ASTR 200 : Lecture 6 Introduction to the Solar System 1 2004 Pearson Education Inc., publishing as Addison-Wesley
Comparative Planetology Studying the similarities among and differences between the planets this includes moons, asteroids, & comets This approach is useful for learning about: the physical processes which shape the planets the origin and history of our Solar System the nature of planetary systems around other stars 2 2004 Pearson Education Inc., publishing as Addison-Wesley
Basic patterns that need explanation All planets orbit Sun in same sense (counterclockwise viewed from N) All planets orbit in almost same plane, with e~0 Sun contains 99.9% of Solar System's mass Inner planets are rocky, while outer the planets/satellites are icy or gas-rich Crater production (especially impact basins) larger in past 3 2004 Pearson Education Inc., publishing as Addison-Wesley
An obvious solar system division Planets fall into two main categories A) Terrestrial (i.e. Earth-like) B) Jovian (i.e. Jupiter-like or gaseous) 4 Danger: Inner and Outer are often used, but they only work until Neptune 2004 Pearson Education Inc., publishing as Addison-Wesley
5 Mars Terrestrial 2004 Pearson Education Inc., publishing as Addison-Wesley Neptune Jovian
6 2004 Pearson Education Inc., publishing as Addison-Wesley
7 2004 Pearson Education Inc., publishing as Addison-Wesley
8 2004 Pearson Education Inc., publishing as Addison-Wesley
The Layout of the Solar System Large bodies in the Solar System have orderly motions - planets orbit counterclockwise in same plane - orbits are almost circular - the Sun and most planets rotate counterclockwise (seen from N) - most moons orbit their planet counterclockwise 9 2004 Pearson Education Inc., publishing as Addison-Wesley
A Few Exceptions to the Rules Both Uranus & Pluto are tilted on their sides. Venus rotates backwards (i.e. clockwise). Triton orbits Neptune backwards. Earth is the only terrestrial planet with a relatively large moon. Is Pluto (and other large trans-neptunian objects) to be considered a planet? 10 2004 Pearson Education Inc., publishing as Addison-Wesley
The Sun King of the Solar System How does the Sun influence the planets? Its gravity regulates the orbits of the planets. Its heat is the primary factor which determines the temperature of the planets. It provides practically all of the visible light in the Solar System. High-energy particles streaming out from the Sun influence planetary atmospheres and magnetic fields. 11 2004 Pearson Education Inc., publishing as Addison-Wesley
Mercury : Battered Remnant Recently explored by the Messenger spacecraft Impact scarred like our Moon 12 2004 Pearson Education Inc., publishing as Addison-Wesley
Venus: An extreme climate Earth's twin in size Massive choking atmosphere Clue to planetary climates 13 2004 Pearson Education Inc., publishing as Addison-Wesley
Earth: The cradle of life A complex biosphere A massive Moon Geologic complexity 14 2004 Pearson Education Inc., publishing as Addison-Wesley
Mars : The most likely second home? Earth-like in some ways Perhaps had oceans? Surface has great variety 15 2004 Pearson Education Inc., publishing as Addison-Wesley
Jupiter : Lord of the heavens More mass than all other planets put together First of the jovian planets Moons the size of planets 16 2004 Pearson Education Inc., publishing as Addison-Wesley
Ringed Saturn Rings are incredibly flat Interesting contrasts to Jupiter 17 2004 Pearson Education Inc., publishing as Addison-Wesley
Uranus and Neptune : the ice giants Much smaller than Jupiter and Saturn Dominantly ices, not gases 18 2004 Pearson Education Inc., publishing as Addison-Wesley
The Solar System has two 'small body belts' 19 2004 Pearson Education Inc., publishing as Addison-Wesley
Comets and Asteroids Small bodies that hold big clues to the birth of planets The two classes are mainly composition Rocky asteroids Icy comets This is linked to where they formed. 20 2004 Pearson Education Inc., publishing as Addison-Wesley
The main asteroid belt Swarms of asteroids and comets populate the Solar System Rocky asteroids, mostly between Mars and Jupiter 21 2004 Pearson Education Inc., publishing as Addison-Wesley
Neptune's orbit Comets Pluto's orbit - Visible comets (those with tails) when they make it to the inner Solar System (rare) Reservoirs are the : - Kuiper Belt - Oort cloud Oort cloud Main asteroid belt 22 2004 Pearson Education Inc., publishing as Addison-Wesley
New perspectives from Exoplanets Now that we are able to detect and study planets around other stars, it is known that there are planetary configurations quite different from those in our Solar System Hot Jupiters Jupiter scale objects very close to their stars Multi-`super Earth' systems, in close 2-7 planets each of several Earth radii Very distant giant planets Out at 50-200 au from their stars 23 2004 Pearson Education Inc., publishing as Addison-Wesley