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Questions and Answers
Dust and grains surrounding the sun eventually formed clumps, leading to the creation of __________.
planetesimals
The __________ theory suggests that planets were formed from material ejected from the sun during an encounter with another celestial object.
Encounter
Uranus and Venus have a unique rotational pattern, spinning in a __________ direction unlike most other planets.
clockwise
The __________ theory indicates that particles surrounding celestial bodies attract one another, ultimately forming planets.
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Planetesimals formed as a result of __________ caused by the gravitational pull of an intruding star on the protosun.
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The solar system is believed to have formed from a rotating cloud of gas and dust known as the ______.
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Inner planets are composed mainly of materials with high melting points, such as silicates, iron, and ______.
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All planets in the solar system revolve around the sun in orbits that are ______.
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Outer planets are characterized by a dominance of ______ and larger sizes compared to inner planets.
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The period of revolution of planets increases with increasing distance from the ______.
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Study Notes
Growth of Planets
- Dust and grains around the Sun clumped together to form planetesimals.
- Planetesimals are small celestial bodies that fuse through collisions, leading to planet formation within the solar system.
Proponents of the Nebular Theory
- Emanuel Swedenborg (1688–1772)
- Immanuel Kant (1724–1804)
- Pierre-Simon Laplace (1749–1827)
Drawbacks of the Nebular Theory
- Dust particles around Saturn repel each other, challenging the idea of attraction leading to planet formation.
- The theory does not align with angular momentum laws, as the Sun would need to spin faster than observed.
- It does not explain the clockwise rotation of Uranus and Venus, contrasting with other planets' counterclockwise rotation.
Encounter Theory
- Proposes that planets formed from materials ejected from the Sun during a close encounter with another celestial object, like a star.
- A variant is the Planetesimal Theory, suggesting a passing star nearly collided with the protosun, causing material to be ejected and condensed into planetesimals.
Oscillating Universe Theory
- This theory suggests the universe will collapse after expansion, violating current physics laws, particularly regarding dark energy.
- Current predictions for the universe's end include the big freeze or heat death.
Solar System Characteristics
- Located in the Milky Way Galaxy, comprising at least 100 billion stars, spanning approximately 100 million light-years.
- The solar system revolves around the galactic center approximately every 240 million years.
- Age of the Earth and solar system approximated at 4.6 billion years, based on meteorite radioactive dating.
Large Scale Features of the Solar System
- Majority of the solar system's mass is concentrated in the Sun, while angular momentum is held by outer planets.
- Planetary orbits are elliptical and share a common plane, with revolution periods increasing with distance from the Sun.
- Inner planets are typically smaller and denser, while outer planets are gas-dominant and larger.
Small Scale Features of the Solar System
- Most planets exhibit prograde rotation.
- Inner planets consist of high melting point materials (silicates, iron, nickel) and usually have thinner or no atmosphere.
- Outer planets feature thick atmospheres, lower densities, and primarily consist of gases like hydrogen and helium.
Nebular Theory Overview
- The solar system formed around 4.5 billion years ago from a nebula, a giant cloud of gas and dust.
- Defined by NASA, nebulae consist of hydrogen, helium, and ionized gases.
Major Steps in Solar System Formation
- Cloud Collapse: Triggered by shockwaves from supernovae or nearby stars, causing gravitational collapse leading to increased spin.
- Formation of Protoplanetary Disk: Metallic materials near the Sun enable the formation of terrestrial planets, which have high boiling point compounds.
- Limited metallic resources restrict the growth of terrestrial planets, resulting in smaller diameters.
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Description
Explore the fascinating process of planet formation as described in the nebular theory. This quiz covers the crucial stages from dust and grains to the accretion of planetesimals. Learn about key proponents and their contributions to our understanding of this cosmic phenomenon.
