The earth tag has no wiki summary.
45
votes
8answers
5k views
Proof that the Earth rotates?
What is the proof, without leaving the Earth, and involving only basic physics, that the earth rotates around its axis?
By basic physics I mean the physics that the early physicists must've used to ...
41
votes
2answers
6k views
Was the 2013 meteor over Russia stronger than an atomic bomb?
Reports of the Russian meteor event (2013) say that it released more energy than 20 atomic bombs of the size dropped on Hiroshima, Japan:
Scientists estimated the meteor unleashed a force 20 times ...
28
votes
8answers
6k views
Would it matter if the Earth rotated clockwise?
In the Futurama episode "That Darn Katz!" they save the world by rotating the Earth backwards saying it shouldn't matter (which direction Earth rotates). If Earth rotated clockwise and remained in ...
22
votes
4answers
2k 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 ...
18
votes
4answers
2k views
Would you be weightless at the center of the Earth?
If you could travel to the center of the Earth (or any planet), would you be weightless there?
16
votes
8answers
13k views
Why doesn't the Moon fall upon Earth?
Why doesn't the Moon, or for that matter anything rotating another larger body, ever fall into the larger body?
15
votes
3answers
482 views
Does the Moon's core still contain significant heat?
On earth, using earth-sheltering techniques can significantly reduce the temperature fluctuations on a structure. Would the same statement be true as well on the Moon? Does the Moon's core still ...
13
votes
2answers
255 views
Is the length of the day increasing?
In Frontiers of Astronomy, Fred Hoyle advanced an idea from E.E.R.Holmberg that although the Earth's day was originally much shorter than it is now, and has lengthened owing to tidal friction, that ...
12
votes
1answer
163 views
Impact location that created the moon
I was reading an article today about the 1000th orbit of the Lunar Reconnaissance Orbiter, and as many of you know NASA created an animation that simulates the history of the moon. It is speculated ...
11
votes
4answers
1k views
Does Earth have a code name?
Everything we discover in the sky get eventually a code name, like NGC 7293, Simeis 147, etc.
Does Earth/Moon have a code name too? Or it is just Earth/Moon, etc.?
11
votes
1answer
147 views
Relationship between Mars and Earth rotation
Is it by pure random chance that Mars and the Earth have nearly the same day duration (Mars day is barely 40 minutes longer, which is just 3% difference), or there is some causal relationship between ...
11
votes
1answer
111 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 ...
10
votes
1answer
39 views
Why did the june 2011 lunar eclipse last so long?
It was kind of hard to miss the lunar eclipse this week, although I didn't see it in person (Sod's law means that on every relatively major astronomical event clouds cover where I am). From what I ...
10
votes
1answer
561 views
What will happen if a gamma-ray burst hits the Earth?
Is there any probability that a gamma-ray burst (GRB) could affect the Earth?
9
votes
1answer
299 views
If the Earth didn't rotate, how would a Foucault pendulum work?
How does the Foucault pendulum work exactly, and would it work at all, if the Earth didn't rotate?
8
votes
1answer
157 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 ...
8
votes
5answers
208 views
sun-moon-earth anomaly
When one looks at the sun and the moon in the sky together, why is it that the illuminated crescent of the moon does NOT "point" at the sun?
(More correctly the perpendicular bisector of the straight ...
7
votes
2answers
221 views
Huge buildings affect Earth's rotation?
Does constructing huge buildings affect the rotation of the Earth, similar to skater whose angular rotation increases when her arms are closed comparatively than open?
7
votes
2answers
249 views
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 ...
7
votes
4answers
3k views
How long would a lever have to be to move the planet Earth?
Give me a lever long enough and a
fulcrum on which to place it, and I
shall move the world.
-Archimedes
How long would that lever have to be?
That is to say, how long a lever ...
7
votes
3answers
66 views
Are there any Earth-Meteorites on Earth?
A follow-on from this question, if meteorites can come from Mars, it seems they could have come from Earth and ended up back here (though I'm guessing that to be less likely). Do we have any evidence ...
7
votes
1answer
236 views
How much does the curvature of space change the volume of Earth by?
If we assume space is flat the volume of Earth is:
$$ V = \frac{4 \pi R^3}{3} = \frac{4 \pi (6378.1 km)^3}{3} = 1.086 \times 10^{21} m^3 $$
The Einstein field equations, however, predict that the ...
6
votes
3answers
348 views
How is it that the Earth's atmosphere is not “blown away”?
The Earth moves at a high rate of speed around the Sun, and the solar system is moving quickly around the Milky Way. How is it that the Earth's atmosphere is not “blown away”?
6
votes
4answers
253 views
Why is the water on the surface of the Earth?
