What evidence tells us that Venus was repaved about 750 million years ago?
What evidence tells us that Venus was "repaved" about 750 million years ago? Venus's relatively few impact craters are distributed fairly uniformly over the entire planet, suggesting that the surface is about the same age everywhere. Crater counts suggest a surface age of about 750 million years.
How does it explain the differences between seafloor and continental crust?
How does this action explain the differences between seafloor crust and continental crust? The movements involved in plate tectonics acted like a giant conveyor belt for earths lithosphere. Mid ocean ridges occur where mantle material rises upward, creating new seafloor crust and pushing plates apart.
How could a volcanic eruption give scientists direct observations of Earth’s interior?
How could a volcanic eruption give scientists direct observations of Earth's interior? Eruptions can bring mantle xenoliths to the surface allowing scientists to study them directly.
Why are there no small craters on the surface of Venus?
Venus has more craters than we see on Earth (more erosion on Earth), but no craters smaller than about 3 km due to the effects of the atmosphere (slows them down or breaks them up before they hit the surface).
How can craters tell us about the ages of surface regions of planets?
How can craters be used to determine the age of a planet or moon? Scientists record the size and number of impact craters — and how eroded they are — to determine the ages and histories of different planetary surfaces.
What is ozone How does the absence of ozone on Venus and Mars explain why these planets lack a stratosphere?
How does the absence of ozone on Venus and Mars explain why these planets lack a stratosphere? Ozone (O3) are molecules that are particularly good at absorbing ultraviolet photons. Because earth is the only terrestrial planet with oxygen, other planets cannot have an ozone, and thus cannot have a stratosphere.
What is the difference in density between oceanic and continental crust?
Continental crust is broadly granitic in composition and, with a density of about 2.7 grams per cubic cm, is somewhat lighter than oceanic crust, which is basaltic (i.e., richer in iron and magnesium than granite) in composition and has a density of about 2.9 to 3 grams per cubic cm.
How does the density of oceanic crust differ from that of continental crust Why is this important?
Because continental crust is less dense than oceanic crust it floats higher on the mantle, just like a piece of Styrofoam floats higher on water than a piece of wood does. The mantle, oceanic crust and continental crust have different densities because they are made of different kinds of rock with different densities.
What is some evidence that Earth’s center is denser than Earth’s surface?
This suggests that the interior of the earth must be denser than the crust. There is evidence that the materials within the earth form distinct layers, each with a different density. Most of this evidence comes from observations of seismic waves, the vibrations generated by earthquakes or explosions.
What evidence helps scientists understand the composition of Earth’s internal structure?
seismic waves Scientists are able to understand Earth's interior by studying seismic waves. These are waves of energy that travel through Earth, and they move similarly to other types of waves, like sound waves, light waves, and water waves.
What keeps water frozen on Mars?
In order to keep its water, Mars would need the pressure and warmth generated by a thick blanket of a greenhouse gas such as carbon dioxide. On earth, the carbon dioxide lost to space is continually replenished by volcanism.
Which of the following is evidence for volcanic activity on Venus?
What evidence exists for active volcanoes on Venus? The presence of CO2 in the atmosphere on the surface of venus gives evidence that volcanoes are currently active and the presence of SO2 and sulfuric acid clouds.
How are craters used to estimate the age of the earth?
Crater counting is a method for estimating the age of a planet's surface based upon the assumptions that when a piece of planetary surface is new, then it has no impact craters; impact craters accumulate after that at a rate that is assumed known.
What is crater density?
crater density studies (crater counting) The establishment of the relative age of a portion of a planetary or satellite surface from the observed density of meteorite impact craters.
What is the primary cause for the differences in climate between Mars and Venus?
Despite these similar initial conditions, Venus is now too hot for life and Mars is too cold. This difference in temperatures is caused partially by the different values for energy incident on these planets. The main difference is still caused by the composition and thickness of a planets atmosphere.
