As an expert in the field of planetary science, I can provide you with an in-depth analysis of the question regarding the oldest planet in our solar system. The solar system is believed to have formed around 4.6 billion years ago from the gravitational collapse of a giant molecular cloud. The process of planet formation is complex and involves several stages, including the accretion of solid particles, the formation of planetesimals, and the eventual coalescence of these bodies into planets.

The study you mentioned, which suggests that Jupiter's core had grown to be 20 times more massive than Earth just 1 million years after the Sun formed, is indeed a significant finding. This rapid growth indicates that Jupiter, a gas giant, may have formed earlier than previously thought. The core accretion model of planet formation posits that gas giants like Jupiter begin their formation with a solid core that grows by accreting surrounding material, and once a critical mass is reached, the core can attract a massive envelope of gas.

However, determining the exact age of a planet is not straightforward. Planetary ages are typically inferred from the age of the solar system and the relative ages of different planetary features. Radiometric dating of meteorites, which are believed to be some of the oldest objects in the solar system, provides a good estimate for the age of the solar system. These meteorites are thought to have formed during the early stages of the solar system's history, and their radiometric ages are consistent with the formation of the solar system around 4.6 billion years ago.

It's important to note that the age of a planet's core does not necessarily reflect the age of the planet itself. Planetary bodies are dynamic and undergo various processes that can alter their surfaces and interiors over time. For example, the Moon is believed to be about 4.5 billion years old, but its surface has been resurfaced multiple times by impacts, which can make it difficult to determine its exact age.

In the case of Jupiter, the gas giant's rapid formation suggests that it may be one of the earliest planets to form in the solar system. However, the exact timing of its formation is still a subject of ongoing research and debate among scientists. Other gas giants like Saturn and ice giants like Uranus and Neptune also formed relatively early in the solar system's history, but the precise order of their formation remains uncertain.

In summary, while Jupiter's early formation is suggested by the growth of its core, the title of the oldest planet in the solar system is not definitively awarded to any single planet. The formation of the planets was a dynamic process that occurred over millions of years, and the exact ages of the planets are still being refined as new data and models are developed.

read more >>

Ancient Jupiter: Gas Giant Is Solar System's Oldest Planet. View of Jupiter's south pole created using data from NASA's Juno spacecraft. The gas giant's core had already grown to be 20 times more massive than Earth just 1 million years after the sun formed, a new study suggests.Jun 12, 2017read more >>