Geology Final
Since its creation, the universe has been expanding for
13.8 billion years and recent observations suggest the rate of this expansion is increasing.
What is each beam of light?
a unique mixture of wavelengths that combine across the spectrum to make the color we see.
Geoscientists use the geological time scale to...
assign relative age names to events and rocks, separating major events in Earth's history based on significant changes as recorded in rocks and fossils.
Vesto Slipher and Edwin Hubble
examined galaxies both near and far and found that almost all galaxies outside of our galaxy are moving away from each other, and us. - Because the light wavelengths of receding objects are extended, visible light is shifted toward the red end of the spectrum, called a redshift.
What is the Doppler effect is used on?
light emitted from stars and galaxies to determine their speed and direction of travel.
What do Astronomers think the big bang created?
lighter elements, mostly hydrogen and smaller amounts of elements helium, lithium, and beryllium. - Another process must be responsible for creating the other 90 heavier elements.
The Earth and Moon are tidally locked
meaning that as the Moon orbits, one side always faces the Earth and the opposite side is not visible to us. - Also and most importantly, the chemical compositions of the Earth and Moon show nearly identical isotope ratios and volatile content.
Spectroscopy shows that the Sun is
mostly made of hydrogen and helium.
The Hadean Eon
named after the Greek god and ruler of the underworld Hades - is the oldest eon and dates from 4.5-4.0 billion years ago. -Earth's earliest history, during which the planet was characterized by a partially molten surface, volcanism, and asteroid impacts. -Several mechanisms made the newly forming Earth incredibly hot: gravitational compression, radioactive decay, and asteroid impacts.
The giant phase in a star's life
occurs when the star runs out of hydrogen for fusion. If a star is large enough, it has sufficient heat and pressure to start fusing helium into heavier elements. -This style of fusion is more energetic and the higher energy and temperature expand the star to a larger size and brightness.
Spectra is the plural for
spectrum which is a particular wavelength from the electromagnetic spectrum.
The XXVIth General Assembly of the International Astronomical Union (IAU)
stripped Pluto of planetary status in 2006 because scientists discovered an object more massive than Pluto, which they named Eris. - The IAU decided against including Eris as a planet, and therefore, excluded Pluto as well.
An example of doppler effect
the same process that changes the pitch of the sound of an approaching car or ambulance from high to low as it passes.
What did Jupiter's massive gravity further shape?
the solar system and growth of the inner rocky planets. - As the nebula started to coalesce into planets, Jupiter's gravity accelerated the movement of nearby materials, generating destructive collisions rather than constructively gluing material together. - These collisions created the asteroid belt, an unfinished planet, located between Mars and Jupiter.
What do both rocky and gaseous planets have in similar?
- A similar growth model - Particles of dust, floating in the disc were attracted to each other by static charges and eventually, gravity. As the clumps of dust became bigger, they interacted with each other—colliding, sticking, and forming proto-planets. - The planets continued to grow over the course of many thousands or millions of years, as material from the protoplanetary disc was added. - Both rocky and gaseous planets started with a solid core.
What is the main phase of a star's life?
- Fusion -a star turns hydrogen into helium. Since most stars contain plentiful amounts of hydrogen, the main phase may last billions of years, during which their size and energy output remains relatively steady.
What are neutron stars?
- Larger stars may explode in a supernova that packs their mass even tighter to become neutron stars. - Neutron stars are so dense that protons combine with electrons to form neutrons.
The Doppler effect
- When an object emits waves, such as light or sound, while moving toward an observer, the wavelengths get compressed. In sound, this results in a shift to a higher pitch. - When an object moves away from an observer, the wavelengths are extended, producing a lower pitched sound.
What are the 3 criteria of the definition of a planet based on the IAU?
1) enough mass to have gravitational forces that force it to be rounded. 2) not massive enough to create fusion, and 3) large enough to be in a cleared orbit, free of other planetesimals that should have been incorporated at the time the planet formed. - Pluto passed the first two parts of the definition, but not the third. - Pluto and Eris are currently classified as dwarf planets.
the most reliable record for early life, the microfossil record, starts at..
3.5 billion years ago
There is possibly even evidence of life existing over...
4.0 billion yrs ago
how much history do we have of Earth?
