ASTR 100. Lecture 14: Formation of the Solar System and A Brief History of Space Exploration

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1 ASTR 100 Lecture 14: Formation of the Solar System and A Brief History of Space Exploration

2 Reading: Formation of SS (Ch. 6), The Sun (Ch. 10) Friday: Quiz and Ex. 4 due Tuesday: Feb 18 th : Midterm

3 Done with Grand Tour of the Solar System!

4 We know a lot of stuff about the Solar System now and can talk sensibly about why things are the way they are

5 Need a theory which explains all this Trends in the Solar System? -More volatiles further out -Inner planets are small and rocky -Outer planets are big and gassy -Everything rotates counter-clockwise (looking down at Earth s north pole) -Radiometric dating shows cratering slowed down 3.9 Gyr ago -Everything but the Oort cloud basically lies in the plane of the ecliptic -Exeptions to the rules

6 Right now you get half the theory (nebula theory) the second half comes after star death

7 In the beginning, there was a cloud 98% Hydrogen 1.4% Volatiles 0.4% Rocks 0.2% Metals all at degrees Kelvin (-240 C)

8 The cloud got shocked and began to collapse conservation of angular momentum cloud spins faster as it collapses The cloud also flattens, same process which makes Jovian planet rings

9 Voila: Proto-planetary disk All planets which form will lie in roughly the same plane

10 Temperature of the protoplanetar disk varies with distance from proto-sun < 0.3 AU, it s 2000 K even metal is vapor 4 AU, rock and metal solid, volatiles and Hydrogen gaseous frost line Beyond that, volatiles can condense

11 Condensed material started collecting into everlarger planetesimals, seeded by whatever material was condensed at that region Numerous, dinky planetesimals gathered under their own gravity into legit planets

12 Cleaning up, Part I: Removing the crumbs Now have some big things and some little things. Gravitational slingshot effect turns Solar System into a shooting gallery: Late Heavy Bombardment

13 Late, heavy bombardment explains a lot

14 Cleaning up, Part II Sweeping the dust The solar wind turns on, cleaning up all of the dust and gas which isn t gravitationally bound

15 How did we do? -More volatiles further out (Frost line) -Inner planets are small and rocky (High condensation temp) -Outer planets are big and gassy (Low condensation temp) -Everything rotates counter-clockwise (looking down at Earth s north pole) (Protoplanetary disk) -Radiometric dating shows cratering slowed down 3.9 Gyr ago (LHB) -Everything but the Oort cloud basically lies in the plane of the ecliptic (Protoplanetary disk) -Exeptions to the rules (LHB)

16 Of the 770 planetary systems we see, no other planetary system looks like ours. Jovian Planet much less than 1 AU from host star -->

17 Part of the story seems to be universal: Other planet-forming nebulae The Pillars of Creation

18 Have even seen proto-planetary disks around other, young stars/proto-stars

19 Quick, awful, incomplete, history of rocketry 1940 s Germans did some work 1926 first rockets Robert Stinky Goddard

20 Quick, awful, incomplete, history of Solar system exploration Oct Sputnik 1 - first to space Oct NASA created Jan Luna 1 - lunar orbit Mar Pioneer 4 - solar orbit Not as easy as it seems ( ): Pioneer 0 - destroyed on lauch pad Pioneer 1 - missed moon Pioneer 2 - engine failure fell back to Earth Pioneer P-1 - probe disappeared Pioneer P-3 - probe laucher malfunctioned Pioneer P-30 - missed lunar orbit Pioneer P-31 - probe lost

21 Favorable planetary alignment of the late 1970 s

22 X whoops Pioneer plaques fore teh aleeyunz

23 Voyager Golden Record

29 Newton s laws work pretty OK, I guess.

31 Voyager 1,2 and Pioneer 10, 11 leaving solar system

32 Key terms: Late Heavy Bombardment, protoplanetary disk, nebula theory, frost line, planetesimals Key Ideas: How did the conservation of angular momentum affect the formation of the Solar System? What role did temperature play in the formation of the solar system? What two processes cleaned up the small planetesimals and gas in the Solar System? Which parts of the Nebula Theory seem to hold up and which are do not seem to be correct? How do we know? We actually don t know, we suppose.

Lecture 10 Formation of the Solar System January 6c, 2014

1 Lecture 10 Formation of the Solar System January 6c, 2014 2 Orbits of the Planets 3 Clues for the Formation of the SS All planets orbit in roughly the same plane about the Sun. All planets orbit in the