Spotlight

Jupiter is the most massive planet in our solar system, likely formed first, probably influenced the formation of all planets, and likely dictated the delivery of water to Earth. Even if our solar system is not typical of the many other planetary systems found thus far, we need to understand how Jupiter formed and evolved in order to understand what happened, including embryo formation, possible gravitational instabilities, satellite and disk formation, magnetic field origin, luminosity and atmospheric composition. 

The problem has three aspects: The formation process, the subsequent evolution and the system as we see it now. Not surprisingly, the first of these is the least well known, the second is partly known and the third is best known. That is why the current state of the Jupiter system is important even though it is furthest removed from origin. Juno, a spacecraft in orbit about Jupiter, tells us much about Jupiter now, including clues to the formation and evolution. 

I will talk about Juno’s discoveries, especially the “dilute” core, the magnetic field and the nature of the atmosphere. I will describe why some aspects of the post-formation evolution are imperfectly understood(because we do not fully understand convection) and why many aspects of the formation are still speculative (despite an explosion of data about exoplanet formation). I will finally offer some thoughts on the satellite system and whether this adds an important clue to origin.

About Prof. David J. Stevenson