UNIVERSE
• The universe as we currently know it comprises all space and time, and all matter & energy in it.
• It is made of 4.6% baryonic matter (“ordinary” matter consisting of protons, electrons, and neutrons: atoms,
planets, stars, galaxies, nebulae, and other bodies), 24% cold dark matter(matter that has gravity but does not emit
light), and 71.4% dark energy (a source of antigravity)
• Dark matter can explain what may be holding galaxies together for the reason that the low total mass is insufficient
for gravity alone to do so while dark energy can explain the observed accelerating expansion of the universe.
• Hydrogen, helium, and lithium are the three most abundant elements.
• Stars - the building block of galaxies born out of clouds of gas and dust in galaxies . Instabilities within the clouds
eventually results into gravitational collapse, rotation, heating up, and transformation to a protostar-the core of a future
star as thermonuclear reactions set in.
• Stellar interiors are like furnaces where elements are synthesized or combined/fused together. Most stars such as the
Sun belong to the so-called “main sequence stars.” In the cores of such stars, hydrogen atoms are fused through
thermonuclear reactions to make helium atoms. Massive main sequence stars burn up their hydrogen faster than smaller
stars. Stars like our Sun burn up hydrogen in about 10 billion years.
• The remaining dust and gas may end up as they are or as planets, asteroids, or other bodies in the accompanying
planetary system.
• A galaxy is a cluster of billions of stars and clusters of galaxies form superclusters. In between the clusters is practicallyan
empty space. This organization of matter in the universe suggests that it is indeed clumpy at a certain scale. But at a large
scale, it appears homogeneous and isotropic.
• Based on recent data, the universe is 13.8 billion years old. The diameter of the universe is possibly infinite but should
be at least 91 billion light-years (1 light-year = 9.4607 ×1012km). Its density is 4.5 x 10-31g/cm3.
EXPANDING UNIVERSE
• In 1929, Edwin Hubble announced his significant discovery of the “redshift” (fig. 5) and its interpretation that galaxies
are moving away from each other, hence as evidence for an expanding universe, just as predicted by Einstein’s
Theory of General Relativity.
• He observed that spectral lines of starlight made to pass through a prism are shifted toward the red part of the
electromagnetic spectrum, i.e., toward the band of lower frequency; thus, the inference that the star or galaxy must be
moving away from us.
ORIGIN OF THE UNIVERSE
a. Non-scientific Thought
• Ancient Egyptians believed in many gods and myths which narrate that the world arose from an infinite sea at the first
rising of the sun.
• The Kuba people of Central Africa tell the story of a creator god Mbombo (or Bumba) who, alone in a dark and watercovered Earth, felt an intense stomach pain and then vomited the stars, sun, and moon.
• In India, there is the narrative that gods sacrificed Purusha, the primal man whose head, feet, eyes, and mind became
the sky, earth, sun, and moon respectively.
• The monotheistic religions of Judaism, Christianity, and Islam claim that a supreme being created the universe, including
man and other living organisms
b. Scientific Thought
Steady State Model
• The now discredited steady state model of the universe was proposed in 1948 by Bondi and Gould and by Hoyle.It
maintains that new matter is created as the universe expands thereby maintaining its density.
• Its predictions led to tests and its eventual rejection with the discovery of the cosmic microwave background.
Big Bang Theory
• As the currently accepted theory of the origin and evolution of the universe, the Big Bang Theory postulates that 13.8
billion years ago, the universe expanded from a tiny, dense and hot mass to its present size and much cooler state.
Evolution of the Universe according to the Big Bang Theory
• From time zero (13.8 billion years ago) until 10-43 second later, all matter and energy in the universe existed
as a hot, dense, tiny state (fig. 7). It then underwent extremely rapid, exponential inflation until 10-32 second
later after which and until 10 seconds from time zero, conditions allowed the existence of only quarks, hadrons, and
leptons.
• Then, Big Bang nucleosynthesis took place and produced protons, neutrons, atomic nuclei, and then hydrogen, helium,
and lithium until 20 minutes after time zero when sufficient cooling did not allow further nucleosynthesis.
