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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Is sunlight like a spotlight? [closed]

It is believed that if earth would have no atmosphere then the sunlight would fall on earth like a spot light. According to this fact the sunlight on moon must fall like a spot light. Does it? Then ...
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1answer
193 views

What forces carry hovering objects around the earth with its rotation?

My questions are: a) What significant forces “carry” flying objects around with the rotation of the earth, b) How do each of those forces contribute to that “carrying”, and c) How relatively ...
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1answer
65 views

Does earths gravitational force decreases?

I feel that attractive gravitational forces on Earth is somewhat similar to attractive magnetic forces. However, because the magnet loses some of its attractive force over time, will gravitational ...
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1answer
78 views

How bright would the Earth be at night without the moon?

How bright would the Earth be at night without the moon? Specifically, how much light would reach the surface of the Earth at sea level?
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2answers
65 views

It's All About Earthquake! [closed]

All the following informations i've got are from a book.(i want to check that whether the informations are correct or not,that book isnt a science book though) There is a limit to which earth can ...
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1answer
88 views

How is it we have helium on earth?

Earth gravity isn't strong enougth to hold helium so we are loosing it constantly. If earth assembled out of space dust how come we have helium? Where did it come from?
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6answers
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Where on Earth can you find plasma?

Ok, so not that 'where on earth', like literally - 'Where on Earth'. Where on Earth, can you find matter in the 4th state, i.e. the plasma state?
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3answers
3k views

Is there evidence to support that the Earth has a molten core?

I am told the Earth has an molten core. Is this a theory or has this been proven?
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3answers
158 views

Milky Way galaxy central black hole and time contraction of life story

We know that life is almost 4 billion years old on Earth. We also know that time contracts as we approach the event horizon of the massive black hole at the center of the Milky Way galaxy. Now the ...
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1answer
219 views

What does this sentence mean?

"The acceleration of free fall on the surface of the Earth is 6 times its value on the surface of the Moon." I interpreted it as: "The acceleration of free fall due to the Earth's ...
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1answer
64 views

How did the Moon survive next to the Earth since earth and Moon came into existence?

What mechanism(s) prevented the gravitational effect of the earth on the moon from shattering the moon when it was closer to the earth than the Roche Limit some 4.5 billion years ago?
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4answers
434 views

How to measure the mass of Earth?

I was wondering how you can measure the mass of Earth. From what I find on the internet, people are using Newton's Laws. But how can you do that ? Newton's Laws are assumed to work because you know a ...
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1answer
240 views
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99 views

Why Earth is not a cuboid? [duplicate]

There must be some scientific reasons for why earth is a spheroid but what are they? If Earth would be a cuboid, Would it matter?
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3answers
157 views

Why is Earth's gravitational pull only at its center?

Why is Earth's gravitational pull only at its center? Does acceleration due to gravity remain constant wherever I go in and on the Earth?
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0answers
124 views

Variation on the “Hole through the Earth” problem

In the news recently was the announcement that the answer to the classic Newtonian mechanics question of the time it takes for a body to fall all the way through the Earth was corrected to account for ...
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2answers
324 views

Will the day/night cycle change when the poles melt?

I want to know what will happen to day and night if poles melt i think it will change but I don't know why? ^_^
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0answers
34 views

Why isn't $g$ larger on the equator? [duplicate]

I understand that at the equator, you will have maximum centripetal force acting on you, whereas if you're standing directly on the pole you will have none. But because centripetal is a resultant ...
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2answers
274 views

How do we age if we tunneled to Earth's core?

Scenario Suppose there exists an advanced technology that can hypothetically transport living humans to study the center of the Earth, as they goes deeper underground most of the Earth's mass would ...
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1answer
270 views

Why does the airflow in the mid-stratosphere of the northern hemisphere rotate FASTER than the earth?

I have been playing around with this nice visualisation and noticed that in the mid-stratosphere (P=10hPa), the airflow around the equator and south of it is in the opposite direction to the earth's ...
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1answer
227 views

Since Earth spins, would an aircraft travelling opposite to direction of Earth spin take less time? [duplicate]

Suppose we want to reach the point on earth which in relative terms is exactly on the opposite end of the sphere we call earth (I know it is not an exact sphere). We either dig vertically downwards, ...
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2answers
225 views

Does radiating heat to outer space through the atmospheric transparency window have any impact on heat loss?

I was reading this article: Passive radiative cooling below ambient air temperature under direct sunlight The authors are improving upon the age-old idea of reflecting incoming sunlight while ...
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1answer
115 views

Earth's direction in space [closed]

After watching videos about the rotation of the planets being helical and not heliocentric, I wondered, as Earth travels through space, which part of Earth is the forefront?
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1answer
779 views

What is the center of Earth's landmass? [closed]

I have read, several times, that the Great Pyramid is located at "the center of Earth's landmass". How do we define "Earth's landmass"? And once defined, how do we find the center of it?
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2answers
612 views

Could the earth have another moon?

First, to clarify: I'm not asking if perhaps there's a moon that we haven't found yet. The question is, theoretically, would the earth be able to have another stable moon in addition to the current ...
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3answers
135 views

If the Earth's atmopsphere spins with the earth due to friction, why is there no horizontal spiralling drag?

Imagine a bucket of paint with a spinning ball in it. The paint would form a spiral and would not all move in synchronous movement with the ball. To clairfy - In order for the Earth's atmosphere to ...
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1answer
106 views

Wouldn't dark matter throw off the calculation of Earth's 'light' mass and estimates of its composition?