4.6 billion
A Fusion example
An element such as hydrogen combines or fuses with other hydrogen atoms in the core of a star to become a new element, in this case, helium. - Another product of this process is energy, such as solar radiation that leaves the Sun and comes to the Earth as light and heat.
Cosmic radiation was accidentally discovered by
Arno Penzias and Robert Woodrow Wilson when they were trying to eliminate background noise from a communication satellite. - They discovered very faint traces of energy or heat that are omnipresent across the universe. - This energy was left behind from the big bang, like an echo.
temperature zones
As our solar system formed, the nebular cloud of dispersed particles developed distinct temperature zones. - Temperatures were very high close to the center, only allowing condensation of metals and silicate minerals with high melting points. -Farther from the Sun, the temperatures were lower, allowing the condensation of lighter gaseous molecules such as methane, ammonia, carbon dioxide, and water.
Another likely source of water was from space
Comets are a mixture of dust and ice, with some or most of that ice being frozen water. - Seemingly dry meteors can contain small but measurable amounts of water, usually trapped in their mineral structures. - During heavy bombardment periods later in Earth's history, its cooled surface was pummeled by comets and meteorites, which could be why so much water exists above ground.
What is the big-bang theory supported by?
Einstein's theory of general relativity, scientific evidence, grounded in empirical observations.
Why are gas giant planets different from rocky planets?
First, the original planetary nebula contained more gases and ices than metals and rocks. - There was abundant hydrogen, carbon, oxygen, nitrogen, and less silicon and iron, giving the outer planets more building material. - Second, the stronger gravitational pull of these giant planets allowed them to collect large quantities of hydrogen and helium, which could not be collected by weaker gravity of the smaller planets.
What causes the elements to condense and spin into disk shape?
Gravitational attraction or perhaps a nearby stellar explosion.
What forms a nebula?
In the tug-of-war between gravity's inward pull and fusion's outward push, gravity instantly takes over when fusion ends, with the outer gasses puffing away to form a nebula. -More massive stars do this as well but with a more energetic collapse, which starts another type of energy release mixed with element creation known as a supernova.
missing wavelengths were famously observed by
Joseph von Fraunhofer (1787-1826) in the early 1800s, but it took decades before scientists were able to relate the missing wavelengths to atmospheric filtering.
nebular hypothesis
Our solar system formed at the same time as our Sun. -the idea that a spinning cloud of dust made of mostly light elements, called a nebula, flattened into a protoplanetary disk, and became a solar system consisting of a star with orbiting planets. - The spinning nebula collected the vast majority of material in its center, which is why the sun Accounts for over 99% of the mass in our solar system.
What are the differences between rocky and gas planets?
Rocky planets built more rock on that core, while gas planets added gas and ice. - Ice giants formed later and on the furthest edges of the disc, accumulating less gas and more ice. - That is why the gas-giant planets Jupiter and Saturn are composed of mostly hydrogen and helium gas, more than 90%. - The ice giants Uranus and Neptune are composed of mostly methane ices and only about 20% hydrogen and helium gases.
What are black holes?
The largest stars collapse their mass even further, becoming objects so dense that light cannot escape their gravitational grasp. -details of the physics of what occurs in them are still up for debate.
What is the Kuiper belt?
The outermost part of the solar system. -a scattering of rocky and icy bodies. Beyond that is the Oort cloud.
What is in the center of this disk shaped nebula?
a new star is born under the force of gravity. - The spinning whirlpool concentrates material in the center, and the increasing gravitational forces collect even more mass. - Eventually, the immensely concentrated mass of material reaches a critical point of such intense heat and pressure it initiates fusion.
What is Fusion?
a nuclear reaction in which two or more nuclei, the centers of atoms, are forced together and combine creating a new larger atom. - This reaction gives off a tremendous amount of energy, usually as light and solar radiation.
What is the Oort cloud?
a zone filled with small and dispersed ice traces.
Hubble noticed that galaxies that were farther away from Earth...
also had the greater amount of redshift, and thus, the faster they are traveling away from us. The only way to reconcile this information is to deduce the universe is still expanding. Hubble's observation forms the basis of big-bang theory.
how many galaxies and solar systems does the universe have?
an infinite number
The death of a star
can range from spectacular to other-worldly (see figure). - Stars like the Sun form a planetary nebula, which comes from the collapse of the star's outer layers in an event like the implosion of a building.
