solar storm movies from solar dynamics observatory search SDO

Transcription

1 solar storm movies from solar dynamics observatory search SDO

2 diverse planetary environments distance from sun : 0.4 è 40AU size/mass : Mercury : 5%M,0.4R è Jupiter--318M,11R composition/structure : inner--fe,ni,si outer--h,he,ch 4 website w/ NASA photos,etc :

3 solar system inventory : sun 9 planets : Terrestrial -- mercury, venus, earth, mars Jovian -- jupiter, saturn, uranus, neptune, pluto (?) total mass = 447 M 170 moons (Jup/Sat each!) = 0.12 M earth thousands asteroids (2.9 AU) : 6 w R > 300 km, 10 6 < 1 km hundreds KBOs at 40AU : few km comets : thousands at > 50 AU (Oort cloud) Zodiacal dust total mass (mostly in Jupiter/Saturn) = M sun / 743

4 orbits : all in same direction coplanar (except Pluto) è common & single epoch of origin

5 strong evidence that our solar system formed from one rotating cloud (rather than by capture or agglomeration) almost everything w/i solar system rotates or orbits in same direction (ccw when viewed from above north pole) exceptions : orbits -- Mercury (7 0 ) ; Pluto (17 0 ) rotation -- Venus (cw) ; Uranus & Pluto (poles in eclip.) oldest earth rocks ~ 3.4 billion yrs old oldest lunar rocks ~ 4.48 billion yrs old 2 modes of planetary growth : agglomeration of small solid bodies (up to 15 M earth ) gravitational accretion of gas (above 15 M earth )

6 planetary formation & growth : 2 mechanisms : agglomeration of solids -- up to 15 M earth solids : silicates, metals, ices (H 2 O, CO 2, NH 3 ) ices only at < 300K ==> at large radii gravitational accretion of gas -- above 15 M earth time ==> 10 6 yr 10 7 yr 3x10 7 yr

7 3-phases in solar system formation : spherical collapse of cloud core star w/ accreting planetessimals rotating dust& gas disk w/ protostar

8 two very different classes of planets!! terrestrial planets formation or evolution?? è distance from sun critical rocky solids WHY?? gas giants Jovian planets

9 temperatures of planets solar radiation (visible) R planet s reradiation (IR ~ 10-20micron) thermal steady state ==> T solar heating = reradiation by planet (L/4πd 2 ) πr 2 (1-A) = 4πR 2 σt 4 A= albedo or reflectivity (high for clouds), e.g. A earth ~30% (moon ~ 7%) è T (1-A) 1/4 L 1/4 d 1/2 for A=0 (blackbody), T = 278 (L sun /d 2 AU) 1/4 K, varies as d -1/2

10 T decreases w/ increasing distance from proto-sun (higher L) è different solids condense at different T ==> distances è condensation sequence : 1500K -- metal oxides 1300K -- metallic iron/nickel 1200K -- silicates 175 K -- H 2 O ice 120 K -- CH 3 (methane) ice terrestrial vs jovian planets due to non-condensation of mol. w/ H close to sun (H 2 O & CH 3 ) w/o H (80% of mass) can t grow large no fast gravitational growth only rocky / metallic è only get very massive planets in outer sol. sys.

11 retention of atmosphere? for gas, <KE> = 3/2 kt ==> v = (3 kt / m molecule ) 1/2 è higher v for higher T & lower mass molecules for a planet, v escape = ( 2GM/R ) 1/2 rule of thumb : if v thermal >~ 0.1 v esc è gas will escape and inner planets have higher T 3/2 kt = ½ mv 2 è v = 3 (T 300K /m AMU ) 1/2 km/s è close in (hot), low mass planets can t retain light atmospheric molecules Mercury 4 Venus 10 Earth 11 Moon 2 Mars 5 V esc (km/s) Jupiter 60

12 Mercury orbit : 0.47AU <=> 70x10 6 km 3 rotations per 2 orbits no atmosphere T = 467C to -170C?? contracted during early cooling phase

