39
votes
Accepted
Why is Earth's age given by dating meteorites rather than its own rocks?
Some background:
We are able to determine the age of certain rocks and minerals using measurements of radioactive and radiogenic isotopes of certain elements. The most common are U-Th-Pb, Rb-Sr and ...
- 22.2k
22
votes
Could an icy/extremely-cold asteroid/comet ever strike and cool the Earth?
Could an icy/extremely-cold asteroid/comet ever strike and cool the Earth?
No.
The smallest possible velocity is about 11 km/s velocity, and that would require a near miracle. For that to happen, the ...
- 20.5k
21
votes
Could an icy/extremely-cold asteroid/comet ever strike and cool the Earth?
I'm gonna sail against the wind and say "yes", indirectly.
Although you don't need a cold asteroid, a "normal" one would suffice. When striking the Earth, asteroids eject a large ...
- 5,793
18
votes
Why is Earth's age given by dating meteorites rather than its own rocks?
The answers that have been provided are correct but they're omitting the fundamental issue that explains why they are correct:
When you date a rock you get the point that it solidified, not the point ...
- 353
18
votes
Accepted
Which theory is stronger, that iron came from outside or was formed within earth?
The only elements that were formed on Earth are those produced by radioactive decay. There are four natural decay chains that start with transuranic elements and none terminate in iron; neither do the ...
- 465
14
votes
Can a cosmic impact break Earth's crust in large area exposing the magma ocean?
Let me first correct a small misconception. Where you are talking about 'the magma ocean', you are implying that one exists. This is in fact false. There is no 'magma ocean' in the Earth at the moment ...
- 22.2k
13
votes
Could an icy/extremely-cold asteroid/comet ever strike and cool the Earth?
No, it's not possible to cool the Earth with an asteroid impact.
The mass of any asteroid that could hit the Earth is far too small to be a heat sink. The asteroid that killed the dinosaurs had a ...
- 11.1k
12
votes
Accepted
Water on Mars and Earth
If water on Earth came from meteorites, why doesn't Mars have substantial water?
First off, that's a conjecture regarding the origin of the Earth's water rather than a known fact. A few times a year ...
- 20.5k
12
votes
Accepted
Why don't iron meteorites on Mars rust or oxidize? Why are they shiny?
tl;dr: Compared to Earth, the atmosphere on Mars is very thin; in addition, it contains much less of oxygen and water (i.e., is very dry). It is much colder there. These conditions may slow down ...
- 596
12
votes
Could an icy/extremely-cold asteroid/comet ever strike and cool the Earth?
For your purpose (energy in the entire system) it doesn't matter if the asteroid lands gently or not because energy is conserved: If the asteroid slows through some kind of atmospheric braking, then ...
- 291
11
votes
Which theory is stronger, that iron came from outside or was formed within earth?
All the material that eventually formed our solar system is essentially recycled star dust. All iron on Earth was produced by large stars that existed before our Sun formed: the iron was created ...
- 12.7k
8
votes
Accepted
Could diamonds be formed from coal?
Craters actually can be identified by formation of high-pressure materials such as diamonds or stishovites and coesites (varieties of shocked quartz). A good example of this is the Popigai crater in ...
- 519
8
votes
Accepted
Why is Michigan Geology Circular?
A bedrock geology map will not show surficial deposits such as glacial tills, river sediments, and lake deposits. Bedrock maps have to be constructed using exposed bedrock, borehole data, and roadcuts....
- 2,753
6
votes
Why is Earth's age given by dating meteorites rather than its own rocks?
Simple enough, see the meteorites formed alongside the planet, however, since the planet was pretty much a molten soup you can't date it properly, because we can only date it after it cooled down. ...
- 59
6
votes
Which theory is stronger, that iron came from outside or was formed within earth?
I believe the element iron (Fe) is formed by stellar nucleosynthesis.
stellar nucleosynthesis:
it's a process of continuous fusion of the star element to reach heavier and heavier elements. starting ...
- 3,780
6
votes
Are craters on Earth covered by vegetation?
No, there are nowhere near this many craters on earth.
I think you're asking if there are lots of craters on earth too, but they're hard to see because of vegetation and the oceans. The answer is 'no'...
- 10.8k
6
votes
Are craters on Earth covered by vegetation?
Without water there would be no multi-billion year history of plate tectonics, no glacial action, and no fluvial erosion, so the Earth would look unrecognizably primitive. But we have an atmosphere, ...
- 14.1k
6
votes
Which theory is stronger, that iron came from outside or was formed within earth?
Somewhat more from volcanic activity than meteor impacts, but both are important.
The Earth has an iron-nickel ($\ce{Fe}$-$\ce{Ni}$) core that originates from Earth's formation out of the collision ...
- 1,177
6
votes
Is the "Kartenhoff" meteorite real?
The story told in the movie about the meteorite is fictional. Here is a quote:
The Kartenhoff, the oldest in human possession. The very meteorite
which made this crater.
The Kartenhoff is a ...
- 17.1k
6
votes
Accepted
Is it possible to estimate the size of a meteorite from its remains?
Meteors enter the atmosphere at speeds ranging from 11 km/sec, to 72 km/sec. Those speeds are so large that if a meteorite were to hit the surface at that speed, the energy released would be more then ...
- 17.1k
5
votes
Accepted
Importance of meteorite impact craters in geology?
Impact diamonds
Yes, diamonds can form in meteorite impacts. For this several things need to happen:
A meteorite of the correct size and velocity,
The stuff it hits needs to contain carbon.
If you ...
- 22.2k
5
votes
What happens if a magnitude 13 earthquake occurs?
It can be problematic to use an earthquake magnitude scale for such purposes. To explain why, you have to look at the different scales how they were produced. The magnitude scales are normally used ...
- 685
5
votes
Are craters on Earth covered by vegetation?
Erosion (especially), viscous relaxation, uplift, crust recycling (in the long term), volcanic activity, filling of the crater with deposits, and distortion by crust deformation (eg earthquakes) are ...
- 1,177
5
votes
Accepted
Are craters on Earth covered by vegetation?
Well the oceanic crust get recycled (through subduction), the oldest being only ~200 million year old, and the average, much younger. And on continents it is not just vegetation but dynamic processes ...
- 2,361
5
votes
Which theory is stronger, that iron came from outside or was formed within earth?
So (naturally occurring) elements on earth can only come to be here in three ways.
Either they are formed here via radioactive decay.
They came via meteor.
They were already here.
As mistermarko ...
- 51
5
votes
Why are there craters on the moon?
I'd like to expand on jamesqf's answer. But first,
lit side of the moon and the dark
There are no "lit" and "dark" sides of the moon. It rotates, and whatever is dark now will be lit in two weeks ...
- 22.2k
5
votes
Water on Mars and Earth
Mars did have a significant amount of water (and atmosphere) early in its history. According to NASA, there was enough to form an ocean covering about half its surface: https://www.nasa.gov/press/...
- 1,698
5
votes
Accepted
Safest spots when an asteroid hits?
Being in a submarine in the ocean is not a good idea because if a large asteroid hits the ocean the shock wave created, and its energy, would be very large. If the submarine survives intact its ...
- 21.8k
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