How did this rocky outpost of life we call ‘Earth’ form, what process is capable of turning space dust and rubble into this picturesque blue planet we call home. Science has a fairly good understanding of the beginning and end of the life-cycle of solar systems and their planets but the middle bit is still a huge mystery. How we go from a dusty cloud to what we on Earth a used to seeing, a working solar system that’s the question. A number of recent discoveries are helping us shape our understanding of this process, the formation of planets. Central to this new understanding is the information being collected by many radio telescopes and satellites. With these new modern tools we are seeing for the first time this process in action. Discoveries are also being made in unexpected places, theories are being expanded or replaced faster than ever.
One of the greatest mysteries and hardest to observe processes is the earliest stage of planet formation, how that initial clumping of dust occurs, starting the snow ball rolling. Discoveries often happen in funny and unexpected ways. This discovered was made by a mad scientists experimenting on the International Space Station – ISS -. Dr Don Pettit - NASA Astronaut - had become famous for his hands on experiments in zero gravity. Pettit filmed everyday things in zero gravity, with a desire to simply learn about this new set of rules, the laws of zero-gravity. Many of the experiments exhibited unexpected behaviour, pleasant surprises that are helping us define our understanding of space. This discovery almost went unnoticed until fellow NASA scientist Dr Stanley Love was watching some of Pettit’s video’s of plastic bags filled with salt. The salt inside the bag clumped almost instantly once Pettit stopped shaking it. The shaking caused the dust to bump into each other, building up a static charge which caused them to be attracted – electrostatic coalescence – once clumped together surface tension took over to hold it all together. Again Pettite has some interesting video to demonstrate this point, an interesting experiment with corn candy. Very cool video by the way. When particles bump around in space the impacts cause an exchange of electrons this along with a complete lack of ground to discharge static it just builds up, this coupled with the fact that static works very differently in space than it does on Earth may be the basis for a solution to this mysterious part of the plant formation process.
In a paper to be published in The Astrophysical Journal, Kamen Todoro and his team – Penn State University – used the Hubble telescope and Gemini satellites to study the formation of a new solar system around a brown dwarf star. 32 young brown dwarfs in the Taurus star-forming region were surveyed. A brown dwarf is a sun that hasn’t ignited usually because it’s just a little to small to build up the gravity to kick-start fusion reactions. So instead of firing up it stays a brown murky ball of gas. A solar system can still form around this brown star as normal and this is exactly what the scientists studied. To their surprise one fo the brown dwarfs already had a planet formed in the dusty disc around the unlit star. Scientists estimated that the planet had formed in under a million years, the time it has taken to form the brown dwarf. According to Dr Todorov and his team this suggests that the planet actually formed as part of the star itself and was separated off for some reason. They don’t believe the planet was formed by dust and rocks collecting over time as the standard formation theory suggests, its way to fast. Interesting from both perspectives in that they are suggesting other ways of forming planets are possible and/or alternatively dust and rocks can collect much quicker than current theories think possible.
During the last 5 years teams of scientists from around the world have been hunting for planets orbiting nearby suns. With 500 planets discovered so far many things are being learned. There have been many exceptional discoveries made that are difficult to explain with current theories. “With the tally of confirmed planets orbiting other stars now more than 500, planet hunters are heading for a golden age of discovery”, said Dr Geoffrey Marcy of Berkeley University. Planet formation theories generally predict most planets should have a roughly circular orbit around their sun but in reality though, only about one in three of the known exoplanets has a circular or near-circular orbit. Also discovered was the fact that “Orbital inclinations are all over the map,” according to Marcy. Most planets were expected to have a flat orbit that matches the spin direction of the sun. This didn’t turn out to be true with about 30% of planets having an odd orbit, either travelling backwards or orbiting perpendicular to the other planets obits, north south instead of left right. Also, according to most of the current models on planet formation Neptune sized planets should be rare. During the planet formation process their size should let the sun’s gravity take hold dragging them inwards to a fiery death. Turns out that they are the most common sized planets. It seems the more bits of information we gather the more we change the picture of how things got started.
The current tools of the trade for astrophysicists are already generating massive amounts of data for scientists to work with. With it they fine tune their models, correct theories. There is a next generation technology already on the horizon. The Square Kilometre Array – SKA – is expected to generate more bits per second – information – than the internet. The array will be based in Western Australia and consists of 3,000 dishes with a combined surface area over 1 square kilometre, all joined together via optic network and all pointed at the same part of the sky.
The current models and theories for planet formation are being stretched, pushed and pulled in order to cover many new discoveries made in recent years. This is where we came from. From space dust to orbiting green house this is the life-cycle of solar systems and planets, a big subject in every possible way. It is inevitable that it will take time to perfect our understanding of its processes and peculiarities. Key to this are all of the technologies and machines we use to be our eyes and our ears. From the voyager space craft to the Square Kilometre Array telescope observing these process in action is essential for us to learn. Until evidence can be found to prove a theory it’s proto-science the gap filler of the science world. The fact that two NASA scientists can stumble upon one piece of the puzzle while billions of dollars worth of satellites adds another piece, all adding to a single pool of knowledge shows that the evidence is more important than the circumstances. Knowledge is like that though, it doesn’t care who knows it or how it becomes known, just that it is known.
Buddha’s Brother out…