-Melissa Greenberg, Arielle Hoffman, Zachary Feldmann, Ryan Pozin, Elizabeth Weeks, Christopher Pesota, & Sara Pilcher
Formation Overview All explanations as to how the solar system was formed are only theories and may change/evolve as scientists and astronomers continue to learn more The formation of the solar system that we know today occurred 4.6 billion years ago when a giant dense cloud of gas and dust known as a molecular cloud collapsed upon itself. There was most likely a disturbance caused by a supernova (an exploding star), and the resulting waves compressed the cloud causing gravity to pull the gas and dust together, thus forming a solar nebula. This caused the entire cloud to start spinning: the center having the highest angular velocity became extremely hot and dense comparatively, with a ring of gas and dust surrounding it, forming a proto star.
Overview Continued Of all the matter that composed the molecular cloud, the majority of the collapsing mass assembled in the center, forming what would later be the sun, while the rest flattened out into a protoplanetary disc with a diameter of 200 au, which would latter form the planets, moons and asteroids. The protoplanetary disc became thinner and thinner as the proto star pulled in more matter. Eventually particles in this disc began clumping. These clumps continued to add mass as they accumulated more particles- these clumps would eventually form the planets and moons in our solar system.
Overview Continued After more than 50 million years of spinning and gaining heat and density, the hydrogen in the center of the protostar was under enough pressure to begin thermonuclear fusion. The new star continued to grow in size, temperature, mass and density until it reached a state of hydrostatic equilibrium- at this point it became a main sequence star and the sun we know today. Close to the growing star only rocky materials could stand the growing intense heat. Therefore, most of the rocky material settled close to the sun, which is the reason that the planets of the inner solar system are composed of rock. The lighter and less dense material such as gas and ice settled in the outer part of the disc the reason for the gas giants of the outer solar system.
A Closer Look: Video Clip http://www.youtube.com/watch?v=-ht2yzscadc
Mercury Formed from a condensed nebula Created a dense metallic core with a thin silicate crust Asteroids bombarded the surface, internal lava flowed out and formed a new crust When the planet cooled and shrank, another wave of lava covered the old crust Mercury will remain unchanged for centuries!
Planetary Motion Stars and planets are formed when clouds of interstellar gas and dust collapse. Both the clouds and the material in these clouds are in constant motion. Thus, planets are formed in this state of motion. The rotation in these clouds is called angular momentum ; it is conserved ( The Law of Conservation of Momentum ) in our universe and it can be transferred but not created or destroyed.
Law of Conservation of Momentum For example, an http://www.youtube.com/watch?v=v3usrfha4
Why do some planets rotate differently? Almost all planets rotate in the same direction (counter-clockwise) and on the same plane. They spin in a direct sense that is, they spin in the same direction as they orbit the sun. (The gravity of the sun keeps the planets in their orbits) The two exceptions are Venus and Uranus. These differences are believed to stem from collisions early in their formation.
Venus Venus rotates backwards (clockwise) compared to the other planets. Why? Cratering evidence suggests that early in formation there were still many mini-planets orbiting the sun. It is thought that Venus encountered one of these planets and absorbed it into its own body. This body would have contributed angular momentum (along with kinetic energy and mass.) So, new spin and mass seriously altered the original spin of Venus, which was most likely similar to that of the other planets.
Earth Formed 4.5 billion years ago Travels in an elliptical orbit around the sun Has a velocity in a direction that is perpendicular to the force of the sun s pull (would travel in a straight line if the sun wasn t present) Kepler s Laws of Planetary Motion: 1 st law states that each planet travels along an ellipse, with the sun at one focus All planets rotate around themselves, BUT orbit around the sun!
A Theory on the Formation of the Moon A small planetary body hit the Earth late in its growth process, blowing out rocky debris A fraction of that debris went into orbit around the Earth It became the moon VOILA!! This is a good hypothesis because: The Earth has a large iron core, while the moon does not Earth s mean density of 5.5 grams/cubic cm, while the moon s mean density is 3.3 grams/cubic cm This correlates with moon s lack of iron The moon has exactly the same oxygen isotope composition as the Earth
Mars Direct accretion from grain particles in the protosolar nebula led to the creation of Mars, similar to planetary compositions like Earth and Mercury Formed after the formation of Jupiter Formed from a large planetesimal that separated from the asteroid belt
The Asteroid Belt Separates the first 4 terrestrial planets from the 4 outer gas-giant planets Between 2 and 4 astronomical units (avg. distance between the Earth and the Sun) Initially, the matter in the asteroid belt was enough to form 2-3 Earth-like planets As the planets migrated, the gravitational pulls created by Jupiter and Saturn excited the region, increasing the velocities relative to each other Currently has a total mass equivalent to about 1/2000 of the Earth s mass
The Asteroid Belt Continued There was a lot of debris left over from this formation. Some of the rocky material rotates around the sun in the asteroid belt, never fully coming together separating the gas planets from the rocky ones. Another asteroid belt that lies beyond Neptune is called the Kuiper belt. Most of the left over rocky debris formed the Oort cloud a giant spherical cloud of rock nearly a light year away from the sun. The remaining gas and small particles left over from the molecular cloud was blown away by the solar wind in the early years of the suns life.
Jupiter began with the build up of ice covered dust in the outer, cold solar nebula Small particles of ice and dust came together, forming larger and larger objects. Once it gathered together enough mass, its gravity attracted more dust, as well as hydrogen and helium. The heaviest elements sunk into the core of the planet, surrounded by the lighter hydrogen and helium in its atmosphere. 2.5 times bigger than any other planet in solar system Considered Failed Star, in that was once very hot and on the verge of stellar fusion but it cooled. Because of its immense gravity, scientists theorize that Jupiter was influential in the formation of other planets (like earth!).
Saturn Formed from a solar nebula about 4.6 Billion years ago a vast cloud of cold gas and dust which was disturbed somehow - perhaps by colliding with another cloud, or the shock wave from a supernova. cloud compressed down, forming a protostar in the center, surround by a flattened disk of material. Inner part of disc had heavier elements and created planets and other planetesimals. Outer disc made of ice. Rings created by deteriorating planet?
Uranus Uranus rotates on its side, 90 degrees relative to its original orbit. It too was likely hit by an early planetoid, causing it to have a skewed axial tilt. It has been described as having an axial tilt of 82 and a negative rotation of 17 hours, or, equivalently, of having an axis tilted at 98 and a positive rotation.
Neptune Much controversy as to how and especially where Neptune was formed. Solid, heavy matter core surrounded by gasses, ice and dust. Too far out for such matter to accumulate. Scientists suggest Migration Theory Theorized that the solid core came from remnants of the Kuiper Belt.
The Former Planet- Pluto Now considered the largest member of the distinct population called the Kuiper belt (composed of rock & ice, and is relatively small) Pluto doesn t orbit the sun in the same direction as the other planets do It s inclined at 18 degrees, which makes it more elliptic compared to the existing planets For a period of time it is closer to the sun than Neptune is, due to its eccentricity
Conclusion: The Future of the Solar System In an estimated 5.4 billion years thermonuclear fusion will no longer take place at the core of the sun. The entire supply of hydrogen will have been turned to helium. Once this happens, the sun will go from being a main sequence star to a red giant. The diameter of a red giant is typically 260 times larger than that of a main sequence star. The sun will decrease in temperature and over time the layers of the red giant will shed and leave in its place a white dwarf. Said white dwarfs would be incredibly dense, containing half the mass of the original star while having the same diameter as Earth.