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How Did the Solar System Come to Be?

How Did the Solar System Come to Be?. Observed Facts About Our Current Solar System. All the planets and asteroids move in the same direction around the sun. The sun rotates in the same direction as the planets spin. More Observations. 3. All the planets move in approximately the same plane.

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How Did the Solar System Come to Be?

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  1. How Did the Solar System Come to Be?

  2. Observed Facts About Our Current Solar System • All the planets and asteroids move in the same direction around the sun. • The sun rotates in the same direction as the planets spin.

  3. More Observations 3. All the planets move in approximately the same plane. 4. The composition of the outer planets are similar to that of the sun. 5. The composition of the inner planets are very rocky and very different from the sun.

  4. Question 1: Why do all the planets orbit the sun in the same direction, and why does the sun also rotate in this direction?

  5. A Proposed Theory The solar system began as a slowly rotating cloud of gas (mainly H and He) and dust (containing carbon, silicon, oxygen, etc.). Such clouds are also called nebula.

  6. The Cloud Collapses Due to gravity or a nearby supernova, our cloud collapses. As the cloud gets smaller, it spins faster.

  7. Gravity Inertia The Collapsing Cloud Stabilizes… But the faster a spinning object moves, the more force required to keep it from flying off (and thus to keep it in orbit). At some point, the inward force of gravity exactly balances this outward tendency to “fly off” (the object’s inertia) and the object enters a stable orbit about the center.

  8. Answer to Question 1: The planets orbit and the sun rotates in the same direction as the original cloud’s spin.

  9. Question 2: Why the disk?

  10. …And Becomes a Disk However, for an object NOT rotating around the center, there is NO inertia to oppose gravity and the object falls into the center. Ultimately, a disk forms. Gravity Gravity Inertia

  11. Any Evidence for this Theory?

  12. Example of a Disk:Beta Pictoris http://www.spaceref.com/news/viewpr.html?pid=20034

  13. Some of our Nebula still Remains Oort Cloud

  14. Question 3: How did the Sun and planets form?

  15. Anyone for a Lumpy Cloud? Over time, matter congregates together into lumps. The largest lump is in the center and is called the protosun. Eventually, it will ignite and form a star. Smaller lumps form in orbits around the protosun. The smaller lumps are called planetesimals and range in size from 1 km to a few 100 km.

  16. The Lumps Grow Planetesimals collide and merge with other planetesimals and form larger protoplanets. Some planetesimals still remain from the early days. We call them… Asteroids, Comets, and Meteorites, oh my!

  17. Protoplanets in Beta Pictoris?

  18. Make a Claymation Solar System! Include: Protosun Planetesimals Protoplanets

  19. Question 4: Why are the Innies so Rocky and the Outies so Sun-like?

  20. Hunk of Burnin’ Love The protosun grows as more matter is “sucked in”. Eventually, it ignites, forming a star. The heat and solar wind from the star blow away most of the gas and dust not already formed into planetesimals.

  21. Different Strokes for Different Folks Close to the new sun, it’s hot (duh). Much too hot for stuff like water to form. But cool enough for metals to condense and solidify out from the cloud. Farther out, it’s cooler and rocks and minerals form. Even farther out, it’s even cooler and water ice can form. Even farther out, it’s even colder, and ammonia and methane ice can form.

  22. How Composition Varies with Distance and Temperature

  23. Small, Rocky Inner Planets… The inner planets slowly formed as the metals and rocks slowly cooled and congregated together. Once the protostar ignited, leftover material was blown away. Thus… Inner planets are small. Thus… Inner planets have thin atmospheres (not enough gravity to capture and maintain gases, especially H and He).

  24. …And Huge, Gassy Outer Planets Meanwhile, ice quickly forms cores of the outer planets (several Earth masses). Thus… Greater mass of core allows a thicker atmosphere to be captured… Increasing mass of planet allows more gas to be captured… And the cycle continues until the new star blows away all the remaining gases.

  25. Talk About Picking on Your Little Brothers The gas giants’ gravity wreaks havoc on the smaller, inner planetesimals. Jupiter alone throws many planetesimals out of the now-known-as-the-asteroid belt zone. Some of these planetesimals are ejected outward and leave the solar system. Other planetesimals are sent inward where they collide with the inner planets, possibly bringing Earth water and carbonaceous compounds.

  26. In the blink of an eye… All this happened in about 100 million years. If the 13 billion years of the Universe were condensed into 1 day, this would be about 11 minutes.

  27. So How Old IS the Solar System? • Oldest Earth rocks: ~ 3.8 billion years old • Oldest Moon rocks: ~ 4.4 billion years old • Oldest Meteorites: ~ 4.5 billion years old Estimated age of solar system: 4.6 billion years

  28. Is Our Solar System Typical? Not really. Most have huge Jovian planets much closer to the sun than ours.

  29. What’s Up? Possible Explanations: • The bigger planets are simply easier to find. Smaller, rocky planets are there, too, if we could just see them. • Our theory’s wrong.

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