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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: Processes that produced these solar wanders?
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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: • Processes that produced these solar wanders? • The materials that were the building blocks of terrestrial planets. • The early processes of accretion. • 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 - Planets According to IAU: • 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. • 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% H2 • ~ 9% He • CO2, H2O, HCN • Dust! • Mass = 100-106 M • Size = 50 to 100’s pc • 1 pc = 3.08 1016 m or 3.3 Ly or 63, 241 AU • Star forming factories NGC 2074 R = S, G = H, B = O2
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 = O2
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. Color 2. Luster • 3. Streak 4. Hardness • 5. Cleavage 6. Fracture • 7. Crystal Form 8. 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 = 1 Gypsum = 2 Calcite =3 • Flourite = 4 Apatite = 5 K Feldspar= 6 • Quartz = 7 Topaz = 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: Mg2Si2O6; Fe2Si2O6, Ca2Si2O6; CaMgSi2O6; CAFeSi2O6 • Olivine: (Mg,Fe)2SiO4 • Feldspars: NaAlSi3O8; CaAl2Si2O8 • Quartz: SiO2 • Spinels: MgAl2O4 - FeAl2O4 - Fe3O4-FeCr2O4