The Big Bang Theory, Formation of the Solar System, Structure of the Sun, Discerning Earth's History, and Geologic Time Midterm study guide
The temp. of the Sun's core is about _____.
10,000,000 degrees C
Sunspots vary in a cycle that lasts about _____.
11 years
The Big Bang occurred about_____.
14 billion years ago
The main sequence stage is the _____ of a star's life cycle.
2nd stage
Scientists estimate the age of out Solar System to be _____.
4.6 billion years
When was the beginning of Precambrian time?
4.6 billion years ago
Unconformities are:
A break in the geologic record created when rock layers are eroded or sediment is not deposited for a long period of time
A Nebular Cloud is...
A collection of dust and gas from which a solar system and/or a star is born
Particles thrown off the Sun's corona that can affect Earth's magnetic field are called _____.
A coronal mass ejection
Precambrian Era
A division of time that began with the formation of Earth and makes up about 88% of Earth's history
Index Fossils:
A fossil that was widespread, but only lived for a short period of time
Mesozoic Era
A geologic interval known as the Age of Reptiles
Cambrian Period
A geologic interval that began with the first marine vertebrates including trilobites and brachiopods
One of the FINAL products of the fusion of 2 hydrogen nuclei in the Sun is always _____.
A helium nucleus
Radiometric Dating:
A method of determining the absolute age of an object by comparing the relative percentages of a radioactive parent isotope and a stable daughter isotope
What best describes Earth's first ocean?
A shallow pool that covered the entire planet
A sunspot is NOT _____.
A solar eruption
How much of the matter contained on the Solar Nebula makes up our Sun?
About 99%
When did the Paleozoic Era occur?
After Precambrian time
What is a prominence on the Sun?
An arched, glowing cloud of gas that rises above the Sun's photosphere
Radioactive Elements:
An element whose isotopes emit particles from their nucleus
When were the Sun and planets formed?
At roughly the same time
What are northern lights?
Auroras
The hottest stars are what color?
Blue
What do scientists believe was the first form of life on Earth?
Blue-green algae
The method used to determine the age of fossils in a rock layer is called:
Carbon-14 dating
The magnetic field of the Sun's corona _____.
Causes Earth to be polarized
By the en dog the Paleozoic Era, Earth's landmasses had _____.
Collided to form a supercontinent called Pangea
Which factors were important in the formation of our solar system?
Collisions + Gravity
How did natural selection favor wooly mammoths and saber-toothed tigers during the Pleistocene Epoch?
Conditions favored animals that could endure cold climate
The Sun converts matter into energy in the _____.
Core
What makes up most of the universe?
Dark energy and dark matter
What period is better known as the Age of Fish?
Devonian Period
What was the dominate life form during the Mesozoic Era?
Dinosaurs
When hydrogen nuclei fuse into helium nuclei _____.
Energy is released
What is the largest unit of geologic time called?
Era
What causes a Nebula to collapse?
Gravity
What elements make up most of the Sun's mass?
Hydrogen + Helium
During nuclear fusion in the Sun, what occurs?
Hydrogen nuclei combine to produce a helium nucleus
In a non-conformity what types of rock underlie the sedimentary rock?
Igneous + Metamorphic
What is most important about Hubble's discovery that there is a red shift in the spectra if galaxies?
It suggests that the universe is expanding.
What major event in Earth's history occurred between the Mesozoic and Cenozoic Eras?
K-T mass extinction
The Sun is part of a group of stars known as:
Main sequence stars
How does the mass extinction at the end of the Permian Period lead to an abundance of new life forms?
Many resources were available for the species that survived
Auroras are frequently seen _____.
Near the equator
Most of the Sun's energy is a result of _____.
Nuclear fusion
Are white dwarf stars OLDER or YOUNGER than main sequence stars?
Older
Are white dwarf stars OLDER or YOUNGER than red giant stars?
Older
Earth's early atmosphere continued to form when volcanic eruptions released gases in a process called _____.
Outgassing
How do Paleozoic rocks differ from Precambrian rocks?
Paleozoic rocks contain many more fossils
How is radioactive decay used to determine the absolute age of rocks?
