The Evolution of Planets

We are bounded in a nutshell of Infinite Space: Week 9: Reading #7: The Evolution of Planets

One of the most interesting components of astronomy is the study of planetary systems and the means by which these develop over the span of eons. Contemporaneously, we have the opportunity to probe distant stars in search of planetary bodies and how these form, seeing the same process which eventually led to our evolution on this rocky planet. Furthermore, there is a clear pattern which most planetary systems seem to follow in order to create rocky bodies, which we have seen in Chapter 23 of An Introduction to Modern Astrophysics by Carrol and Ostlie. The chapter features the way molecular clouds and other early accumulations of baryons began collapsing and retaining atoms from previous stellar events (metals and heavier materials necessary for the creation of rocky planets) eventually became star systems, with a proto-planetary disk surrounding the infant star. These stars would continue producing energy while the spinning materials continued to flatten as per conservation of angular momentum (due to the collisions of matter throughout the cloud making it flatten), eventually creating the disk from which planets emerge. The text also details how the metallicity of these disks is inextricably tied to the possibility of creating planets, determined by the surveys of exoplanets conducted yielding this clear relationship. From these disks came the first planets, come closer to the star than others, made of rock and silicates and others from gases with rocky cores, each unique yet all following the pattern discerned after years of studying our own solar system. However, the creation of planets was not a simple and continuous process, rather it involved violent changes and devastating events. In the early formation of systems, including our own, proto-planets would collide with one another, each’s gravity attracting the other till the largest game of billiards ended with a massive collision. This is the case of the Earth and the Moon, proto-planets which collided early on and remained bound to each other ever since.  

The development of our solar system is probably the closest celestial-scale event which led to us, and as such it offers some of the greatest insights into how we came to be on this not too warm nor too cold planet. From learning of comets and their delivery of ices to the early planets, to the way gas giants like Jupiter protect inner planets from larger objects by changing their course with their immense gravitational pull, the way the solar system, ours especially, has developed in a unique way to arrive at the evolution of life is a source of continual amazement and further investigation. To learn if this happens elsewhere, if there are other corners of the galaxy and beyond which have led to such a delicate, yet resilient and unyielding, system, we continue to build telescopes to search beyond what our eyes can perceive, including the Kepler space telescope and other missions on their way. One thing is certain: understanding how we got here will be a never-ending pursuit, and we wouldn’t want it any other way. 

References: 

Carroll, B. W., & Ostlie, D. A. (2007). The Early Universe. In B. W. Carroll, & D. A. Ostlie, An Introduction to Modern Astrophysics. San Francisco: Pearson: Addison Wesley.

 http://www.daviddarling.info/images/protoplanetary_disk.jpg