* Formation was a gradual process: The planets formed from a disk of gas and dust around the young Sun. This process took millions of years, with different parts of the disk coming together at different rates.
* Early Solar System was chaotic: The early solar system was a very turbulent place, with collisions and gravitational interactions constantly reshaping the planets.
However, here's what we do know:
* Inner planets formed faster: The inner planets (Mercury, Venus, Earth, Mars) formed faster than the outer planets (Jupiter, Saturn, Uranus, Neptune) because they were closer to the Sun and had less material to accumulate.
* Jupiter's core may be very old: Some scientists believe that Jupiter's core may have formed very early, perhaps within a few million years after the Sun itself formed. However, Jupiter's gaseous atmosphere continued to build up for millions of years after that.
In short, while we can't definitively say which planet formed first, the inner planets likely formed faster than the outer planets, and Jupiter's core may be among the oldest structures in our solar system.
