Questions tagged [earth]
Questions regarding the planet on which humans live; the third planet from the Sun.
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How loud would the Sun be?
Sound can't travel through outer space. But if it could, how loud would the Sun be? Would the sound be dangerous to life on Earth, or would we barely hear it from this distance?
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How does the Earth move in the sky as seen from the Moon?
I just want to be sure I am visualizing this correctly, because it seems odd. The Moon is tidally locked to the Earth but there are wobbles to its motion due to libration. So from a point on the ...
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If Earth is tilted, why is Polaris always above the same spot?
Why is Polaris, the North Star, always above (or near) the North Pole? If Earth is tilted, Polaris' path should be in winter 23 degrees away from its path in summer, or not?
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How old is the oldest light visible from Earth?
Because light can only travel so fast, all of the light we see in the sky was emitted at a previous moment in time. So if for example we see a supernova or some other great stellar event, by the time ...
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Why does the Moon appear gray when passing between the Sun and the Earth?
Shouldn't the Moon appear as bright as a full Moon seen at midnight from Earth?
The photo was taken by DSCOVR at Lagrange point 1.
In the picture, The Moon appears dark gray. Of course the Earth ...
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Could any known, living organisms on Earth survive on Mars?
No life has been discovered outside of Earth (yet?), but do we know if anything that would be considered "living" on Earth could conquer Mars? (or maybe Venus?)
With the Mars One project on the way, ...
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Which is brighter, Mars as seen from Earth, or Earth as seen from Mars?
At their closest flyby, Earth is ‘new’ and dim from Mars, and Mars is ‘full’ from Earth and brightest as seen from Earth.
When Earth is 39 degrees from the Sun then Earth is brightest as seen from ...
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Why is the solstice the first day of summer, and not the central day?
Summer in the Northern Hemisphere starts on the day of the summer solstice. This is the day that the Northern Hemisphere receives more light from the Sun, due to the Earth's tilt. To my knowledge, the ...
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Why is the summer solstice night shorter than the winter solstice day?
I was looking at the sunrise and sunset times where I live (Aberdeen, Scotland) and I noticed something odd: the time between sunrise and sunset in winter is longer than the time between sunset and ...
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Why does the Earth have a tilt of ~23°?
Is there a reason that the Earth has the tilt that it does (~23°)?
How do we know which way is supposed to be 0°?
Does this tilt have major consequences on the planet?
Has it changed and will it ...
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Are we made of the stuff of one star or more stars?
[T]his coincidence enabled stars in the late stages of their lives to turn helium into carbon, oxygen and most of the other atoms that you and I are made of. [...] [W]e're made of star stuff.
Max ...
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Simple experimental evidence that Earth revolves around Sun
What are the simplest experiments or calculations that give evidence that the earth revolves around the sun? Can you please explain them and reference the history? Many simple explanations such as ...
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Is it a coincidence that both the Sun and the Moon look of same size from the Earth?
The Sun is huge, when compared to the Moon. Despite the huge difference in their size and distance from Earth, is it purely coincidental that they both look almost the same from Earth?
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Can you see man-made lights on the dark side of the Earth from the surface of the moon with the naked eye?
This question is prompted from a comment on this answer:
Could a person on the surface of the moon see man-made lights on the dark side of the Earth with the naked eye? If not, how much magnification ...
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Does the Earth have another moon?
I was just wondering what are the chances that there is a small object (say less than 1 km but more than few meters) that orbits the Earth but has remained undetected by us? Are we actually ...
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Where in space would the Earth and Moon appear to be the same size?
If I'm directly in between the Earth and Moon, what distance from the Earth would I have to be so that the Earth and Moon have the same apparent size?
How big would the moon appear compared to it's ...
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Why would it be very light out at 3 AM?
My brother noticed something very odd last night: it was amazingly light out when he stepped outside for a smoke even though it was between 3 AM and 3:30 AM EDST and we are near Toronto Ontario Canada,...
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Was the Geocentric Model correct at all?
It's easy to find resources stating that the heliocentric model is right and geocentric is wrong.
But how wrong was it? Was it correct in any way?
It was built on incorrect assumptions, but despite ...
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Can an object from a natural process escape earth gravitation?
I'm no expert, but I once studied basic from advanced physics and understand
gravity
action/reaction
escape velocity of 11.2 km/s from the earth surface
escape velocity changing as the object go far ...
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If suddenly "knocked" or perturbed from its orbit, would gravity eventually return the Earth to its original orbit?
If suddenly "knocked" or perturbed from its orbit, would gravity eventually return the Earth to its original orbit?
I am curious as to whether this is even possible.
It seems to me that ...
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Why is the Moon receding from the Earth due to tides? Is this typical for other moons?
After reading the Q&A Is the moon moving further away from Earth and closer to the Sun? Why? about the tides transferring energy to the Moon and pushing it from Earth, I have a question:
How is ...
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What is the distance that the Moon travels during one orbit around the Earth?
Also, does it always take the same amount of time, or does it fractionally differ on each revolution?
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How stable are Lissajous orbits?
Now that the Gaia Space Telescope is on it's way to the Sun-Earth L2 Lagrangian point (SEL2), I start wondering about the stability of Gaia's orbit there. The Planck Telescope is already there, as was ...
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How many planets have we discovered that can support human life?
I have heard a lot of buzz about distant planets that could potentially be second homes for human existence, but what is that approximate number?
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Why doesn't Earth's axis change during the year?
My understanding is that the Earth's axis points in the same direction in space during its entire orbit around the sun. And this is what causes our seasons.
