Questions tagged [earth]

Earth is the planet on which we live, the 3rd planet from the Sun. Questions using this tag should be about Earth the planet and not Earth-like planets nor earth, as in dirt or soil.

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Seismic Waves to earthquake position

If you would have the geographical positions of a few seismometers, the time of arrival of p-wave and s-wave, their velocity and depth of the focus under the surface. How would you determine the exact ...
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Does the earth’s rotational angular velocity change?

This is what is written in The Feynman Lectures on Physics, Vol. 1 (ch.5) We now believe that, for various reasons, some days are longer than others, some days are shorter, and on the average the ...
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Is the diameter of earth's north pole similar to the south? (Think axis of rotation+ axis of precession)

Earth is an oblate spheroid, not a sphere, since it's rotation around the axis causes it to bulge along the equator. Is it teally a symetric oblate spheroid though, or also not even that? To explain: ...
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Why is the time difference of equal tide states not 50 minute if one lunar day is 24 hour and 50 minutes?

I do understand that tidal forces are caused by de difference of gravitational force between both opposite points of the earth where a bulge is formed. I do understand that a lunar day is ruffle 24 ...
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1 answer
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Are there any types of winds or waves that are produced just by Earth's rotation?

Are there any types of wind or waves caused/produced only and exclusively by Earth's rotation? Not influenced by Earth rotation, but produced solely by it? In the case of waves, are Rossby waves 1 and ...
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Difference between Earth's surface area seen from ISS and the theoretical area if light refraction is neglected

What is the difference between Earth's surface area seen from ISS and the theoretical area if light refraction is neglected? I watched a video telling that it is not possible to know why a great ...
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1 answer
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If the Earth and the Moon were smaller, would moon tides be more or less intense?

If the Earth and Moon were smaller (and everything on them too, but keeping the same average density and the same "relative" distances, I mean... the same proportions!), would the tides ...
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1 answer
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Munroe-Question: Moving the Earth to Reduce Solar Radiation?

Rep Gohmert asked one of the funnier questions in Congress about a year ago --- could the US forestry service move the orbit of the earth? In the best tradition of Randall Munroe's "What If?"...
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Why is climate change triggering faster rotation?

On July the 29th 2022, the Earth finished its rotation about 1.5 milliseconds earlier than the entire 24 hours. Scientists link this to climate change, saying that a possible reason could be due to ...
4 votes
3 answers
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How would it be possible to measure the day's length for the past?

According to this recent article [1], Earth spins faster now than in the past, switching its trend. Besides the main focus of the above-mentioned article, what captured my attention was the knowledge ...
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What effects would a substance as hot as the sun have on its surroundings on Earth? [closed]

If you had an object, about the size of an adult human, that was as hot as the surface of the sun that somehow doesn't cool down, what effect would it have on its surroundings? Would it just vapourise ...
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Why is the slowest point of Earth's rotation in the middle of the year?

The following image is taken from Wikipedia's article on the leap second. Why is the slowest point each year in the middle of the year around July? Does being further from the Sun cause the Earth's ...
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"Earth spinning faster will break GPS and atomic clocks".. Umm, how?

Since it's just come out that Earth is apparently spinning about a milliscecond and a half faster.. I see a bunch of "articles" claiming this will.. somehow.. break atomic clocks and make ...
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1 answer
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A new way of travel or not? [duplicate]

What if you somehow go up straight into sky (assuming that you go up without any displacement in any other direction), would you land on the same spot from where you went up? If not, where could you ...
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Relation between albedo and Stefan-Boltzmann for the Earth's thermal radiation

According to the Wikipedia article on the solar constant, the earth is emitting an average $P/A=340 W/m^2$ of heat radiation, based on the argument that the earth's surface (sphere) is 4 times its ...
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Does dusk really remain for a shorter period of time at the equator?

It is said that the dusk remains for shorter time at equator than the poles. Because, the equator rotates faster than poles. But it is also true that time is the same in every latitude, and if it's ...
5 votes
2 answers
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How much solar irradiance do clouds block from reaching the Earth's surface?

