36 votes
Accepted

How do we know the asteroids formed at the same time as earth?

what evidence do we have that the asteroids indeed formed at the same time as earth? It depends on what is your definition as "the same time". The formation of the solar system and Earth did not ...
  • 22.3k
24 votes
Accepted

What is the fastest the Earth has ever spun?

The speed of rotation of Earth is controlled by its angular momentum. And the conservation of angular momentum is a very serious law of physics (perhaps even stricter than conservation of mass). So in ...
  • 17.1k
17 votes
Accepted

How bad is geo-engineering?

The bad part about geo-engineering are the unknown unknowns, to paraphrase a certain US politician. Our climate models are wrong. All models are wrong, but some are useful.. Our models are useful, ...
  • 11.2k
14 votes
Accepted

Plate Tectonics: Is it possible to have an ocean-continent divergent boundary

The oceanic plates are themselves formed from the divergent boundary, so probably not. Even if a new rifting occurred exactly at the boundary, the result would eventually be that the ocean floor ...
  • 5,906
12 votes

How do we know the asteroids formed at the same time as earth?

The formation of a T-Tauri star spells the beginning of the end of the protoplanetary disk from which planets and asteroids can form. The end is nigh when that star ignites. The large solar winds and ...
  • 20.7k
12 votes

Would life on Earth survive without the Sun?

The answer is No, the Earth would not remain in any recognizable form without the Sun. There would still be a husk of a dead planet with a small amount of energy coming from the residual heat of ...
11 votes

How do archaeologists address time dilation when analyzing carbon dating results?

For all intents and purposes, the Earth represents one frame of reference, as @kwinkunks states. Therefore no effect. Yes the gravitational field on top of a mountain is slightly less than at sea ...
  • 3,843
11 votes

How do archaeologists address time dilation when analyzing carbon dating results?

How do archaeologists address time dilation when analyzing carbon dating results? They don't. There is NO point in doing so. Compare two hypothetical substances at the peak of Chimborazo (the highest ...
  • 20.7k
11 votes
Accepted

Will dust storms be more frequent in the future?

Most dust storms occur down-wind from areas with a lack of moisture, little vegetation, and high soil content. Vegetative roots help to keep the soil intact when there is a lack of moisture. So any ...
  • 12.7k
11 votes
Accepted

Diamond at the core of Jupiter

I would think this is questionable, though we don't have a definitive answer yet. We usually think Jupiter has a roughly solar composition, which according to the solar abundance measurments of ...
11 votes

Eclipse, Hurricanes, Earthquake....Related Events?

The occurrences of Hurricanes, Harvey, Irma, Katia and Jose, east of Mexico and a magnitude 8.1 earthquake southwest of Mexico within a few weeks of the American solar eclipse of August 21, 2017 are ...
  • 21.9k
10 votes

To what accuracy and precision do we know the volume of the Earth?

One way to approach this is to treat the Earth as an oblate ellipsoid. This would mean the errors arise from the uncertainties in the Earth's equatorial radius and the flattening. From Groten, "...
  • 20.7k
10 votes

Are old geophysics textbooks useful?

Mathematics and computer science are exact sciences. If something is discovered and known, it is not wrong. With time, there may be better or new ways of doing something, but the old stuff is still ...
  • 22.3k
9 votes

What sort of climate zones would be present if Earth was tilted like Uranus?

A paper on this topic just appeared: Multiple Climate States of Habitable Exoplanets: The Role of Obliquity and Irradiance. In case of 90° obliquity, summer and winter would appear together with day ...
  • 91
9 votes

Earth's ocean basins

Was the Earth seafloor always carved with the numerous geological features that we see today? Absolutely not. The seafloor is where plate tectonics is starts and ends. The seafloor is extremely ...
  • 20.7k
9 votes
Accepted

What color(s) would Earth be without water or life?

That's actually an interesting question. Let's try to answer it, but first let's make a few assumption. Oxygen on Earth is biogenic, so without life there would be no oxygen. However, let's assume ...
  • 22.3k
9 votes

Carbon dioxide on Mars, Venus and Earth

Firstly, Mars is farther away from the sun than Venus or Earth, so it gets less heat from the sun. Secondly, Venus & Earth are volcanically active, whereas Mars is volcanically inert. Thirdly, the ...
  • 21.9k
9 votes
Accepted

How far up do you have to go before most of the atmosphere is below you?

Roughly 5.5 km, although the exact value depends on the weather. All you need to do is to solve the hydrostatic equation and find the height at which the pressure is 50% of the height at sea level (...
  • 11.2k
9 votes

How far up do you have to go before most of the atmosphere is below you?

It turns out that the answer is a bit simpler than you think. Atmospheric pressure (neglecting small weather variations) is due to the weight of the column of air above a given point. If we divide ...
  • 91
8 votes

Why do some planets have lots of $\mathrm{N_2}$ and others none?

For Earth, Titan and Venus, I think there are continuing processes that are providing $\ce{N2}$ to the atmosphere of these planets. Concerning the Earth, there is the well documented Nitrogen cycle ...
8 votes

Geomorphology of Mountains With Wind only Erosion

You do have an earth analogue for this. The Namib Desert in Namibia has been a desert for the past 2 million years with very little precipitation. Also the Atacama Desert is hyperarid since more than ...
  • 472
8 votes

What properties must a rocky body possess in order to exhibit the magnetic dynamo?

Aside from the three requirements already mentioned, electrically conductive fluid, rotation of the planet and convection of the fluid, the main additional requirement is a seed magnetic field. There ...
  • 5,912
8 votes
Accepted

What sort of instruments do planetary geologists use to predict that there are oceans on the moons Titan and Europa?

As casey said, the satellite isn't an instrument in itself, it is a platform hosting many instruments. What you're talking about the discovery of oceans on Titan and Europa, you're referring to the ...
  • 924
8 votes

Do other terrestrial planets have "earthquakes"?

For terminology, "Earth"quakes might be replaced with "seismic activity" since earthquakes are by definition restricted to the Earth. Technically speaking the other terrestrial planets in our solar ...
  • 12.7k
8 votes

Would life on Earth survive without the Sun?

The Earth is as it currently is and has been since most of the Phanerozoic (542 Ma), the Eon of life, because of some important (not exhaustive) characteristics presented here, being: its inclination ...
  • 2,633
8 votes

How bad is geo-engineering?

Seconding eveything that @gerrit mentioned. Additionally, another major problem with geo-engineering is that once we've started these processes and essentially borrowed time to offset mitigation ...

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