My question is why doesn't the axis follow ...
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Is the Earth going to evolve towards Mars' fate or Venus' fate?
Upon reading on this site (and many others), one can think that Mars might have supported life in a distant past (discovery of liquid water, valleys, mountains...).
On the other hand, Venus is the ...
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Do other planets in our solar system experience eclipses or is this unique to Earth?
Here on Earth we get to experience lunar and solar eclipses. Is this pure coincidence that everything happens to line up?
Do other planets in the solar system experience this phenomenon or is this ...
user96
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Did the earth form outside the solar system?
Why isn't it possible that the earth formed outside the solar system and got attracted later by the Sun?
I just need arguments to defeat this hypothesis.
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Will Earth lose the Moon before the Sun goes into supernova?
I've read that the Moon is moving away from the Earth by 1-3cm per year.
Is this enough to make the Earth lose the Moon before the Sun goes supernova?
I'm asking because I would like to do the ...
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Why haven't Earth and Venus got any tiny moons? Or have they?
Why haven't some meteoroids gotten caught in Earth's or Venus' orbit?
AFAIK most meteors are tiny fragments from comets. Shouldn't some comet tail sometime have passed Earth orbit at velocities ...
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Why do stars appear to twinkle?
Sometimes at night you will look up to the stars and they will appear to twinkle, getting brighter and darker in bursts.
Why does this happen? Is this because of our atmosphere? Would they twinkle ...
user96
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Official degrees of earth’s rotation per day
What is the official degree to one decimal point please, of the earth’s rotation in one single day. Can it be confirmed that it is exactly 360.0 degrees using official data? Thank you in advance.
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Moon's orbit around the Sun
The Earth revolves around the Sun and the Moon revolves around the Earth.
Out of curiosity I started thinking about the orbit of the Moon around the Sun and expected (assumed) it to be as follows:
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If the moon wasn't receding from Earth, what would be the impact on the weather and tides?
Moon is slowly receding from Earth, which means that after its formation it was much closer to the Earth than now. How would weather look like if it wasn't receding at it would be now as close as at ...
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Why don't we have 2 Summers and 2 Winters?
Due to Earth's elliptical orbit, its distance from Sun varies by almost 5 million Kilometers (147 million Kilometers at closest point & 152 million Kilometers at farthest point, i.e. almost 3% of ...
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Will the Earth ever be tidally locked to the Moon?
From my basic understating,
Momentum is being transfered from the Earth's rotation to the Moon's orbit by tidal friction. The Earth's rotation slows down and the Moon receedes from the Earth as it ...
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What will a lunar eclipse look like from moon?
What will a lunar eclipse look like from moon? Will earth become a completely dark circle?
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How bright is the full Earth during the lunar midnight?
At lunar midnight (i.e. the new moon as seen from Earth), the Earth is in its full phase with its entire disk in sunlight, and it is the brightest object in the lunar sky. How bright is it, and how ...
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How one can establish that the Earth is round?
I am asking this question out of curiosity.
Currently, I am reading the book: A Brief History of Time. In Chapter 1, the author discusses about Aristotle's conclusions about spherical Earth.
For ...
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Does Sun have a reflection on Earth?
The new Google Maps1 presents an actual view of Earth, with the current position of Sun illuminating half part of Earth in real time. It is quite an exquisite view.
My question is based on the ...
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What if Earth and Moon revolved around each other like Pluto and Charon?
What would be different for us if Earth and Moon revolved around each other like Pluto and Charon do?
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Why are there no stars visible in cislunar space?
It’s very puzzling that the moon landing had no stars in the background, the ISS clips have no stars in the background. I listened to multiple astronaut interviews speak on what it looks like up in ...
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Can a satellite stay in one place but not above equator? [closed]
I know that there are geostationary satellites that are always seen in one place in the sky and that they all are located in the equatorial area. I wonder if it's possible for a satellite to "...
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How did the Earth come to be in orbit around the sun?
I'm not sure if this post should be in the physics subject forum, but this seems to fit here too. I have been reading a book about chemistry and how the universe came to be with the theory of stars ...
bobthebuilder
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Why does each and every planet of our solar system have an unique axial tilt angle?
Why do planets have an axial tilt? From the above image we can see that each planet's axial tilt angle varies and differs from the others.
What was the cause of this, was this from the beginning of ...
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If Earth didn't rotate, would we feel heavier? [closed]
Suppose the Earth's rotation slowed for some reason. Would the lack of centrifugal force cause us to feel heavier than normal?
Likewise, if Earth's rotation increased, would we feel lighter as ...
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If we found evidence of life on Mars, how would we know that it originated on Mars rather than Earth?
Consider this scenario. One of the probes sent to Mars either very soon, or within the next century, finds conclusive micro-fossil evidence that life once existed on Mars.
One theory today that is ...
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Were effects of a planetary magnetic field reversal observed on other planets than Earth?
From geological records in rocks and minerals we know that the magnetic field of Earth changed its polarity multiple times in the history. See Geomagnetic reversal.
Was a similar process of a ...
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Is it at all possible for the sun to revolve around as many barycenters as we have planets in our solar system?
Though it is understandable that the sun and the earth may be revolving around a barycenter, but, if so, not only the sun and Jupiter should also be revolving around some barycenter, the same should ...
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Why is the L3 Lagrangian point not perfectly stable? And why is the Earth-Sun L3 point a bit less than one A.U.?
I suppose the answer might involve general relativity, but still....
The L4 and L5 points are considered, theoretically, long-term stable, but not L3, on the exact opposite side of the Sun... And it ...
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