Planet formation theory

Planet formation theory Introduction Formation of the Solar System Accretion of solid bodies led to formation planetesimals protoplanets planets Planet formation is a much talked upon topic amongst scientists, although most agree with Viktor Safronovs planet formation theory. Safronov proposed the planetesimal hypothesis, which states, planets are created from dust particles which undergo collisions and stick together, eventually forming larger and larger bodies. The dust particles collide due to the gravitational forces exerted on upon the surrounding gasses by the protoplanetary disk. The protoplanetary disk is a rotating disk of matter which includes gas and dust, which surrounds newly formed stars.As the bodies increase in sizes to upwards of 1 kilometer, their own gravitational forces help them in supplementary growth into protoplanets. Another theory which tries to explain the formation of the universe was the gravitational collapse theory, which says planets form much like stars through the swift contraction of hydrogen clouds in the nebula. Although this theory provides a model of the creation of the universe, it does nt fit the available data, and cannot explain the creation of terrestrial-mass planets. 1 1 http://www.deepfly.org/TheNeighborhood/7c3-Evolution.html Terrestrial inner planets vs. Outer giant gaseous planets Our solar system consists of 8 planets, which orbit around the sun. The four inner planets are Mercury, Venus, Earth, and Mars. Theses planets are composed of heavier elements such as Iron, Silicon, Magnesium, Sulphur, and Nickel, as such they are all terrestrial planets. The four outer planets are Jupiter, Saturn, Uranus, and Neptune. They are composed of lighter elements, mostly consisting of Hydrogen and Helium. The differences between the outer gaseous planets and the inner terrestrial planets can all be explained by the theory of accretion and of the activity of the protoplanetary disc. Accretion is the process by which debris and dust are joint together through collisions due to gravitational forces within the protoplanetary disc. Findings show that gaseous components of begin to dispel soon after the star birth, and the nebula is fully depleted within just several million years. As such in many cases, accretion would take place at a greater rate than the depletion of gases, al lowing protoplanets of critical mass about 10 times that of Earth, to form within this time. Outer gas giants are formed within the ice line of the solar system where there is a high concentration of ice and gases allowing many collisions to place and as such create a planet of large critical mass. On the other hand, Terrestrial planets form much slower than gaseous planets, since they are composed in the ice line, a region which give little orbital space and mostly rocky and metallic materials. Their slow accretion rates are due to the fact that this region does not possess as much ice and gasses as the other regions. After the process of accretion, protoplanets of sizes of several hundred kilometres are formed, and these planets face many more collisions, eventually becoming Terrestrial planets. 1 1http://www.deepfly.org/TheNeighborhood/7c3-Evolution.html Formation of planetary rings Planetary rings are rings of dust, rocks, and other small particles orbiting around a planet in a flat circular motion, as seen in figure 1. These planetary rings are found in the four outer gaseous planets Jupiter, Saturn, Uranus, and Neptune. A prime example of this would be the ever famous rings of Saturn. The source of particles for these planetary rings can be traced back to the numerous collisions of Icy planetesimals which caused fragmentations and so bring forth many smaller pieces. Although the real mystery which plagues the minds of scientists, is how the material which make up these enormous rings were brought to their present position inside the gravitational radius of the planets. This process may have been different for every ring system. For instance, Jupiters rings are to be in a mature state, with balance between the loss of particles, and the production of new ones, supplied from the planets inner moons. On the other hand, scientists are divided over their beliefs o n how the rings of Saturn were formed. Some believe the rings are remnants of the protoplanetary process, whiles others believe the rings have just come into existence only several million years ago. 1 http://www.britannica.com/EBchecked/topic/553008/solar-system/242067/Formation-of-ring-systems Asteroid belt, between , Mars and Jupiter Asteroids are small irregularly shaped bodies of material composed of rocks and metals, which rotate the sun in a region between Mars and Jupiter. Asteroids are also known as Small Solar System Bodies (SSSBs), along with other irregular shaped materials such as comets. One theory suggests that asteroids are the remains of a larger protoplanet which faced a cataclysmic collision resulting in its numerous partitions, yet this theory fails to explain why there are exactly so many asteroids in the asteroid belt. Therefore scientists widely consider the following as the correct hypothesis on the creation of the asteroid belt. It is believed that asteroids are the remnants of protoplanetary matter formed by the protoplanetary disc, which can be seen by the immense number of asteroids in our solar system. Asteroids are leftover since they were within the immense gravitational radius of Jupiter, causing them to undergo destructive collisions, and even at times slinging them at a course beyon d the gravitational energies of our solar system. Therefore, no planetesimals could be formed and thus, the rocky matter remains continuously orbiting the sun.1 http://www.solstation.com/stars/asteroid.htm Formation of Earths moon We as humans need the moon. For it is the Moon`s orbit around the Earth that gives our planet a stable rotation, preventing polar shifts, which could lead to catastrophic results in global climate. Some scientists even believe the moon was a fundamental factor in the evolutionary cycle of life on earth. This is because the moon is of the main causes of Tides on Earth, and these very tides were a fundamental factor in the migration of amphibians into coastal regions, and eventually onto land. 2 Approximately 4.5 billion years ago, around the time of Earth`s formation, other protoplanetary bodies were also growing. At one point a protoplanetary body hit the Earth, sending massive amounts of debris into outer space, as seen in figure 2 (below). This debris started orbiting the Earth and eventually amassed into the moon. This theory is widely accepted since it is able to explain why the moon is not composed of an iron. The moon does not contain an iron core since, at the time of the coll ision the Earth had already depleted all of the Iron into its core, and the protoplanets iron core fused with the Earth`s core, thus only rocky matter rid of all iron was released into space. Secondly, the Earth and the moon share the same isotope composition, which can only be if the moon were formed from material from the Earth. Other theories which tried to explain the formation of the moon are the following. First, it was proposed that the Moon is a separate planetary body which formed around Earth, and went into its orbit, yet this theory failed to explain why the moon contains a core that lacks iron. Second, it was hypothesized that the moon formed elsewhere in the solar system at a place with little iron, and was gravitated into an orbit around earth, but this theory could not justify the fact that the moon`s oxygen isotope composition was the same as Earths. Third, it was proposed that the Earth had spun so fast that it spun off the moon, explaining the equivalent isotope co mposition and iron-less core, yet it failed when proper calculation were done which concluded that the moons present orbit could not take place if this hypothesis were to be correct. 2 http://www.space.com/scienceastronomy/moon_mechanics_0303018.html 1http://www.psi.edu/projects/moon/moon.html Unusual rotation of Uranus http://www.solarviews.com/eng/uranus.htm http://science.nationalgeographic.com/science/space/solar-system/uranus-article.html Concluding Paragraph

