A radical new theory that planets are born within a massive veil of gas may help explain how recently discovered extrasolar planets developed their stunning diversity of sizes and locations.
In the theory, planets are born under wraps, hidden at the centers of giant gas clouds far from their parent stars. A star’s gravity then reels in the planetary cloud, stripping away some or all of the gas to reveal the planet inside.
Depending on how much of the gas is removed in the process, the unveiled planet would resemble a gas giant like Jupiter, a solid core with a layer of gas like Neptune or a solid body like Earth. Sergei Nayakshin of the University of Leicester in England describes the process in an upcoming Monthly Notices of the Royal Astronomical Society as well as in several papers posted online at arXiv.org.
Such a beginning might explain the abundance of small-to-middling extrasolar planets — including many Neptune-sized planets — recently spotted by NASA’s Kepler spacecraft orbiting within roasting distance of their stars (SN: 2/26/11, p. 18). Standard planet-formation models are facing unprecedented challenges because they can’t easily account for the many types of extrasolar planets described since 1995, notes theorist Aaron Boley of the University of Florida in Gainesville. “At the end of the day, we need to explain this diversity of planetary systems,” he says.
Nayakshin’s theory, along with a similar one by Boley and his collaborators, borrows ideas from two more traditional models. In a scenario known as core accretion, bits of solid particles coalesce within the disk of gas and dust surrounding a young star and form a solid core that resembles Mercury or Earth. The core may then snare enough gas to form a Jupiter. In the other model, known as gravitational instability, gas within the planet-forming disk suddenly fragments to form a giant blob, forming a Jupiter in one fell swoop.
Please click HERE to access the entire article, including a short video called "Planetary Swirl," which appears to visually describe this process of planet-building that we read about in The Urantia Book
As always, we are so heartened when we hear of scientific discovery and new theories that corroborate Urantia Book revelation regarding astronomy and cosmology:
41:10.1 Some of the variable stars, in or near the state of maximum pulsation, are in process of giving origin to subsidiary systems, many of which will eventually be much like your own sun and its revolving planets. Your sun was in just such a state of mighty pulsation when the massive Angona system swung into near approach, and the outer surface of the sun began to erupt veritable streams—continuous sheets—of matter. This kept up with ever-increasing violence until nearest apposition, when the limits of solar cohesion were reached and a vast pinnacle of matter, the ancestor of the solar system, was disgorged. In similar circumstances the closest approach of the attracting body sometimes draws off whole planets, even a quarter or third of a sun. These major extrusions form certain peculiar cloud-bound types of worlds, spheres much like Jupiter and Saturn.
57:2.1 All evolutionary material creations are born of circular and gaseous nebulae, and all such primary nebulae are circular throughout the early part of their gaseous existence. As they grow older, they usually become spiral, and when their function of sun formation has run its course, they often terminate as clusters of stars or as enormous suns surrounded by a varying number of planets, satellites, and smaller groups of matter in many ways resembling your own diminutive solar system.
57:5.10 Jupiter and Saturn, being derived from the very center of the enormous column of superheated solar gases, contained so much highly heated sun material that they shone with a brilliant light and emitted enormous volumes of heat; they were in reality secondary suns for a short period after their formation as separate space bodies. These two largest of the solar system planets have remained largely gaseous to this day, not even yet having cooled off to the point of complete condensation or solidification.
Also see "The Origin of Urantia"