• From then on until 380,000 years, the cooling universe entered a matter-dominated period when photons
decoupled from matter and light could travel freely as still observed today in the form of cosmic microwave background
radiation.
• As the universe continued to cool down, matter collected into clouds giving rise to only stars after 380,000 years and
eventually galaxies would form after 100 million years from time zero during which, through nucleosynthesis in stars,
carbon and elements heavier than carbon were produced.
• From 9.8 billion years until the present, the universe became dark-energy dominated and underwent accelerating
expansion. At about 9.8 billion years after the big bang, the solar system was formed.
SOLAR SYSTEM
• The solar system is located in the Milky Way galaxy a huge disc- and spiral-shaped aggregation of about at least
100 billion stars and other bodies.
• Its spiral arms rotate around a globular cluster or bulge of many, many stars, at the center of which lies a supermassive
blackhole;
• This galaxy is about 100 million light years across (1 light year = 9.4607 ×1012km;
• The solar system revolves around the galactic center once in about 240 million years;
• The Milky Way is part of the so-called Local Group of galaxies, which in turn is part of the Virgo supercluster of galaxies;
• Based on the assumption that they are remnants of the materials from which they were formed, radioactive
dating of meteorites, suggests that the Earth and solar system are 4.6 billion years old on the assumption that they
are remnants of the materials from which they were formed.
Large Scale Features of the Solar System
• Much of the mass of the Solar System is concentrated at the center (Sun) while angular momentum is held by
the outer planets.
• Orbits of the planets elliptical and are on the same plane.
• All planets revolve around the sun.
• The periods of revolution of the planets increase with increasing distance from the Sun; the innermost planet
moves fastest, the outermost, the slowest;
• All planets are located at regular intervals from the Sun.
• Much of the mass of the Solar System is concentrated at the center (Sun) while angular momentum is held by
the outer planets.
• Orbits of the planets elliptical and are on the same plane.
• All planets revolve around the sun.
• The periods of revolution of the planets increase with increasing distance from the Sun; the innermost planet
moves fastest, the outermost, the slowest;
• All planets are located at regular intervals from the Sun. Venus, Earth, and Mars are part of the inner terrestrial or "rocky"
planets. Their composition and densities are not too different from each other.
• Venus is considered to be the Earth's twin planet. It has a very similar size and mass with the Earth. Mars is about half
the Earth's size.
• Orbital period and velocity are related to the planet's distance from the sun. Among the three planet, Venus is the
nearest and Mars is the farthest from the Sun.
• Rotational speed of Earth and Mars are very similar. Rotational speed of Venus is extremely slow.
• Abundance of liquid water on Earth, hence the blue color. The Earth is a habitable planet.
ROCKS AND MINERALS
• Minerals
A. What is a mineral?
1. Occur naturally
2. Solid
3. Inorganic
4. Definite chemical composition
5. Atoms are arranged in an orderly pattern
• How to ID Minerals
B. Physical properties of a mineral:
1. Color
a. 1st recognizable pattern
b. least useful – more than 1 mineral are the same color
• Mineral Color Continued
• Example 1:
Same color minerals
– Quartz
– Halite
– Calcite
• Mineral Color Continued
• Example 2: Minerals can have more than one color
• Such as the minerals
– Quartz (clear, rose)
– Fluorite (purple, green, yellow)
• Physical Properties Continued
2. Luster: The way a mineral reflects light
a. Metallic – looks like a metal
b. Non Metallic – pearly, waxy, glassy, dull
• Physical Properties Continued
3. Streak – color of a mineral in its powdered form. Color can be the same or different from the original sample or have
no streak at all.
• Physical Properties Continued
4. The way it breaks
a. Cleavage: breaks along flat surfaces
Minerals w/ Cleavage
– mica, halite
b. Fracture: breaks unevenly
Minerals w/out Cleavage
–
sulfur, talc
• Physical Properties Continued
5. Hardness
a. Moh’s Hardness Scale – Unknown minerals hardness is compared to a
known value on a scale 1-10(hardest)
• What is a Rock?
Definition: One or more minerals boundtogether in earth’s crust.
