Chapter 2 - Geology 209 - University of Calgary

Milky Way

• Cosmic structure that consists of billions of stars, several planets, nebulae, interstellar dust, gasses, and particles.

What are the characteristics of the Milky Way?

(There are seven main points)

• Part of the Local Group of Galaxies which consists of 40 structures.
• Local Group of Galaxies is part of the Virgo Supergroup.
• Spiral galaxy.
• Diameter of ~100,000 light years.
• Makes a complete rotation around its center in 230 million years.
• Lens-shaped in transverse section.
• Concentrated in its center.
• Formed 1 billion years after TBB.

What are the four arms in the Milky Way?

• Centaurus
• Sagittarius
• Cygnus-Orio
• Perseus

Solar System

• Consists of a central star, celestial bodies, and cosmic dust.

What are the characteristics of the Solar System?

• 28,000 light years from galaxy center.
• 20 light years above galactic equator.
• Part of the Cygnus-Orion arm.
• Consists of several zones; inner zone, asteroid belt, intermediate zone, outer zone.

Vesto Slipher (1914)

(There are three main points)

• Studied galaxy shift in the red-blue specter.
• Galaxies moving away from our galaxy = red-shift.
• Galaxies moving towards our galaxy = blue-shift.

Edwin Hubble (1929)

(There are three main points)

• Observed that a galaxy is receding faster with increased distance from our galaxy.
• Led to the conclusion that the Universe is expanding.
• Became possible to calculate the Universe's age.

The Big Bang Theory (TBBT/TBB)

A theory that explains the beginning of Universe expansion.

How did the beginning of Universe expansion occur?

(There are three main events)

1) Universe concentrated in small portion of space 13.7-13.8 billion years ago.

2) An explosion of colossal magnitude marked the beginning of Universe expansion.

3) 380,000 years after TBB, the Universe's temperature was ~60,000, which allowed atoms to remain stable.

How did the COBE prove TBB existence?

(There are two main points)

• Mapped the discrete fluctuations in the deepest regions of space.
• Ripples on map were interpreted as vestiges of the earliest formed galaxy superclusters in the history of the Universe.

How did the WMAP prove TBB existence?

(There are two main points)

• Reiterated measurements recorded by COBE and provided them at a higher resolution.
• Ripples on map were interpreted as vestiges of the earliest formed galaxy superclusters in the history of the Universe.

Stars

• Massive celestial bodies of quasi-spherical shape; consists of ionized gasses (H, He).

What are the characteristics of Stars?

(There are five main points)

• Radiate energy due to thermonuclear reactions in their interior (fusion).
• Radiate energy till their hydrogen reserve depletes.
• Diverse in luminosity, size, and temperature.
• Most consist of a single body.
• Contain heavier elements (oxygen, carbon, iron)

Fusion

• Two light atomic nuclei combining to form a single heavier one while releasing massive amounts of energy.

Nebulae

• Agglomerations of cosmic matter.

What are the characteristics of nebulae?

(There are three main points)

• Diverse in shape, density, composition, and size.
• Consists of H2, He, and cosmic dust.
• "Birthplace of Stars"

The Sun

The star at the center of the Solar System.

What are the characteristics of the Sun?

(There are four main points)

• Diameter of ~1,500,000km.
• Consists of 98.85% of the SS's mass.
• Is 20 million degrees.
• Consists of 73% hydrogen, 25% helium, and 2% of other elements.

Terrestrial Planets

(There are four)

• Mercury
• Venus
• Earth
• Mars

What are the characteristics of terrestrial planets?

(There are six main points)

• Closest to the Sun.
• Solid at the surface, with a rocky appearance.
• Density varies between 3.9g/cm^3 and 5.5g/cm^3.
• Not many natural satellites; the Moon, Deimos, and Phobos.
• Contain atmosphere, except Mercury.
• Iron-dominated core at the center, surrounded by two layers: mantle and crust.

Jovian Planets

(There are four)

• Jupiter
• Saturn
• Uranus
• Neptune

What are the characteristics of jovian planets?

(There are six main points)

• "Gas Giants".
• Low densities, ranging from 0.7cm^3 to 1.7g/cm^3.
• Large number of satellites.
• Atmospheres are H2 dominated, He is the subdominant.
• Inner core consists of iron silicates, ice, and ice-dominated terrain.
• Other layers are gas-dominated.

Icy Planets

• Pluto

What are the characteristics of icy planets?

(There are five main points)

• Outermost in the SS.
• One natural satellite: Charon.
• Rocky core that is iron-dominated.
• Upper layer contains mantle and crust.
• Mantle and crust consist of icy water, icy methane, and icy ammonia.

The Moon

(There are two main points)

• Earth's only natural satellite.
• Formed 4.6 billion years ago.

What are the characteristics of the Moon?

(There are five main points)

• Diameter of ~1/4 of the Earth's diameter.
• Density of 3.3g/cm^3.
• Consists of a metallic core and silicate rocks.
• Has depression areas and highland areas.
• Contains craters that resulted from impacts with meteorites.

