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Questions tagged [earth]

Questions regarding the planet on which humans live; the third planet from the Sun.

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Why would there be no day/night cycle even though the firmament would still be rotating, according to Copernicus

In chapter 6 of "The Revolutions of the Heavenly Spheres" where Copernicus maintains that the heavens are immense compared to the size of the Earth, the Edward Rosen translation of the book states ...
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1answer
106 views

How did we first determine the Earth's departure from sphericity?

I'm quite interested to know the history of the study of the Earth's departure from spherical symmetry. What were the first methods used to model the non-spherical geometry of the Earth? For example, ...
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Earth shape and rotation

Imagine a helicopter that took off from point A and goes vertically in the air to a certain fixed point B in the atmospheric area at a certain fixed altitude with enough fuel to stay there (at point ...
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1answer
311 views

How long was an early Earth year? [duplicate]

Roughly how long did it use to take for the early Earth 4.5~ billion years ago to complete one revolution around the Sun? (I know the Earth was spinning much faster, so a day would only take 2-3 ...
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257 views

If a comet strikes a glacier, does it make a print on the land below?

The Younger Dryas Impact Theory describes an asteroid impact in Northern America, possibly the eastern part of Hudson Bay, which contributed to the end of the last ice age. If a comet strikes a ...
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1answer
90 views

How have we measured the radius of the Earth (old and new)?

I'd imagine ancient methods are fun exercises in geometry. how has the measurement has evolved over time? The first method is credited to Eratosthenes. He knew that during the summer solstice in ...
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1answer
69 views

How are the elevations of the poles proportionate to distances of earth that have been traversed according to Copernicus

In chapter 2 of "The Revolutions of the Heavenly Spheres" where Copernicus maintains that the Earth is spherical, the Edward Rosen translation of the book states that the elevations of the poles ...
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2answers
294 views

Which would be safer: removing hydrogen or adding hydrogen to our sun?

If we want to extend the lifespan of our habitable zone safely, would it be safer to institute a yearly 'tax' on our suns outer layer of hydrogen, or a yearly 'subsidy' to our suns outer layer of ...
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1answer
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How can I calculate the time between sunset and actual darkness?

I would like to know the time it takes to go from sunset to dark based on GPS location. In addition, ideally I would also like to have a formula that determines the percentage of sunlight at each ...
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2answers
732 views

Size and Mass of a typical “small” asteroid that impacts the Earth?

I'm looking for some realistic data about the size (in meters) and mass (in kg) of a typical small asteroids that impact the Earth, without disintegrating in the atmosphere. Any suggestion ?
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549 views

Umbra, penumbra and antumbra

I'm trying to understand following schema of the wikipedia page here. Image subtitle is "Umbra, penumbra, and antumbra, for a lunar eclipse". Distances and sizes are not to scale. If distance ...
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3answers
161 views

Problem about orbiting of a satelite

Problem: There is an satellite that orbits the Earth. Its orbit is circular and its orbital plane is perpendicular to Earth's Equatorial Plane. It orbits is such that a person who is on equator see ...
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2answers
309 views

When will the Moon spiral away from Earth? [duplicate]

I am actually doing this for science extra credit. My teacher said that we would die if the moon got too far away. He wants us to figure out when this will happen.
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1answer
187 views

How far away does the Moon have to be until Earth doesn't feel its effects? [closed]

How far in miles does the Moon have to be for the Earth not to feel its effects?
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2answers
350 views

Calculating length of summer solstice day using tilt and latitude

I want to be able to predict how long the summer solstice lasts at any part of world given the maximum tilt angle $φ = 0.4101524 \; \mathrm{rad}$ and the latitude $θ \; \mathrm{rad}$. I specifically ...
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2answers
264 views

Which constellation would appear to revolve around Denab,Vega or Thuban when axis of the earth would point toward them?

We have been calling the star by looking at which we can make out the direction of the North Pole the North Star. This was the only method at the disposal of the sailors during the days when they did ...
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1answer
190 views

Stellarium simulation

I'm interested lately in Stellarium and the functionalities which it provides especially scripting. I want to make a simulation that shows the celestial sphere with some planets like Venus, Mars, and ...
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1answer
107 views

Hole through the earth [closed]

I have a problem: If I would dig a hole through the earth, and jump right in, disregarding the rotation of the earth, I should come back out on the other side. However, orbital mechanics say ...
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2answers
321 views

If there was air between the Sun and Earth, how warm would we get?

Based on this question: How loud would the Sun be? If instead of a vacuum we had air between the sun and earth (let's say of the same composition we have here on earth) how warm would our planet get?
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4answers
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About how many revolutions has the Earth made around the sun?

The Earth is about 4.543 billion years old. However, the length of a year can be changed by anything from an impact to a natural cycle of orbit changes to a slow drift toward or away from the sun to ...
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2answers
332 views

As the Sun dies, does the Earth's orbit change?

As the Sun nears the end of its life and expands, would the Earths orbit get bigger as it moves out or would it stay in the same orbital plane and not move out? Therefore in the far off future, we'd ...
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1answer
316 views

Can Earth have a ring?

Why doesn't the earth have a ring? If solid material such as dust and moonlets, and common components of satellite systems are brought nearer to the Earth, then what will happen? Will it take the ...
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1answer
580 views

If earth changed its orbit, what would happen to the moon?