The origins of the universe and solar system set the
context for conceptualizing the Earth's origin and early history.
What is the separation of minerals based on?
density and the creation of the crust, mantle, and core. - The earliest Earth was chiefly molten material and would have been rounded by gravitational forces so it resembled a ball of lava floating in space.
Common spectra include...
different colors of visible light, X-rays, ultraviolet waves, microwaves, and radio waves.
What do Stars start their lives as?
elements floating in cold, spinning clouds of gas and dust known as nebulas.
The current model of stellar evolution
explains the origins of these heavier elements.
white light from the Sun
has gaps in some wavelengths. The gaps correspond to elements present in the Earth's atmosphere that act as filters for specific wavelengths.
What are White dwarfs?
hot star embers, formed by packing most of a dying star's mass into a small and dense object about the size of Earth.
Spectroscopy confirms that
hydrogen makes up about 74% of all matter in the universe
When is giant phase is predicted to happen to our Sun?
in another few billion years, growing the radius of the Sun to Earth's orbit, which will render life impossible. - The mass of a star during its main phase is the primary factor in determining how it will evolve. - If the star has enough mass and reaches a point at which the primary fusion element, such as helium, is exhausted, fusion continues using new, heavier elements.
Where are light wavelengths are created or absorbed?
inside atoms, and each wavelength signature matches a specific element.
Eventually, fusion reaches its limit as it forms..
iron and nickel. This progression explains the abundance of iron and nickel in rocky objects, like Earth, within the solar system. - At this point, any further fusion absorbs energy instead of giving it off, which is the beginning of the end of the star's life.
The asteroid belt between Mars and Jupiter
is the source of most meteorites that currently impact the Earth. - Study of asteroids and meteorites help geologist to determine the age of Earth and the composition of its core, mantle, and crust. - Jupiter's gravity may also explain Mars' smaller mass, with the larger planet consuming material as it migrated from the inner to outer edge of the solar system.
The volcanic outgassing hypothesis
origin of Earth's water is that it originated from inside the planet and emerged via tectonic processes as vapor associated with volcanic eruptions. - Since all volcanic eruptions contain some water vapor, at times more than 1% of the volume, these alone could have created Earth's surface water.
The main topics studied in Earth history
paleogeography, paleontology, and paleoecology and paleoclimatology
giant-impact hypothesis
proposes a body about half of Earth's size must have shared at least parts of Earth's orbit and collided with it, resulting in a violent mixing and scattering of material from both objects. - Both bodies would be composed of a combination of materials, with more of the lower density splatter coalescing into the Moon. - This may explain why the Earth has a higher density and thicker core than the Moon.
Applying Spectroscopy to light from distant stars
scientists can calculate the abundance of elements in a specific star and visible universe as a whole. -can be used as an interstellar speedometer.
Apollo missions returned from the Moon with rocks...
that allowed scientists to conduct very precise comparisons between Moon and Earth rocks. - Other bodies in the solar system and meteorites do not share the same degree of similarity and show much higher variability. -If the Moon and Earth formed together, this would explain why they are so chemically similar.
What is a supernova?
the collapse of the core suddenly halts, creating a massive outward-propagating shock wave. - A supernova is the most energetic explosion in the universe short of the big bang. - The energy release is so significant the ensuing fusion can make every element up through uranium.
What can the death of the star can result in?
the creation of white dwarfs, neutron stars, or black holes. - Following their deaths, stars like the Sun turn into white dwarfs.
What formed solid slabs of early crust?
the high melting-point minerals
What did temperature differentiation result in?
the inner four planets of the solar system becoming rocky, and the outer four planets becoming gas giants.
What is Spectroscopy?
the investigation and measurement of spectra produced when materials interacts with or emits electromagnetic radiation.
differentiated the Earth from a homogenous planet into a heterogeneous one
the planet becoming layers of felsic crust, mafic crust, ultramafic mantle, and iron and nickel core.
big-bang theory proposes
the universe was formed from an infinitely dense and hot core of material. The bang in the title suggests there was an explosive, outward expansion of all matter and space that created atoms.
Explanations for the origin of Earth's water include...
volcanic outgassing, comets, and meteorites
The Kuiper belt and Oort cloud is where
where most comets form and continue to orbit, and objects found here have relatively irregular orbits compared to the rest of the solar system. Pluto, formerly the ninth planet, is located in this region of space.
