocky core. For Jupiter, a textbook might have shown an illustrated cutaway of the gas giant, depicting thick outer layers of hydrogen and helium enveloping a compact nugget of rocky material nestled deep below.

For decades, the belief in a rocky core was the accepted gospel of planetary science. However, the details surrounding Jupiter's core remained somewhat mysterious. Due to its size, the physics of its interior push our understanding of matter to its limits. The extreme pressures inside Jupiter can reach millions of times that of Earth's surface, while the core's temperature can soar to 36,000°F (~20,000°C).

The study of Jupiter's core requires scientists to use extreme instruments because of these extreme conditions. The Center for Matter at Atomic Pressures (CMAP), a research consortium based at the University of Rochester and funded by the National Science Foundation, employs the most powerful lasers in the world to compress material samples. The Laboratory for Laser Energetics in Rochester is the ideal location for this investigation as it houses one of the premier laser fusion facilities worldwide. This state-of-the-art facility is equipped with a 60-beam laser system, which scientists use to pound samples of hydrogen, helium, or rocky material to the same temperatures and pressures found in Jupiter's core using gravity alone.

The Juno spacecraft is the other instrument used to study Jupiter, and it has played a significant role in the current crisis surrounding the understanding of Jupiter's core. Juno is currently orbiting the gas giant, diving in so close that it can capture images of Jupiter's cloud tops. By tracking the gravitational signature created by Jupiter's internal distribution of matter, scientists can determine the motion of Juno's orbit and trace the mystery surrounding Jupiter's core.

Jupiter’s equation of state

Juno Data Reveals Surprising Insights into Jupiter's Internal Structure. Recent data from the Juno probe has provided scientists with a wealth of new information about the internal structure of Jupiter, revealing that longstanding models are not entirely accurate. Gravity measurements taken by the probe have disproved the existence of Jupiter's great rocky core, which has been a central feature of traditional models.

Creating new models that accurately reflect the data is a challenging task, as the laws of physics dictate how a planet's layers are organized. The equation of state plays a crucial role in this process, determining the density of materials at different depths. However, this equation is influenced by factors such as the mixture of elements and physical properties of each layer.

To build more accurate models, scientists are turning to laser experiments, which have helped to establish the equation of state for Jupiter. By better understanding the physics involved, researchers can develop more precise models of the gas giant's structure.

The core of the issue

Revisiting Jupiter's Core: The Findings of CMAP Member Burkard Militzer. Recent studies led by Burkard Militzer, a CMAP member, have challenged the longstanding idea of a compact rocky core in Jupiter. By exploring various internal structure configurations using computer models, Militzer and his team have discovered a dilute core that extends rocky material only 63% of the way out to the surface. This contradicts the old models, suggesting that a core enclosing almost two-thirds of a planet's radius is not a core at all. Further, the team found that only 18% of the material deep within the planet was rocky. These findings challenge our current understanding of giant planet formation and evolution.

However, the results require further confirmation, and additional modelling and laser experiments will be necessary to evaluate the validity of the new models. If the findings hold, Juno's work will have made a significant contribution by exposing the limitations of our previous understanding of Jupiter. While overturning old concepts can be challenging, it is also an exciting opportunity for scientific discovery.