Transcript Document

How did the Solar System form?
Biggest question in all of geosciences!
Question: How did the Solar System form?
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More specifically:
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How did the terrestrial planets form?
How do we constrain:
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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?
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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:
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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 selfgravity 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
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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 - 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.
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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
Minerals
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
Minerals
Minerals
Minerals
• How do you identify minerals?
– By the physical properties they exhibit.
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1. Color
3. Streak
5. Cleavage
7. Crystal Form
2. Luster
4. Hardness
6. Fracture
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.
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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