Monomineralic: ex: Limestone – calcite (CaCO3), Quartzite – quartz (SiO2)
Polymineralic: (the majority of rocks) ex: Granite (quartz, feldspar, mica etc.)
• How to Classify Rocks
Rocks are classified based on the environment (process) of formation:
1. Igneous Rocks
2. Sedimentary Rocks
3. Metamorphic Rocks
IGNEOUS ROCKS - Rocks which formed by molten rock (magma or lava) that cools and solidifies.Igneous rocks form the
bulk of earth’s crust.
Examples: Obsidian, Basalt, Granite
Intrusive (Plutonic) rocks formed deep within the crust. Because they were so deep they cooled very slowly giving the
mineral crystals in the rocks a very long time to grow. That’s why intrusive igneous rocks usually have a coarse to very
coarse texture. Granite, Diorite, Gabbro, Peridotite and Dunite are the names of the coarse grained igneous rocks. These
rocks are INTRUSIVE (Plutonic) rocks. INTRUSIVE = SLOW COOLING = COARSE TEXTURE
Igneous rocks with fine texture have grain sizes less than 1mm. Theserocks formed at or near the surface and are called
EXTRUSIVE(Volcanic) rocks.Because they formed at or near the surface they cooled rapidly. Their crystals (grains) had
very little time to grow so they remain small. Rhyolite, Andesite, and Basalt are the fine grained igneous rocks.
EXTRUSIVE = RAPID COOLING = FINE TEXTURE
SEDIMENTARY ROCKS - Rocks which form by deposition under water
Two mechanisms: 1. Cementation or compaction
2. Evaporation – water leaves behind minerals – aka precipitates (rock salt)
• Types of Sedimentary Rocks
1) Clastic (broken pieces of rock)
1) Weathering/Erosion/Deposition
2) Cements or compacts (lithification)
e.g. sandstone, shale, conglomerate
2) Non Clastic
1) Evaporation (evaporites) e.g. halite
2) Organic e.g. coal (bioclastic)
METAMORPHIC ROCKS - A rock changed from any other rock. Form by: 1) Heat (marble) 2) Pressure (slate, schist, gneiss)
Minerals recrystallize – no melting!!!!
• Parent Rock → Metamorphic Rock
Examples:
• Sandstone → Quartzite
• Limestone → Marble
• Shale → Slate
WEATHERING
Weathering is simply the chemical and/or physical breakdown of a rock material--weathering involves specific
processes acting on rock materials at or near the surface of the Earth
• Weathering
• In other rocks, minerals may slowly dissolve.
• Eventually the surface of ALL rocks crumbles, or weathers.
Types of Weathering
• Physical Weathering( mechanical)
• Chemical Weathering (decomposition)
•
Types of Weathering
• Physical Weathering( mechanical)
– Takes place when rock is split or broken into smaller pieces of the same material without changing its
composition.
Example: Breaking of a rock cliff into boulders and pebbles
Common weathering processes:
– Frost action
– Wetting and drying
– Action of plants and animals
– Loss of overlying rock and soil
• Chemical (decomposition)
– takes place when the rock’s minerals are changed into different substances.
– Water and water vapor are important agents of chemical weathering.
Example: Formation of clay minerals from feldspar
• Types of Weathering
• The two processes of weathering, mechanical and chemical seldom occur alone!
• Since water vapor is present in the air everywhere means that chemical weathering occurs everywhere.
The chemical reaction of water with other substances is called hydrolysis.
The chemical reaction of oxygen with other substances is called oxidation.
CONTINENTAL DRIFT
• Alfred Wegner was one of several people who thought the continents looked like they fit together, so he proposed
the continental drift theory in 1912. Wegner was a meteorologist and astronomer so needless to say other
scientists thought he was out of his field of study.
• His studies concluded that at one time all the continents were joined together in one land mass called Pangaea.
1. Laurasia was the name given to the northern part of Pangaea
2. Gondwanaland was the name given to the southern part of Pangaea
Wegner had 5 pieces of evidence to prove his continental drift theory:
1, PUZZLE PIECES 2. FOSSIL EVIDENCE 3. ROCK EVIDENCE 4. GLACIER EVIDENCE 5. CLIMATE EVIDENCE