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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Exploding Earth

I have always heard that the Earth, due to its structure, cannot explode. Now, I'm quite fascinated by astronomy physics but I admit I only hold some more than basic knowledge. In any case, even ...
3
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3answers
301 views

Ozone Hole in the South Pole

Perhaps this should be a chemistry question, but it seems to have physics attributes. There's a perennial ozone "hole" around the south pole created by destruction from Cl based chemicals like CFCs. ...
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1answer
200 views

Earth is rotating [duplicate]

Possible Duplicate: Why does the atmosphere rotate along with the earth? If i take off from land on a helicopter straight above the earth surface to a certain height and stay there for few ...
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1answer
165 views

(Earth's) magnetic field

Always when we want to represent the magnetic field of the earth we see a similar image: My question is, what exactly does this show? What are the blue and orange lines, what do they represent? Why ...
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1answer
429 views

Deducing latitude from Foucault Pendulum

Suppose I set up a Foucault pendulum and observe that it precesses at a rate of 216.528 degrees per day. While I am observing this, a total solar eclipse occurs. Where am I, and what is the date? My ...
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2answers
259 views

Is it possible to use a balloon to float so high in the atmosphere that you can be gravitationally pulled towards a satellite?

A recent joke on the comedy panel show 8 out of 10 cats prompted this question. I'm pretty sure the answer's no, but hopefully someone can surprise me. If you put a person in a balloon, such that ...
0
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1answer
235 views

What is the gravity at the center of the Earth? [duplicate]

Possible Duplicate: Would you be weightless at the center of the Earth? Supposing there is a cavity at the center of the Earth, what is the gravity there? What will be its direction and ...
3
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2answers
222 views

The earth's magnetic field

This might sound like a silly question. Is it possible for the earth's magnetic field to actually destroy or harm earth? (implosion, crushing etc.)
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2answers
142 views

Moon and the moving train

While travelling by train (travelling West to East), it seems the moon is moving in opposite direction when seen from the window, but then it reverses its direction, after a certain amount of time and ...
3
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1answer
288 views

Earthquake as a transverse wave

I have a very simple mental picture that earthquake waves travel like shear (transverse) waves through the earth. a. Does the speed of this wave give any valuable information about the mechanical ...
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2answers
2k views

What does the phrase “limb of the earth” or “atmospheric limb” mean?

What does the term limb of the earth (see this question, for example) or atmospheric limb mean? The phrase strikes me as very odd, since earth is nearly spherical. Do other planets with atmospheres ...
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0answers
118 views

How far is the horizon, if a 2m tall man watches to the sea?

How far is the horizon, if a $r=2 m$ tall man watches to the sea? I have calculated that it would be even just about 6 km. if R = radius of earth( $6370 \cdot10^3$ m ). By pythagorean theorem we ...
3
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1answer
2k views

Do other planets have an effect in Earth's rotation and revolution?

Do Earth's rotation/revolution is regulated by other planets (and vice versa) in any way? How?
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1answer
206 views

Impact of Apophis

I read about the near-earth asteroid 99942 Apophis. It is in the first place of Potentially Hazardous Asteroids (visiting earth at an altitude of about 36,000km on 2028). But, scientists have ...
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1answer
270 views

Does a coronal mass ejection change solar neutrino emission rates?

Does the CME and neutrinos have any relation? CME is measured by Corona graphs.. How do they measure neutrinos coming from the sun? Does any of these have effects on earth's magnetic field or ...
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2answers
3k views

How much of sky can be seen on a typical night from a mid-latitude location?

I'm at about 40deg north so, assuming a clear southern horizon, I can't see things below about -30 or so (I actually don't know how far south). I also have a large portion that is circumpolar so it's ...
3
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1answer
179 views

Why isn't sunset time in sync with solstice?

The winter solstice in the Northern Hemisphere in 2011 is on December 22. But if I look at the sunset times for a location such as Washington, DC on the USNO site, the sunset time starts reversing ...
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1answer
268 views

What equations/constants were used to calculate the Kármán Line for Earth?

I am interested in how the original value of ~100 km was calculated for the Kármán line of earth. What equations and constants would need to be used to reproduce this value? Note: By constants, ...
2
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1answer
73 views

Sunrise time across the globe?

This question is more astronomy related, I started thinking when I heard from one of my friends living in Jiamusi, that Sun rise at 02:00 and sets at 14:00, I know that this place is more near to ...
0
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2answers
126 views

Is reversal of magnetic polarity in a planet an instantaneous occurence?

Just what the title states - Does reversal of magnetic poles in a planet refer to the point in time when reversal is complete? OR Does it refer to the entire drawn out process (assuming the ...
8
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1answer
407 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 ...
3
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3answers
237 views

On what planar regions are the Earth, Moon.. for that matter, all astronomical bodies, placed in the Universe?

When we are on Earth, we look UP in the Sky to see the Moon. How do we have to look at Earth from Moon.. Is it the way ? If so, how are these bodies actually placed in the space? Are all astronomical ...
6
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1answer
209 views

Axial Tilt and precession rate of exoplanets

The Earth's axis is 23.5 degrees away from othogonality to the ecliptic, and it takes about 26 000 years for it to precess fully. I have neither an intuitive sense nor the formula for precession ...
4
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1answer
1k views

Formula for getting time of sunrise at a particular location?

Is there a formula that can get sunrise at a particular latitude and longitude (and elevation from sea level)? If so, what it is? (Why does it work?)
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4answers
912 views

Why doesn't the Earth leave you as soon as you escape it?

I've always wondered, that since the Earth is moving at a very fast velocity around the Sun, why is it that when astronauts leave the Earth, the Earth doesn't immediately move away from them at ...