Unit 3 Flashcards
What characteristic is used to differentiate gas planets from terrestrial planets?
Based on its density
What elements are common in rocky planets?
Silicon, Oxygen, Aluminum, Mg, Sulfur, and Iron
What is the most abundant rock type?
BASALT
Do planets close to the Sun experience more or less bombardments?
The closer they are the more often it will be bombarded, because of its massive gravitational pull
Which model is favoured for how the Moon originated?
The giant impact hypothesis, Earth’s spin and the Moon’s orbit have similar orientations etc.
Why was the Fission hypothesis rejected?
Would have required that Earth rotated once every 2.5 hours rather than once every 24 hours
Why was the Condensation hypothesis rejected?
They didn’t have the same chemical composition AND the Moon doesn’t orbit Earth exactly on an equatorial plane
Why was the Capture hypothesis rejected?
Probability for the exact gravitational and dynamic conditions needed for an object the size of the Moon to fall into orbit about Earth is unlikely. Chemical were so similar between the 2 that there had to be some genetic relationship. Lastly all computer model attempts failed
What is the Giant Impact Hypothesis?
A planet that was somewhat smaller then Earth, gave Earth a glancing blow sometime about 4.5 billion years ago
What is Theia?
A hypothetical planet smaller than Earth
How did the Giant Impact affect Earth’s structure?
Glancing blows gave an increased angular momentum, metal core dropped into earth giving it a large metal core and high density
What materials make up the Moon and why is it similar to Earth?
Molten mantle material, which formed debris, which was collected and formed into the moon, similar to Earth because some of the debris fell back on to earth
What evidence is used to support that the Moon formed as a result of a large impact?
Using the computer simulation, shows near complete mixing of Theia with Earth, and ends with a disc of material from which the Moon could form
Was the impactor (Theia) large or small?
It was roughly the size of Earth (fairly large)
What some facts about Earth? (size, density, internal zone)
Its the 5th largest planet, Densest body in the Solar System
What are the properties of the Hydrosphere and Atmosphere?
Our hydrosphere has water on the surface, a largely closed system:you neither lose nor gain water. Our atmosphere is mostly nitrogen and oxygen
What makes Earth unique among the terrestrial planets?
Its magnetic field is uniquely strong. Mercury and Mars is weak and Venus has none
Explain the role of Accretion in the formation of the Earth
Earth grew by the accretion of smaller objects, objects would have attracted others by simple gravity and eventually became an actual planet
How was Earth’s core formed?
With accretion??
What is the most common element on Earth?
IRON
What is the largest zone of the Earth?
The Mantle
How do pressure, temperature and density change as you move from the crust towards
the core?
All 3 will increase
Why does Earth have a magnetic field?
Because it has an internal ‘generator’ of electric currents
What is the evidence that supported the hypothesis of continental drift?
Observed that part of the coastline of Chile had been raised up as a result of a great earthquake. Fossils and shells were found in odd spots etc
Give an example of how you can tell the order in which rocks were formed based on their relative position
When observing a sequence of undisturbed horizontal sedimentary rocks that the layers at the bottom of the sequence are older than those at the top
How can we use radioactive elements to determine the age of a rock ?
Uranium and Thorium are used because it takes millions-billions of years for the parent to decay
How old it the Earth, its surface and the ocean floors?
Around 4.5 billion years old, and the surface a slightly younger and the ocean floors are hardly ever over 250 million years old
Describe how the Earth’s atmosphere, hydrosphere and biosphere are interconnected
Water vapour in the atmosphere started to condense and rain began. When it started raining, the hydrosphere was born. Biosphere appeared because the ocean was sheltered from the hostile atmosphere
How does Earth’s atmosphere differ from Mars and Venus?
Earth’s is dominated by mostly nitrogen while Mars and Venus contain very little amounts of nitrogen
Where did Earth’s water come from?
From comets and asteroids that pummelled into Earth
Explain two ways that biology has affected the composition of the atmosphere – how are
these changes beneficial to life?
Through photosynthesis, adding oxygen into the atmosphere AND through the removal of carbon form the atmosphere
How did Prokaryotes avoid toxic effects of the
oxygen they produced during photosynthesis?
Iron has a strong ability to absorb oxygen, so the oxygen would have quickly combined with iron, oxidized iron is insoluble in water, oxygen formed would never leave the ocean
How do we finally start to accumulate oxygen in the atmosphere and what were the effects on
biology/evolution?
Eukaryotes, used oxygen for respiration, and contributed great amounts of oxygen to the atmosphere
How is CO2 removed from the atmosphere and how does this affect Earth’s temperature?
It was combined with Calcium, as they were removed, the temperature declined
Trojan Satellite
An object that has the same orbit as another body, but doesn’t collide with that body because it’s located in a particular point on the orbit called Legrangian point
Has Earth ever had more than 1 satellite?
Yes, the moon sometimes had a partner
How do we know the Moon doesn’t have an atmosphere?
If the planet has an atmosphere, smaller meteoroids may be destroyed in that atmosphere or slowed so much they do not make craters, but we see craters of all sizes on the Moon
How do we know the Moon doesn’t have any plate tectonics?
Plate tectonics requires that the body remain hot long enough for the interior to convect and keep the crust moving. The moon, being relatively small, was not endowed with much heat to begin with, and it cooled relatively quickly
What does the study of impact craters tell us about the age of the Moon?
These craters accumulate with time. The older a surface, the more impacts it has experienced
What is the Maria and why does it only occur on the near-side?
Dark area, filled with solidified basalt lava an IDK why
Are you more likely to see small craters form the Moon or Earth?
On the Moon
If the same size meteorite hit Earth and Moon, which would have a bigger crater?
The Moon