Jupiter Was Once Twice as Big With 50x Stronger Magnetism, Says New Study

Recent research has given evidence that Jupiter was twice its current size in the past. Researchers have pointed out that Jupiter could be double its size around 3.8 million years ago and could accommodate 2000 Earths at once. However, it is still the largest planet in the solar system. It also had a magnetic field 50 times stronger than now. 

Studying Jupiter's Small Moons

According to the study published on May 20, 2025, in Nature Astronomy, researchers unveiled that Jupiter was once twice its current size. This research was led by Professor Konstantin Batygin of the California Institute of Technology. Batygin's team focused on Jupiter's small inner moons, Thebe and Amalthea, instead of estimating how fast gas giants accumulate mass. These satellites move in orbit close to the planet on a little tilted path.

Jupiter Twice in its Size in the Past

The team analysed and revealed that the infant Jupiter had a radius double that of present and a volume that can occupy 2000 Earths, whereas at present, 1321 Earths can occupy Jupiter. This expansion means that the massive, gas-rich envelope later contracted with time. The strong magnetic power in the past years influenced the surrounding space and matter in different ways, thus it provides the dynamics of the early solar system.

Jupiter's Influence on the Solar System

The study didn't show how this giant member of the solar system shaped other planets, but highlighted that the gas giant played a significant role in the organisation of the solar system through its gravitational pull. Knowing this phase helps the researchers reshape the forces that defined our neighbourhood.

A Benchmark for Planetary Science

As per Batygin, these findings provide a valuable benchmark for further models of how the solar system formed. Jupiter showed a significant evolution after the protoplanetary gas cloud evaporation, which signalled a crucial turning point when the planets settled into their fixed orbits. This discovery can help scientists to know about the solar system evolution.