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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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
68 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
45 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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2answers
40 views

Which will collide first, the moon and Earth, or Sun and Earth?

As time progresses, which scenario will happen first? The moon colliding with Earth, or the Earth colliding with the Sun? I figure the Moon and Earth will happen first, based on proximity, but the sun ...
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1answer
58 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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1answer
129 views

How the Moon causes the tides?

I am considering the following question but I con't quite figure it out... I have looked up differential gravity but I cannot derive the equation for the effect on earth, and I haven't found any ...
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2answers
42 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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0answers
33 views

Supposed navigation from Sagittarius to Earth [closed]

Presume you are on a planet in the Sagittarius and want to set course for Earth. What would the coordinates be? I have looked all over the internet without any luck so I hope for the best.
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5answers
151 views

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
981 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
45 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 ...
0
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1answer
166 views

Why does Earth behave like Natural Bar Magnet?

What is the reason for the Earth to behave like a bar magnet and have poles (North and South poles)?
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1answer
83 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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6answers
4k views

If the gravity at the center of the Earth is zero, why are heavy elements like iron there?

If gravity is zero at the center of the earth, why is there a core of heavy elements, such as iron? Alternate question for the opposite hypothesis: If gravity is greatest at the center of the ...
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5answers
2k 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?
22
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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 ...
2
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0answers
72 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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0answers
22 views

Chemical composition and structure of Earth's inner layers?

How exactly do scientists determine the chemical composition and structure of Earth's inner layers, for example that the outercore is composed of liquid iron and nickel, and that the mantle is is ...
0
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1answer
59 views

What is the longitudinal difference between the sub­solar point and the magnetic poles at time $t$ (hours)?

I'm trying to convert geomagnetic coordinate to geographic, but there are some steps in the paper which I'm reading, that I don't understand. I have the geomagnetic latitude centered around the ...
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0answers
19 views

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
42 views

Can we get energy from the Earth's rotation?

Is there any way to harvest large amounts of energy from the Earth's rotation?
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1answer
46 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 ...
4
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1answer
2k views

What if the earth's core goes cold?

What effects would occur if the earth's core goes cold? Would the planet stay liveable after this happens?
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1answer
67 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 ...
2
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1answer
43 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 ...
2
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2answers
128 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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0answers
39 views

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' &= ...
3
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1answer
120 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 ...
29
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4answers
7k views

Why is a new moon not the same as a solar eclipse?

Forgive the elementary nature of this question: Because a new moon occurs when the moon is positioned between the earth and sun, doesn't this also mean that somewhere on the Earth, a solar eclipse ...
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1answer
59 views

Where did earth's electric charge come from?

I get between .7 and 1.3 volts out of a 20 foot tree depending on the weather. I understand this is "telluric" electricity with pretty low amperage. Where is this charge coming from? The sun, right? ...
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2answers
74 views

If earth's magnetic field disappeared, would cosmic radiation lead to increased radioactivity?

This is about the effect of cosmic radiation on earth. Is it the type of radiation that could make things radioactive? So if earth's magnetic field weakened considerably (such as could happen if it ...
2
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3answers
47 views

Solar plants and energy conservation

I'd like to apologise if this question is stupid or if it was asked ten thousand times - I haven't found an answer to it. Quite possibly due to mediocre English or abominable knowledge of physics. ...
0
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4answers
282 views

Why is there no gravity in the center of a celestial body, yet there is gravity on the surface? [duplicate]

I've heard few explanations, but none in good detail that make it clear to those with less mathematical knowledge on the equations of complex physics. I would like to think that since you are on the ...
0
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1answer
35 views

How is north defined for any point on the surface of the earth?

While studying about terrestrial magnetism, references were made to north direction, and the geographic meridian and later magnetic meridian defined using that. But what is actually the north ...
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0answers
63 views

Could we have a black hole on Earth? [duplicate]

There was once a Far Side cartoon in which a black hole had opened in someone's living room and was sucking the furniture, people, pets, etc to the middle of the room. It was a funny picture, but ...
2
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2answers
71 views

Is It Possible To Move The Earth In A Direction? [duplicate]

According to Newton's 3rd law, when an object moves upward, the Earth moves by a very tiny factor in the opposite of the direction of the object. And when the object falls back, the earth moves back ...
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4answers
5k views

What is the scientific reason for the inclination of earth's rotation axis?

This titled position of the earths axis is known as inclination of the earths axis. The earth's rotation axis makes an angle of about 66.5 degrees with the plane of its orbit around the sun, or about ...
9
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1answer
507 views

How much does increased world population contribute to global warming?

In 1974 there where 4 billion people on earth. Now in 2013 we passed 7 billion people. So the world population is nearly doubled in 40 years. Every living human being also haves a body temperature of ...
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5answers
965 views

Is the earth expanding?

I recently saw this video on youtube: http://www.youtube.com/watch?v=oJfBSc6e7QQ and I don't know what to make of it. It seems as if the theory has enough evidence to be correct but where would all ...
0
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2answers
83 views

If earth stopped spinning how much heavier would 1kg feel [closed]

My girlfriend seems to think if the earth stops spinning we will all fall off However, she did spark my imagination, due to centripetal force things must feel lighter then they otherwise would on an ...
2
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1answer
51 views

Why is the Earth self-rotating? [duplicate]

What drives this happen? Would it be the internal energy or by an external force? I did try to Google the answer, but could not find a good one.
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1answer
44 views

Physics Riddle - Know Plant Earth [closed]

I hope it's OK to ask here, because it's pretty much as basic as physics can get. So here it is: I have a hot air balloon that can rise to any altitude I'd like, a precise watch, a sandbag, a weigh ...
30
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12answers
11k views

What is the simplest way to prove the Earth is round?

Assume you've come in contact with a tribe of people cut off from the rest of the world, or you've gone back in time several thousand years, or (more likely) you've got a numbskull cousin. How would ...
16
votes
3answers
1k views

I was told that if the Moon had a retrograde orbit, tides would have a faster rhythm. Why is that?

Would this be because tidal deceleration causing the Earth to spin faster or are there other actions in play that I haven't considered? Would the Earth even spin faster because of the tidal ...
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4answers
3k views

Why has Earth's core not become solid?

The Earth is billions of years old, yet its core has not yet cooled down and become solid. Will this happen in the foreseeable future?
3
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1answer
62 views

Electromagnetic radiation bending on Earth

Most articles say that a radiowave is able to propagate itself beyond the horizon because it is reflected off by the ionosphere (and the Earth itself). But do radio waves also get bent according to ...
0
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0answers
17 views

Direction of CMB and magnetic fields?

Measurements show the CMB is warmer to the North. Could more photons coming from that direction of the sky, cause metals in the Earth to move in that particular direction? As the Earth orbits the ...
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votes
1answer
123 views

From where we can view earth moving?

Earth moves with a speed around $100000 \,\,km/h$, which will be amazing, but from where we can see that moving speed? If we far away from earth (outside of earth gravity) then can view its moving? is ...
10
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2answers
227 views

Where did the energy released due to gravitational binding energy of the Earth go?

The gravitational binding energy of the Earth is $2×10^{32} J $, so the same amount of energy must have been released during the Earth's history. According to this and this, the current internal ...
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0answers
25 views

Relativity question [duplicate]

If a rocket is traveling away from earth, why does time pass slower for the rocket if from the rocket's perspective, earth is going away from it?