The Cavendish experiment first determined the mass of the Earth and (arguably) the gravitational constant. However, given the ubiquitous nature of dark matter, it seems reasonable that at least some ...
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4answers
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Escape velocity from Earth

We know the escape velocity from the Earth is 11.2km/s. Isn't it the velocity required to escape from earth if we go normal to the surface of earth? i.e while we derive the formula for the escape ...
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1answer
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What happens if the Russians decide to nuke the Kola borehole?

I recently came across research on the Kola Superdeep Borehole in Russia. It's one of the world's deepest at 12 km (7.5 mi) down. If someone decided to hoist a nuclear weapon all the way down and set ...
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1answer
47 views

How would a huge ball of air look in space from outside and from inside?

If you replaced the Earth (except the atmosphere) with air and kept the pressure linear to the center (of the now non-existing Earth) while ignoring the effects this would have on gravity and leaving ...
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1answer
963 views

Mars just collided with Earth! A question of eccentricity

One of the standard theories behind the formation of our Moon is the giant impact hypothesis, according to which Earth was struck by a Mars-sized body (about $10\%$ the mass of Earth) early in its ...
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2answers
96 views

Name for Earth?

What is the proper word for 'Earth', as in 'Solar' and 'Lunar'? I cannot find this anywhere; I am guessing there is a word that starts with geo?
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2answers
225 views

Average surface temperature of Earth [duplicate]

I had a question in my school exam. Will the average surface temperature of the Earth be lower or higher, if there was no atmosphere? Now, the answer expected is "The avg temp will be lower, because ...
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2answers
93 views

Why does most of the heat transferred on Earth come from the infrared part of the electromagnetic spectrum?

Why does the most of the heat transferred on Earth come from infrared part of electromagnetic spectrum?
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1answer
222 views

Does the strength of a beam of light determine how much distance it can travel?

If I point a light torch to a cloudless, crystal clear and an absolutely pristine sky, will the light beam exit the planet and travel forever in the vacuum of space? (assuming it doesn't get perturbed ...
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1answer
336 views

How does the Earth rotate, given that the torque acting on it while revolving is zero?

I've come to understand that the torque acting on the Earth while revolving the Earth is zero. Torque is the force responsible for rotation of a body. So how does the Earth rotate?
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2answers
77 views

How does the earth do a negative work on a static body? [closed]

If a body is in rest and the earth acts with a force on it 10 N Is there a negative work done by the earth though the body doesn't move? how? does it have a common thing with potential energy?
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5answers
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If you are on Earth, are your mass and weight the same?

I was wondering how mass and weight are different so I Googled it. I found that mass is constant no matter where you are because it is the amount of matter in an object and weight changes because it's ...
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2answers
9k views

What if an asteroid the size of the moon hits earth?

Would we all perish due to excessive heat? Or would that be limited to the area near the impact while the people on the rest of the earth would die from other phenomena such as mega earthquakes, ...
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1answer
138 views

Does the Moon have rotation about its axis?

As I understand, the Moon is following Earth's curved space. If that's the case, shouldn't the Moon have no rotation if it's tidally locked, and only appear to have rotation? If the Earth suddenly ...
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5answers
3k views

Video of Earth spinning?

If the Earth is spinning or rotating at a really fast speed, why haven't we seen any videos from space of it spinning when we get a lot of photos of it?
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2answers
1k views

Why doesn't Earth's atmosphere form bands due to different rotational speeds?

If the Earth's atmosphere is rotating at the same speed as Earth, then the atmosphere must be rotating much faster at the equator than at the poles. If you spin a ball covered in oil, it will form ...
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0answers
132 views

How much time would it take for a free-falling ghost-like object to cross the entire Earth? [duplicate]

We have an object of mass $m$ which can go through matter like a ghost. It's only affected by gravity, not by any other force, so it's in free fall. At the instant $t=0$ it is at the surface of the ...
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Earth's magnetic effect on my magnet

My magnet seems to work independently of, and unaffected by, the Earth's magnetic field, yet the magnetic field of my magnet changes as I introduce some other similar magnets of varied sizes into its ...
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1answer
62 views

How can one know for one's self how big the earth is?

I want to know how big the earth is. I have heard of double sun set experiments, but it appears that you need to know you latitude, which I do not. I want to do this without using any outside ...
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1answer
160 views

How much energy would it require to send Earth to Proxima Centauri?

Assuming 100% efficiency of energy usage, and given the current estimates about the mass of known objects in our solar system, including Earth itself, and assuming no other objects are affected by ...
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1answer
174 views

How much potential fusion energy is in Earth's ocean?

Assuming the most efficient manner for extraction, and a ready supply of other necessary materials not mentioned herein, and given the current estimates about the volume of Earth's ocean, how much ...
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2answers
991 views

Infinity problem: Why is gravity $g=0$ zero at the center of Earth if according to Newton gravity formula $g=GM/R^2$? [duplicate]

It is said that value of $g=0$ at the centre of the Earth. $g$ is calculated using the formula $$ g=G*M/R^2.$$ When $R = 0$, $g$ approaches infinity. I have two ...
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If I am a light travel around Earth, what relativistic phenomenons do I have?

In school, or even in university, we are only taught Lorentz transformation in one direction. It is quite easy: $$\begin{align} t' &= \gamma \left( t - \frac{vx}{c^2} \right) \\ x' &= ...