How did the Solar System form? Biggest question in all of geosciences!

Question: How did the Solar System form? More specifically: –How did the terrestrial planets form? How do we constrain: 1.Processes that produced these solar wanders? 2.The materials that were the building blocks of terrestrial planets. 3.The early processes of accretion. 4.The process of differentiation from planetesimal to planet.

Techniques What techniques are used in observational astronomy? –Optical observations –Electromagnetic spectrum observations (spectroscopy).

Techniques What techniques are used in observational geosciences? –Petrographic microscope –SEM –EMP –ICP-MS, LA-ICP-MS –SIMS, TIMS –FIB, TEM etc.

Best approach to solving the problem? Blending geological investigations with astronomical observations and astrophysical calculations.

What are we interested in within this course? Geological sciences and rocks!

Solar System formation

Solar System formation - Planets According to IAU: 1.A planet is a celestial body that (2) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape and (c) has cleared the neighborhood around its orbit. 2.A ‘dwarf planet’ is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self- gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round shape), (c) has not cleared the neighborhood around its orbit, and (d) is not a satellite.

Solar System formation - Planets According to IAU: 3. All other objects except satellites, orbiting the Sun shall be referred to collectively as “Small Solar System Bodies”.

Solar System formation - Molecular clouds Molecular Clouds ~ 90% H 2 ~ 9% He CO 2, H 2 O, HCN Dust! Mass = M  Size = 50 to 100’s pc –1 pc = m or 3.3 Ly or 63, 241 AU Star forming factories NGC 2074 R = S, G = H, B = O 2

Solar System formation - Molecular clouds How do they form? What are their structure? What are the initial conditions for star formation? –Self collapse or shock wave What is the efficiency for forming stars? What is the interaction between stars and cloud? Number of stars form! NGC 2074 R = S, G = H, B = O 2

Solar System formation - Molecular clouds

Solar System formation - Initial What occurs in the earliest stages of cloud collapse? –Protostar is formed (here we will leave this issue for the purpose of being focused). What is the age of the Solar System and what defines T = 0? –Calcium-rich, aluminum-rich inclusions within chondritic meteorites. These are rocks and thus are composed of minerals.

Solar System formation - Meteorites What are meteorites and how are they classified? To answer this, we need to know some basic concepts about minerals and rocks. So we’ll digress for a few minutes.

Minerals Mineral = an inorganic crystalline solid that is found as a single uncombined element or chemical compound and is naturally occurring. –It must be naturally occurring. –It must be inorganic. –It must be a solid. –It must have a definite chemical structure. –It must have an orderly arrangement of atoms. Mineralogy = The study of minerals.

Minerals

Why should you care about minerals? –1. They are natural resources. They can be gem stones or of other economic value (e.g., contain Iron (Fe), etc.). –2. They are the building blocks of rocks!

Minerals Crystal = a geometric solid with flat surfaces or faces and is a external expression of an orderly arrangement of atoms. –Glass is not a mineral. It is not crystalline, it is amorphous (atoms not arranged orderly). Opal, window glass, etc.

Minerals 8. Specific gravity = compares the weight of a mineral to the weight of an equal volume of water. How much heavier than water is the mineral. –Similar to density.

Minerals

How do you identify minerals? –By the physical properties they exhibit. 1. Color2. Luster 3. Streak4. Hardness 5. Cleavage6. Fracture 7. Crystal Form8. Specific Gravity

Minerals 1. Color = self-explanatory. It is not, however, very reliable and great caution is needed when using this property. 2. Luster = the appearance or quality of light to reflect or refract from the surface of a mineral.

Minerals 3. Streak = the color of a mineral in its powdered form. 4. Hardness = the measure of the resistance of a mineral to abrasion or scratching.

Minerals Mohs scale of ardenss. It is a relative scale to reference the hardness of minerals. –Talc = 1Gypsum = 2Calcite =3 –Flourite = 4Apatite = 5 K Feldspar= 6 –Quartz = 7Topaz = 8 Corundum = 9 –Diamond = 10

Minerals 5. Cleavage = the tendency of a mineral to cleave or break along planes of weak bonding. Produces distinctive smooth surfaces with geometric forms. 6. Fracture = the tendency of a mineral to break. Produces rough surfaces.

Minerals 7. Crystal Form = the external expression of a mineral’s internal orderly arrangements of atoms.

Minerals Isometric (or cubic): block shaped (diamond, salt) Tetragonal: pyramid shaped (zircon) Hexagonal: six sided (beryl) Orthorhombic: shot, three unequal axes, right angles (topaz) Monoclinic: stubby, tilted faces, unequal axes, right angles (gypsum) Triclinic: flat, sharp edges, no right angles, unequal axes (feldspar)

Minerals Some common minerals on Earth and meteorites: Pyroxene: Mg 2 Si 2 O 6 ; Fe 2 Si 2 O 6, Ca 2 Si 2 O 6 ; CaMgSi 2 O 6 ; CAFeSi 2 O 6 Olivine: (Mg,Fe) 2 SiO 4 Feldspars: NaAlSi 3 O 8 ; CaAl 2 Si 2 O 8 Quartz: SiO 2 Spinels: MgAl 2 O 4 - FeAl 2 O 4 - Fe 3 O 4 -FeCr 2 O 4