Parent isotopes are compared to daughter isotopes
Longest geologic time span in Earth's history is _____.
Precambrian Era
Some planetesimals joined together through collisions and through the force of gravity to form larger bodies called _____.
Protoplanets
The coldest stars are what color?
Red
As the Sun begins to die, it will leave the main sequence and become a _____.
Red giant
What did Hubble discover in the 1920's?
Red shift in spectra if galaxies
When the Paleozoic Era began, Earth's landmasses were _____.
Scattered around the world
The rotating cloud of dust + gas which our solar system is thought to have formed from is called the _____.
Solar Nebula
A rotating cloud of gas + dust from which Earth's solar system formed is called _____.
Solar nebula
As the Sun begins to die, it will _____.
Swell and swallow the inner planets
Relative Age:
The age of an object in relation to the ages of other objects
1/2 life:
The amount of time it takes for half of an element to decay
Cenozoic Era
The geologic era that includes the present; the geologic era the is the Age of Mammals; a division of time that began after the most recent extinction 65 million years ago
What do scientists need to know before they can use radioactive decay to determine absolute age?
The half life of the radioactive isotope
The Law of Superposition states:
The idea that a sedimentary rock layer is older than the layers above it, and younger than the layers below it, if the layers are undisturbed
The Principle of Original Horizontality:
The idea that undisturbed sedimentary rock will stay in perfect horizontal beds
What happened to Earth about 600 million years ago?
The levels of oxygen and carbon dioxide remained constant
How would you describe how our Sun was formed from a Solar Nebula?
The nebula absorbed energy, causing it to begin rotating at a high speed, The nebula became extremely hot & dense near the core, and, The nebula instantly started nuclear fusion in the core. (3 possible answers to the question)
Absolute age is:
The numeric age of an object/event often stated in years
The Law of Cross-Cutting Relationships states:
The principle that a fault or body of rock is younger than any other body rock that it cuts through
Decay rates:
The rate at which radioactive materials change from parent to daughter isotopes
The law of Superposition helps scientists determine:
The relative age of a layer of sedimentary rock
What happened to the hydrogen & helium that were present in Earth's early atmosphere?
They were probably blown away by solar winds
Why are Precambrian rocks difficult to study?
Very few rocks existed from Precambrian time or tectonic activity has altered the original order of rock layers
What is the position of our solar system in out galaxy?
We are located on the Sagittarius Arm toward the edge of the galaxy
Dark energy is...
a force that opposes gravity
Cosmic background radiation is...
a remnant of the Big Bang
A solar flare is a _____.
a sudden outward eruption of electrically charged particials
The temperature of cosmic background radiation is _____.
almost absolute zero
The Solar System is...
an area described as the Sun, all the planets, and other bodies that travel around the sun
An aurora is a _____.
colored light produced when charged particles from solar wind react with Earth's upper atmosphere
A sunspot is _____.
cooler, dark area of the photosphere, with a strong magnetic field
A coronal mass ejection is _____.
coronal gas thrown into space by the Sun
The early oceans became salty when _____.
dissolved solids were carried from land into the oceans
Sudden disturbances in Earth's magnetic fiels are called _____.
geomagnetic storms
3rd stage of a star:
giant/supergiant
During fusion, what is given off as a result of the final step?
heat + light
A prominence is a _____.
loop of incandescent gas that extends above the photosphere
Dark matter is...
material that does not give off light but has detectable gravity
What are parts of Sun's atmosphere?
photosphere + chromosphere
Auroras form when charged particles from the solar wind _____.
react with particles in Earth's atmosphere
A star that is moving away from Earth has a spectrum that is ______.
shifted toward red
Astronomers believe that cosmic background radiation was formed ______.
shortly after the Big Bang
The Milky Way is...
the galaxy that our solar system belongs to
The Big Bang Theory is...
the hypothesis that all matter and energy in the universe was contained in an extremely small volume that exploded and began expanding in all directions
The order of rock layers reveals:
the relative age for each layer
Cosmology is...
the study of the origin, structure, and evolution of the universe
The Spiral Arm is...
where our Solar System is located on this part of the Galaxy