What would happen to the Earth without the ozone layer?
Without the ozone layer, the Earth's surface would be sterilized by UV radiation. The breakdown of the ozone layer increases skin cancer and cataracts in humans, impairs immune systems of all animals (including humans), and interferes with phytoplankton productivity in the oceans.
Which is caused by the difference in density of oceanic and continental plates?
This difference between the density of the two crusts is essential to the movement of plates because it allows subduction to take place. Subduction is a process that is caused when the oceanic crust or sea floor to bend downward then it sinks back into the mantle due to the movement of tectonic plates.
Why oceanic crust is denser than continental crust?
Bassically the Oceanic crust is made with volcanic rocks and intrussions from the Mantle (which is more dense than the crust) and it has densities of about 2.9 grams/cubic centimeter. Continental crust is about 2.7 gr/cc, becase is made from less dense rocks as granites or limestones.
How is the density of oceanic crust and continental crust different?
Continental crust is broadly granitic in composition and, with a density of about 2.7 grams per cubic cm, is somewhat lighter than oceanic crust, which is basaltic (i.e., richer in iron and magnesium than granite) in composition and has a density of about 2.9 to 3 grams per cubic cm.
What evidence do we have to support the Earth layers being different?
There is evidence that the materials within the earth form distinct layers, each with a different density. Most of this evidence comes from observations of seismic waves, the vibrations generated by earthquakes or explosions.
How do you compare the densities of the Earth crust?
There are two main types of crust; continental crust and oceanic crust that differ in a number of ways. Continental crust is thicker than oceanic crust, averaging 20-70 km thick, compared to 5-10 km for oceanic crust. Continental crust is less dense than oceanic crust (2.7 g/cm3 vs. 3 g/cm3), and it is much older.
How do we know that Earth’s interior do not have the same composition?
Tectonic plates consist of the lithosphere, which is made up of the crust and the uppermost mantle. How do we know that Earth is not the same composition all the way through? a. Seismic waves do not arrive uniformly all over the earth.
What direct evidence do we have about the structure and composition of the Earth?
Much of what we know about the world beneath our feet comes from seismic studies. Seismic studies give us indirect evidence of the composition of the layers of the Earth by studying how waves of energy produced by earthquakes travel through the Earth. These energy waves are called seismic waves.
Is the ice on Mars drinkable?
It may only need to bring enough water to get there, and bring with it the equipment needed to filter Martian water to make it drinkable by humans. The main problem with the water found on Mars is that it's salty. Possibly just as salty as Earth's oceans.
Why is Mars red?
Well, a lot of rocks on Mars are full of iron, and when they're exposed to the great outdoors, they 'oxidize' and turn reddish – the same way an old bike left out in the yard gets all rusty. When rusty dust from those rocks gets kicked up in the atmosphere, it makes the martian sky look pink.
What evidence have astronomers accumulated that liquid water once existed in large quantities on Mars’s surface?
They found evidence that ancient hot springs once existed on the surface and sustained precipitation once fell in some areas. And they found patches of ice within some of the deeper craters. Impact craters offer a view of the interior of the red planet.
What evidence can you cite that the climate of Mars has changed?
New images of the surface of Mars provide the first direct evidence that the climate of Mars has changed during the last 100,000 years, according to Brown University geologist John Mustard. This is much earlier than previous estimates, which calculated a climate change dating back hundreds of millions of years.
How does crater density used in the relative dating of features on the moon?
How is crater density used in the relative dating feature on the moon? The greater the crater density, the longer the topographic feature must have existed.
Why does crater density vary?
All bodies in the solar system exhibit craters due to impacts from asteroids and comets. However, the number density of craters can vary greatly from body to body due to weathering processes.
What happened on the Martian surface to make these crater densities so different?
Very small secondary craters indicate that the crater has undergone very little modification since its formation. Martian craters look different from those on the Moon and Mercury because the process of ejecta emplacement is different.