What makes the water stay on the surface? Why the earth does not absorb the water in it?
6
votes
2answers
156 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 ...
6
votes
1answer
78 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 ...
5
votes
4answers
377 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 ...
5
votes
4answers
681 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?
5
votes
1answer
299 views
Why does the sun “shine brighter” some days?
Today, the sun seems extremely bright; more dazzling than usual, and even the roads seem to be brighter so it's not just when you look up in the sky. Is more light actually getting through (perhaps ...
5
votes
2answers
251 views
Do we have any effect on the rotation of he earth?
We walk or ride on our vehicles to our destinations daily. Does our movement have any effect on the rotation of the earth according to Newton's law? What will be the effect if we move all the peoples ...
5
votes
2answers
763 views
If there was a black hole on earth, what would it look like?
If an answer does exist, I'd love to hear it. I'm trying to incorporate a doomed earth story in something I'm writing, and the end of the world I'm going for is a black hole.
Let's say the black hole ...
4
votes
2answers
362 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 ...
4
votes
3answers
693 views
How do we know that earth is not perfect sphere?
I've just read here that:
Equatorial radius = 6378.16 kilometers. Polar radius = 6356.78
kilometers, so the difference in circumference is 71.1 kilometers. It
is not a perfect sphere, but kind ...
4
votes
2answers
143 views
Cancel out Earth's Magnetic field
Is there any tools except helmholtz coil to cancel out earth's magnetic field to calibrate magnetometers in practice.
4
votes
1answer
202 views
If the Moon had gravity as good as the Earth and a magnetic field could it have supported life?
If the Moon had gravity as good as Earth and a magnetic field could it have supported life? Because if the Moon had gravity, it could have retained water more than is present today on the surface.
...
4
votes
2answers
309 views
How long was a day at the creation of earth?
Since the earth is slowing its rotation, and as far as I know, each day is 1 second longer every about 1.5 years, how long was an earth day near the formation of earth (4.5 billion years ago)?
I ...
4
votes
2answers
64 views
Attenuation mass-thickness for sunset light
We are able to look directly at the sun near sunset and sunrise, which clearly demonstrates the fact that our atmosphere attenuates visible light. Let's imagine it follows the typical attenuation ...
4
votes
1answer
89 views
How much negative charge do I accumulate by touching the earth?
The Earth carries a negative electric charge of roughly 500 thousand Coulombs (according to different sources I've seen). If I touch the Earth I should therefore pick up some of this electric charge ...
4
votes
1answer
68 views
How would gravity change on a planet rotating around itself very fast?
Let's take a planet identical to Earth, but with rotation speed multiplied by ten thousand. What would happen with the gravity if it was spinning madly around itself? Would the centrifugal force make ...
3
votes
6answers
2k views
How fast is Earth moving through the universe?
As the galaxy is moving and the solar system orbiting the galaxy and the Earth orbiting the sun. So how fast is each object moving and what is the fastest we move at?
Do we even know how fast the ...
3
votes
2answers
233 views
Deviation from Earth's orbit
How much orbital deviation is required for the Earth to get knocked out from current orbit so it either moves away from Sun or towards the Sun?
3
votes
1answer
287 views
How much energy would it take to blow up the earth?
There is a common statement running around that we as a species has enough nuclear weapons to blow up the earth several times over. What I want to know is: by how many orders of magnitude is that a ...
3
votes
1answer
89 views
Under what practical conditions would Earth's atmosphere be a dilatant?
I have read and heard in many places that when the astronauts of Apollo were coming back to Earth, they had to determine the best angle of attack to re-enter the atmosphere. This is usually indicated ...
3
votes
4answers
214 views
Why a day is divided by 12/24 hours? Why the number 12?
Why a day is divided by 12/24 hours? Why the number 12? Why not using 10 or 6 or 14, 16? Who invented this? Any physical reasons behind this?
3
votes
4answers
388 views
Angular momentum power plant on Earth
If tidal power plants are slowing down Earth's rotation then is it theoretically possible to build a power plant that would drain energy from Earth's angular momentum (thus slowing down it's ...
3
votes
1answer
554 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?
3
votes
1answer
171 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?
3
votes
2answers
169 views
What would the effect be of a small black hole colliding with the earth?
If a small black hole (say about .1 mm radius or 1% of Earth's mass) came flying along at the speed of a comet or higher and impacted the earth, what would happen? Would it pass through the earth (and ...
3
votes
3answers
112 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 ...
3
votes
1answer
118 views
Can Earth's Magnetic Field Create Electricity?
If the earth has a magnetic field, can it, in theory, be run through a conductive metal coil to create electricity?
