AST 115 1st Edition Lecture 14 Outline of Last Lecture I. Regulatories of the Solar Systema. Characteristics of the 8 major planetsb. Terrestrial and Jovian planetsII. Age of the Solar SystemIII. Building Materials for the Solar Systema. Basic “ingredients”IV. Solar Nebula Theory and the “Nice Model”Outline of Current Lecture I. Formation of the Outer Planetsa. Jupiterb. Saturnc. Neptuned. UranusII. Formation of the Inner Planetsa. Mercuryb. Venusc. Earthd. MarsIII. Leftover Debris from the Construction ProcessIV. Categories of Changing ClassificationsCurrent Lecture Formation of the Outer Planetso Jupiter formed ahead of all of the other major planets and used up most of the available raw material.- Saturn, Neptune, and Uranus came next.o The Jovian planets are believed to have formed from “seeds” consisting of rocky, metallic objects similar to our current terrestrial planets, formed by millions of years of accretion.o Jupiter formed at a distance of about 3 A.U. from the Sun (Jupiter’s current distance from the Sun is about 5 A.U.)These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Jupiter formed just outside of the snow line. Here, it accumulated huge amounts of Hydrogen (H) and Helium (He).- It “cleared the neighborhood” in a disk of raw materials.o Saturn was the next to form a few million years after Jupiter. It was much closer to Jupiter than it is now. o Neptune was the third planet to form and Uranus was the last of the Jovian planets to form.- Uranus and Neptune must have had less H and He available to them than Jupiter and Saturn.o Gravitational interplay allowed the Jovians to migrate to their current positions.o This resulted in Uranus and Neptune switching positions, leaving Neptune as the outermost planet. Formation of the Inner Planetso The Terrestrial planets must have formed somewhat after the Jovians as a result of collisions of Moon-sized “planetesimals” of rocky/metallic composition aided by debris spiraling in from beyond the snow line as the 4 giants’ orbits changed.o The Terrestrials were built from “seeds” in nearly circular orbits, or the collision process favored the survival of planetesimals in low-eccentricity orbits.- One of the last major collisions with Earth apparently led to the creation of the Moon).o They reached their current diameters by about 4.1 billion years ago.o The “Late Heavy Bombardment” (LHB) began then, fueled by debris cast inward from beyond the snow line by the migration of the Jovians.- Ended by 3.8 billion years ago. Any surface water came from the icy planetestimals from beyond the snow line.- Only Earth retains significant amounts of this liquid water in its vast and deep oceans.o Craters on the Terrestrial planets and the Jovian moons attest to the later stages of accretion process. Leftover Debris from the Construction Processo While solid debris had been sent to the inner solar system, icy debris propelled out beyond Neptune’s orbit. This produced the Kuiper Belt.- The Kuiper Belt is a torus of icy debris in the plane of the ecliptic, extending from about 30 to 500 A.U. from the Sun. It is doughnut shaped.- The Oort Cloud is the vast spherical distribution of icy debris extending out to about 50,000 A.U. from the Sun.- Inhabitants of the Kuiper Belt as called “Kuiper Belt Objects” (KBO). Pluto is considered a KBO and it is only the second largest in diameter, but it was the first discovered.- Few asteroids stray from this main belt. Categories of Changing Classificationso Pluto was re-classified as a Dwarf Planeto The tiniest remnants of the formation process are called “Small Solar System Bodies” (SSSB).- These include smaller asteroids, comets, satellites of planets, and
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