Of Mice And Men: A Critical Look At Curley?s Wife :: essays research papers

‘Of Mice and Men’, a novel by John Steinbeck, tells a story of friendship, loneliness and aspirations. Two itinerants named George and Lennie go to work on a farm as labourers in a place named Soledad. The story then ends when George takes Lennie’s life. Almost everyone on the farm is lonely and the person that represents this the most is Curley’s (the boss’s son) wife, one of the most pivotal characters in the book. When Lennie and George arrive on the farm and are shown their quarters Curley’s wife, on one of her ‘looking for Curley’ routines, sees them both and immediately starts flirting with them. George gets angry when Lennie takes a shine to her and tell him to stay away and calls her a ‘bitch’ and a ‘rat-trap’ This view is also held by many of the workers on the farm. Curley instantly takes a dislike to Lennie when he firsts meets him just because he his much considerably larger that himself. Thi s attitude towards Lennie results in him getting into a fight with him but he loses when Lennie crushes his hand with his own fist. Curley’s wife knows Lennie did this even though Curly was told to say he had caught his hand in a machine. Curley’s wife pursuit of company leads her to seek solace with Lennie. She pours out her pent up frustration of her unrealised dreams and ambitions. When she realises Lennie isn’t taking much interest she lets him feel her hair. Lennie being Lennie strokes harder and harder even though Curley’s wife begs him to stop. As she struggled to get out of his grasp he accidentally broke her neck. Lennie then ran off to his hiding place where he was told to go if he ever did a ‘bad thing.’ When Curley discovers his wife’s body he runs after Lennie with a mob including George. This leads to George pulling a trigger on Lennie. I feel Curley’s wife is the most despairing and lonely character in the book. She has no friends, no future, no respect; she doesn’t even deserve a name. I really feel sorry for her, all she wants is someone to talk to, to converse with but in her mind the only way she can do this is by flaunting herself to the men just to get noticed. This leads her to be perceived as a ‘floosy’ by the men.

Favorite Holidays Essay

1. One of my favorite Holidays is 4th of July. A few years ago my dad and I went to Washington to pick out some illegal fireworks. So we went to the Black Cat firework store . I got some mortars and roman candles and all the fun fireworks you could think of. So the day before 4th of July we were lighting off a few roman candles and all of a sudden a under cover police car pulled into our driveway and the police officer inside the car said â€Å"are you lighting off illegal fireworks?† because he saw me with the roman candles, and my dad said â€Å"yes† so the police officer confiscated all the fireworks we had bought and were fined a thousand dollars. We did get our ticket reduced down to $250 because we attended a fire works class. This definitely opened my eyes to the danger of fire works. From that day forward, I’ve learned not to do anything your not supposed to do, like buy illegal fireworks. 2. My sister graduated last year and moved to Los Angeles to pursue her passion. She grew up training in dance and singing. We have a close family and we support her all the way. My family and I traveled to see her this summer. She sang originals song and danced with her back up dancers for the music label industry. Very important people were their to see her. She did fantastic and is signing with a major record label. She will be releasing her single by the end of this year and her album in Januarary of 2014. This was a big eye opener to me to know that working hard and pursuing your dreams can really come true. 3. A couple years ago my grandmother passed away. She was very sick the last few days she was alive and my family and I knew she only had a few more days before she was to pass away. I helped her all that I could and so did my parents. She was a great grandmother and nobody could replace her, she was my dads mother, she was the best grandmother anybody could ask for. I remember the game we use to play when she would babysit me, it was called hide the thimble. She had a thumb thimble for sewing, and we use to hide it all over her house kind of like hide and seek, she also used to make the best brownies I have ever eaten. But from that day on I have always learned one thing, you never know how much you miss someone until there gone.

Italian Verbs Conjugated Trascorrere