Consider a fixed point in the Milankovich cycle and the solar cycle, a fixed Earth-Sun distance, and a fixed horizontal location on Earth, and assume that the Sun is at the zenith for that location. ...
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Does the perceived curvature of the earth's horizon subjectively underestimate the vastness of earth's actual curvature? [closed]

When one is standing on a beach and looks out onto the horizon, including peripherally and/or turning one's head from side to side, the horizon certainly appears curved to me. And yet the sheer size ...
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Would obliquity and precessional changes of Earth affect the accuracy of GPS-based measurement of tectonic movements?

The rate and direction of tectonic movements can be measured by comparing the coordinates of the same GPS receiver over time. The coordinates are obtained using trilateration. All materials I could ...
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Why do seismic P waves convert to S waves at an interface?

Why does a P wave refract and become an S wave when it hits an interface? What is the mechanism behind this? If P waves are longitudinal and S waves are transverse, how can this change occur?
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3 answers
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Why is it said that gravity is weaker at the equator due to centrifugal force? [duplicate]

Gravity would only be weaker at the equator if mass is not the only thing that produces gravity or if there is dense enough matter near, or at, the center to offset the additional volume of mass that ...
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How is the thermopause defined?

Wikipedia defines the thermopause to be "the atmospheric boundary of Earth ... below [which] the atmosphere is ... active on the insolation [i.e. incoming solar radiation] received." I don't ...
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How does the moon affect the position of zero gravity in the Earth?

I am interested in the position of the point of zero gravity within the Earth as a function of the gravity of the moon. Take the example of the moonless Earth. The position of zero gravity would be ...
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Why do Greenhouse Gases absorb heavily in certain wavelengths? [closed]

What molecular properties make greenhouse gases absorb and reemit primarily IR radiation? That is, why are CO2, H2O and NO2 all greenhouse gases (GHGs), but others (such as helium and neon) aren't? ...
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What is the minimum size of an object to cast a shadow on the entire Earth?

When I fly up(don't ask me how), I see how my Sun's shadow on Earth is getting bigger but dimmer as the Sun's light is reflected from other objects. As I flew higher and higher in the direction of the ...
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Could an artificial ring system around the earth produce a net-positive effect on climate change? [closed]

The greenhouse effect as I understand it is because sunlight hits the Earth, and is re-radiated as infrared heat, which is then trapped by greenhouse gasses in the atmosphere, like CO2 and Methane. So ...
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What percentage of neutrinos does the earth absorb?

Assuming a neutrino beam is directed from a point on the surface of the earth to its antipode, what percentage of neutrinos will emerge on the other side?
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Would a Magnetic Polar Shift change the location of the Earth's Axis, and thus change the locations of the continents

Did a Magnetic Polar Shift cause the sahara forest to become a desert, because it shifted the location of Africa? Will it cause the continents to shift closer or farther from the equator, causing ...
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2 answers
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Can I argue that the Earth's surface is an inertial reference to explain why we can't feel it's rotation? [duplicate]

Passengers on a plane cannot feel the plane move when it's at cruise speed. Can the same reasoning be extended to earth's rotation to explain why we cannot feel it rotate even though it's rotating at ...
2 votes
2 answers
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Is there any clear and concrete proof that says the Earth is rotating and orbiting? [duplicate]

As the title states, I am wondering if there exists a clear and concrete proof that proves that the earth is revolving around the sun on an orbit, and proves that the sun is not revolving around the ...
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Earth is spiraling away from Sun at rate of 1.5cm per year due to mass loss of Sun? How it was calculated? [closed]

My physics teacher asked if we could calculate the rate at which Earth moves away from the Sun due to the mass loss of the Sun. It's very sensible for me to understand that Earth is spiraling away ...
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Earth colliding into planet-sized object faster than speed of light [duplicate]

Imagine the following scenario: Earth is travelling in one direction at just over half the speed of light Another planet-sized object is traveling in the opposite direction towards Earth, also at ...
1 vote
2 answers
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Does the Milky Way have any impact on Earth?

