Interiors of Worlds and Heat loss

1. Interiors of Worlds and Heat loss

2. Differentiation -materials separate into layers

3. How do we learn about planetary interiors? • Measure moment of inertia & average density • Observe seismic events • Study planetary magnetic fields

5. waves travel in straight lines unless diverted by the material they travel through. • refract due to density changes. • refract due to composition changes • reflect dues to boundary changes

7. What does a Planetary Magnetic Field look like?

8. Interiors and Magnetic Fields We can deduce that any world with a global magnetic field has 2 things: • It has an electrically conducting material within it. • The material is a moving, circulating liquid. (movement usually caused by the rapid rotation of a planet)

9. Interiors and Magnetic Fields Terrestrial Worlds like Earth have a 3rd • It has an electrically conducting material within it. • The material is a moving, circulating liquid. • It has two internal layers composed of a solid layer inside a liquid one.

10. Interior of our planet

11. Main Worlds with Active Magnetic Fields Strength Order: Sun, Gas giants, Earth, Mercury, Mars (remnant)

12. Interior of Terrestrial Worlds

13. Interiors: Gas Giant v.s Terrestrial

14. Interior of Gas Giant Worlds The magnetic fields of gas giants indicate that there are large amounts of circulating, electrically-conducting materials. Metallic hydrogen or water

15. Total Magnetic Field Shape

16. Heat loss

17. Planets gain their initial internal heat energy by 3 main methods:- Kinetic Gravitational Radioactivity

18. Planet spend the rest of their lives losing internal energy to space

19. 3 Types of Heat loss • Conduction -atoms vibrate strongly causing atoms next them to pick up energy • Convection- heat causes fluids to move, the hot fluid rises, the cold fluid sinks. • Radiation- photons of electromagnetic light carry energy away from the object

20. Which Forms of Heat Loss Work Where? • All worlds conduct inside. • All worlds radiate out to space (the only heat transfer that works in a vacuum!). • Larger worlds convect inside. • Largest worlds radiate inside.

21. Dominant Form of Internal Heat Loss Conduction -all small bodies: asteroids, comets, small only moons, Mercury, Moon, modern Mars Convection cells break the crust causing the surface to move with the convection -Earth Solid Convection cells heat the crust causing melting and volcanism Convection- Venus, early-middle Mars,earliest Moon and Mercury Gas-Sun(outer layers), gas giant planets all wavelengths -internal layer deep in theSun Radiation weakly at IR and longer for other worlds

22. Solid Convection Causing Volcanism

23. Solid convection causing movement, but no crustal break-up

24. Solid convection causing crustal break-up (Earth only)

25. Earthquakes along break-lines

26. Radiation inside Worlds • The hotter the world, the stronger the black-body curve and the more and shorter-wavelength radiation it emits. • Sun: hottest, visible light • Gas giants : IR • Rocky: some reflected radiation (not a black-body), some IR, some microwave and radio.

27. Radiation inside Worlds • The Sun has an internal zone where electro-magnetic radiation is emitted.