13 Caloris basin formed by huge impact w/i first billion yrs ~1000 km

14 Venus covered w/ thick clouds in visible & UV rotates retrograde? explanation never gets more than 47 0 from sun => called morning/evening star

15 extremely hot, dense atmosphere mainly CO 2, H 2 SO 4 droplets absorbs cooling IR re-radiation è runaway greenhouse effect 90 atm. (= pressure 900m down in ocean)

16 thermal steady state must now include atmospheric absorption solar radiation (visible) venus s reradiation (IR ~ 10-20micron) solar heating = re-radiation by Venus (L/4πd 2 ) πd 2 (1-A) = 4πR 2 σt 4 β A = albedo or reflectivity β = escape fraction of venus s radiation è T (1-A) 1/4 L 1/4 d 1/2 / β 1/4 β < 1 (due to atm. absorption) ==> T is higher

17 terrestrial greenhouse effect : water vapor 36 72% carbon dioxide 9 26% methane 4 9% ozone 3 7% ~30% reflected (moon s 7%) 340 W/m 2

18 Venus surface image made how? +- 6 km height ~1000 volcanoes Fe core 3000 km radius

19 Maat Mons volcano -- 8 km high w/ lava flows

20 Mars -- most like earth -- similar T, tenuous atm. + dust storms both hemispheres imaged 11 hrs apart by Hubble è polar icecap, clouds & volcanoes huge amounts of H 2 O, but few m below surface

21 Valle Marinaris 3000 km long! 8 km deep 3 tharsis volcanos Viking spacecraft 1980

22

23 Olympus Mons 600 km diam. 25 km high (~80,000 ft)

24

25 Polar caps CO 2 + H 2 O ice

26 evidence of past liquid flows -- water

27 Mars moons : Phobos & Deimos Phobos 10 km

28 <density> = 1.3 gr/cc H + He + trace sulfur & NH 3 dense atm. w/ cyclones liquid è solid core Jupiter w/ Ganymede

29 atmosphere interior

30 Red Spot ~50,000 km red spot : colder & higher in atm.

31 Jovian moons

32 major moons in sol. sys. : jupiter moons

33 Io -- very active vulcanism rotates synchronous w/ orbit eccentric orbit (due to Europa) è tidal heating of interior (100 m stretching of surface) motion in Jupiter s B-field è 4x105V across IO è 3x106amps è ionic ejection and Jup. aurora

34 Jupiter aurora & lightning & extreme mag. fields ( ~20,000 x earth s ) Terrestrial whistlers khz

35 resonances also responsible for IO s eccentric orbit Keplar s law p 2 = d 3 Ganymede 4:1 Europa 2:1 IO 1:1 Jupiter

36 Europa -- similar to our moon, but tidally heated by Jupiter è covered by frozen salt water tides è fractures fractured ice surface

37 Ganymede cratered icy surface Callisto heavily cratered solid surface

38 Comet Shoemaker-Levy comet impact (7/94)

39 Saturn : Casini image -- visible <=> IR density 0.69 gr/cc belt zones like Jupiter but methane haze è less visible rings & 62 moons : Titan : largest ~ 1.5 x moon atmosphere w/ methane and nitrogen smog surface -- cold (179K) ice due to reverse greenhouse (smog blocks sunlight)

40 rings -- icy rocks Casini -- passing through ring plane w/ moon Pan in Encke gap

41 radio waves measure size of ring particles purple => > 2 in green ==> < 2 in blue ==> < 1/3 in white -- opaque radio transmitter (λ=0.6, 3.6 and 13 cm) on Casini passes behind rings and signal detected on earth

42 Cassini spacecraft image of Saturn eclipsing sun 9/15/2006

43 moons cause gaps in rings due to resonant grav. perturbations Cassini gap due to 2:1 resonance with moon Mimas B A

44 H, He, methane ice methane absorbs red light è uranus and neptune appear blue