Does which galaxy we are in (Milky Way) have any impact on Sun/Earth? What I mean is: suppose our solar system was instantly teleported into a different galaxy (eg Andromeda). Apart from the stars ...
3 votes
1 answer
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Using the sky and ground as a battery

Since there is a voltage difference between the ground and sky, shouldn't I theoretically be able to light a bulb by connecting one terminal to the ground and raising the other one to the sky (via a ...
1 vote
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Would a gyroscope have solved the longitude problem?

So I was thinking about the longitude problem, which was the problem of determining the longitude at sea. It caused great problems in sea navigation. See: https://en.wikipedia.org/wiki/Longitude#...
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What would happen if the Earth rotated at the rate required to achieve orbit at its radius? I.e ~7k m/s instead of ~460 m/s

To achieve a circular orbit, you need to have a velocity of $$v = \sqrt{Gm/r}$$ which is about 7 km/s at the Earth’s radius, but the Earth’s rotational speed is only about 460 m/s (by taking the ...
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Is the constancy of earth rotation speed the only reason why don't feel the rotation of earth? [duplicate]

i searched the reason of why we don't feel the rotation of earth about its axis but i found the reason is the constancy of its rotation speed ( the rate of rotation velocity is zero )but i find a ...
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1 answer
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Temperature and latitude

Currently I read this excerpt on a school power point that stated the following: " The sun is closer to the equator than the poles. Therefore the sun’s rays have less distance to travel to the ...
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Calculate the radio of the earth with a stick like Eratosthenes [duplicate]

I read about how to calculate the radius of the earth like Eratosthenes, but they often said that I should measure the shadow of a stick (usually is a stick) at the time when the solar noon occurs in ...
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NASA's explanation on tidal acceleration

I've found an animation in NASA's website, illustrating tidal acceleration effect between the moon and earth. It's the forth animation from the top in this page: https://moon.nasa.gov/moon-in-motion/...
1 vote
1 answer
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What's responsible for the earth to rotate and for the objects on it to rotate with it? [duplicate]

Three questions arose to me: The first is what is responsible for the earth spinning? Is this just newton's first law in action - having been formed out of the material in the cluster of clouds after ...
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Does Earth's electromagnetic field rotate with Earth?

I find sources saying that Earth's magnetic field rotates with Earth, but there are few sources saying that the electromagnetic field rotates with Earth. I realize the question may have a complicated ...
1 vote
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How did Al-Biruni know the height of a hill?

I knew of Eratosthenes famous experiment for determining the size of the Earth, but a recent question led me to read about another method by Al-Biruni. Like Eratosthenes' method, it required two ...
10 votes
2 answers
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How did they know the radius of the earth in ancient times?

We've all heard how in ancient times they determined that the earth was round, and were able to calculate its radius based on the measured shadows of two separate sticks in the ground at noon. I am ...
1 vote
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How much should I dig a hole to set a post?

I need your help to solve this problem We suppose that we have a post pulled by $N=4$ barbed wires separated a distance $dh = 30 \text cm$, and that each wire pulls with a force of $F=300\text N$ . ...
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Ideas for levitation using Earth's magnetic field and mu-metal [closed]

I'm not sure the idea works or not. Please answer it and its reason. As shown in Figure 1, when the ASTM A753 Alloy2 magnetic shielding alloy is exposed to an external magnetic field, the applied ...
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1 answer
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Do we have a "good" model for the temperature of the Earth's crust/mantle/core measured from the center of the earth?

Is there a "good" function $f$ that models the temperature of the Earth's crust/mantle/core measured $r$ miles from the center of the earth? By good, I mean a function that strikes a nice ...
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Distance between two points on Earth (arc length) doesn't increase with altitude (radius) according to GPS

Consider the following example: Point A has coordinates 45 lat, 0 long. Point B has coordinates 45 lat, 2 long. Both points are 5000 ft above sea level. The distance between them is X. Point C has ...
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2 answers
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What is the connection between Oort clouds and dark matter and dark energy? [closed]

I have a research assignment that I can't seem to find much info about, because it's not a very discussed or well theorized topic which is what is the connection between Oort clouds and dark matter ...
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Building orientation - how come both summer and winter solstice used for a facade?

I am planning to build a shed atop my terrace. I was analyzing the sun path to determine the overhang length, facade height etc, but got stuck with a conflict as below. The summer sun's location peaks ...

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