Jupiter's Natural Satellites

• 40 satellites.
• Io, Europa, Ganymede, and Callisto*
• Io has active volcanoes.
• Europa has a rocky surface covered in a layer of water-ice, might have had life forms.
• Callisto has the highest number of impact craters.

Saturn's Natural Satellites

(There are three main points)

• 31 satellites.
• Largest is Titan, which has a N2 dominated atmosphere.
• Has volcanoes that expel frozen N2 and methane.

Asteriods

A type of celestial body that originated from collisions of smaller planetary bodies.

Ceres

(There are two main points)

• The largest asteroid.
• Diameter of 1,000km.

Comets

A type of celestial body that revolves around the sun on elongated orbits and consists of frozen gas and icy-water.

What are the characteristics of comets?

(There are two main points)

• Small rock.
• Solid appearance.

What happens to the physical state of the gasses in comets as it approaches the Sun?

1) A gaseous glowing coma forms in the anterior part from the gaseous component vaporization.

2) A small nucleus with a solid appearance remains within the coma.

3) A tail forms at the opposite end, and it opposes the Sun do to its energy.

Meteorites

• Large rock fragments from interplanetary space that entered in collision with a larger celestial body.

What are the characteristics of meteorites?

(There are two main points)

• Diverse in appearance.
• Rocky.

What are the three meteorite groups?

• Stony
• Iron
• Stony-Iron

Stony Meteorites

(There are two main points)

• Composed of silicates.
• Contain chondrules formed through the solidification of molten matter droplets.

Chondrites

• Meteorites that contain a lot of chondrules in the mass.

Achondrites

• Meteorites that have a similar chemical composition to chondrites, but lack chondrules.

Carbonaceous Chondrites

• Contains organic compounds (amino acids) that make up 5% of the meteorite mass.

Iron Meteorites

(There are two main points)

• Large-sized minerals in their mass and consist of iron-nickel alloys.
• Composed of mostly iron.

Stony-Iron Meteorites

• Composed of silicates and iron-nickel alloys in equal proportions.

What are the characteristics of space dust?

(There are three main points)

• Exists in interplanetary and interstellar space.
• Consists of small particles composed of carbon, iron, calcium, etc.
• Irregular in shape and have a max. dimension smaller than a mm.

The Solar Nebula Theory (SNT)

A theory that explains the formation of Earth as part of the SS.

Who contributed to the SNT?

(There are two main individuals)

• I. Kant in the 18th century.
• Pierre-Simon Laplace in the 18th century.

Phase I (SNT)

(There are five main ideas)

• SS formation began with a cold cloud, an agglomeration of gasses, and space dust.
• Temperature was extremely low due to an absence of an energy source.
• Chemical composition of the cloud consisted of hydrogen and helium.
• Interactions with stars or clusters near the cloud caused it to change shape and contract, and might have even rotated.
• This occurred 5 billion years ago.

Phase II (SNT)

(There are four main ideas)

• Cloud rotation became the dominant movement in this phase instead of contraction.
• Cloud flattened at two poles, and matter began to concentrate in the center.
• Particle friction produced heat which built up in the center.
• The cloud still had a low-density and low-temperature (-200).

Phase III (SNT)

(There are four main ideas)

• Particle agglomeration and gradual heating proceeded.
• Small particles in the cloud started to aggregate, forming large rocks.
• Large particles attracted smaller ones, causing swirls and irregular particle movements.
• Matter began to concentrate in the equatorial plane and concentric rings.

Phase IV (SNT)

(There are three main ideas)

• Temperature reached millions, causing a Protosun to form.
• Accretion formed protoplanets on the concentric rings.
• Matter in protoplanets collapsed due to gravity, resulted in heavier element concentration in the center.

Phase V (SNT)

(There are five main ideas)

• Happened due to the initiation of thermonuclear reactions in the Protosun.
• Caused ionization of gasses and initiated solar wind, causing a radiation flux that played a role in gas redistribution.
• Terrestrial planets could not retain lighter gasses, and therefore, pushed them beyond the asteroid belt to Jovian planets.
• Planets generated magnetic fields that prevented heavier gasses form being expelled into space.
• Did not occur in Jovian planets due to their lower temperatures.

Phase VI (SNT)

(There are two main ideas)

• Collisions occurred between planetary bodies, causing asteroids to form.
• New celestial bodies formed such as the Moon.

What evidence exists for Phase VI?

(There are two main points)

• Meteorite bombardment on the Moon.
• Meteorite composition: stony meteorites detached from mantle and crust of colliding planetary bodies, iron meteorites from cores, and stony-iron meteorites from proximity of mantle/core boundary.

What is the dominant gas in the Venus and Mars atmosphere?

CO2.

A planet in the early stages of formation is referred to as...

• Planetesimal.

Which planet has a core consisting of molten matter?

• Venus.

What is the process through which planets were formed?

• Matter Accretion.