Let there be an accelerating force acting on earth over an arbitrarily long time to change its orbit around the sun (e.g. by asteroids repeatedly passing by close to earth (intentional or not) or ...
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3answers
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Determining latitude and longitude in bad weather

In Sobel's famous book 'Longitude', she described the story of Harrison. I still have one question. What if it is cloudy on the sea? In this case, the sailors have nothing to compare with, right? This ...
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1answer
2k views

Could an object block out the Sun from Earth's view for 3 hours?

how large, massive, far away (from earth), and fast would an object (planet-like) have to be to block out the Sun for 3 hours and not disturb Venus, Earth, or the Moon?
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Why does the traslation movement of the earth last the same time as the four seasons?

Why does the traslation movement of the earth last the same time as the four seasons? The seasons could take 100 days or 200 or 20 years (aprox. like in GoT)... but exactly (exactly???) 1 year. Why? ...
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80 views

Age of a planetary body

We quote that the Earth is about 4 billion years old. However earth started with billions of cigarette smoke sized particles. What event or size or something do we use to say this is the start of ...
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2answers
758 views

What causes the Earth to have gravity?

I've always wondered how our planet Earth or any other large spheroid-shaped thing in our universe has gravity? Does it have a small black hole on its core causing it to have gravitational force? ...
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2answers
2k views

Transformation from Geocentric Coordinates into Equatorial Coordinates?

I have the moon's position in equatorial coordinates (RA and Dec) and now I want to calculate same moon's position in terms of earth centered coordinates i.e. Geocentric (latitude & longitude). My ...
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1answer
809 views

'Very High Noon' - Sun directly overhead

Twice a year the sun is at a certain angle south (or north) of the equator between The Tropic of Cancer and The Tropic of Capricorn. At that time the sun will be exactly overhead for people at the ...
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2answers
177 views

What would be the difference in distance between earth and moon on supermoon night (14 November 2016)

As we all know the usual distance between earth and moon is 384,400 km. But i was thinking how much closer it will be on 14 November 2016, as it will be a supermoon, the brightest and biggest moon in ...
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1answer
4k views

Is it same distance Equator & Prime Meridian? [closed]

i just want to ask in earth what the difference between Equator & Prime Meridian & also want to know is it same distance Equator & Prime Meridian?
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2answers
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Distance to Sun at Perihilion and Aphelion at max and min Eccentricity

Title says it all. I'm putting together a presentation on Milankovitch Cycles, and I would like to bring up the difference in distance to the sun (km) at aphelion and perihelion when the earths orbit ...
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1answer
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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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3answers
650 views

Sudden Effects of Sun Disappearing [duplicate]

It takes 8 minutes for the sun's light to reach earth. If the sun were to instantly disappear, what would happen? I imagine that Earth would fly away on a path tangential to its orbit. What would ...
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4answers
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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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175 views

Energy deposition in planet Earth due to gravitational waves

The gravitational wave detected by the LIGO observatory acted on planet Earth streching and shrinking it a little bit. I assume that not all of this action was fully elastic and that some energy of ...
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2answers
587 views

Can Earth host another natural satellite than the Moon?

Are there orbits with long-term stability (astronomical time scales) around Earth? Low altitude orbits will decay due to friction with Earth's atmosphere. Inside Earth's Roche limit, a Moon could not ...
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1answer
358 views

What makes the Earth infinitely rotating around its axis

I was reading two sites before I posted the question here. One site says something like that the collisions in Universe eventually set the planets rotating, another site says that our planet is formed ...
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1answer
86 views

Measurement precision of celestial events

The local weatherman declared that fall starts at exactly 10:21am (local time). Ignoring the fact that seasonal boundaries have multiple definitions (meteorological, astronomical, etc.), what he ...
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1answer
330 views

The Hollow Moon Story [closed]

I've heard on various programs (yes TV) with "supposed" experts in various fields that there is evidence which would suggest that the moon could be hollow. The experts ranged from scientists, sound/...
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1answer
373 views

Effects of the solar tide on planets

It’s well known that (lunar) tides on Earth result in a transfer of angular momentum from Earth proper to the Earth–Moon orbital motion. That’s why the Moon resides now in a high Earth orbit, and ...
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486 views

Angles of sunrise and sunset viewed from a surface anyway oriented

I need to understand how to calculate the angles of the sunrise and sunset viewed from a surface oriented against the azimuth and the horizon plane, and for any day of the year. For example, I have ...
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1answer
49 views

Observations of a perigee coincident with a full Moon

Hopefully this will be a quick and easy question, with a quick and easy answer, but why is it that we observe a perigee Moon coincident with a full Moon approximately every 13 months? Is this related ...
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2answers
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Decreasing rate of Earth's rotation: where does the power go?

I understand from Wikipedia that, "The length of the day, which has increased over the long term of Earth's history due to tidal effects, ...". If the angular velocity of the earth is decreasing then ...
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4answers
2k views

What point does Earth actually orbit?

If we consider the two largest masses in our solar system - the Sun and Jupiter, by themselves, they will orbit a common barycenter which is somewhere offset from the Sun's center in the direction of ...
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2answers
624 views

Why do our clocks not go out of sync with the day over a year?

Ok, so our clocks time 24 hours, our planet takes 24 hours to rotate completely and our planet revolves around the sun in 365 days. Imagine at the start of the year, the side of Earth facing Sol is '...
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1answer
195 views

Jupiter orbiting time in Earth's orbit?

Imagine if Jupiter orbited the Sun at the Earth's orbital distance of 1AU. Would a planet of this size orbiting the Sun take 1 Earth year (365 days) to complete an orbit, or would the size of ...
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4answers
3k views

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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Do differentials in the Earth's density cause the flyby anomaly?

The flyby anomaly is an occasional, unpredictable, and as yet unexplained discrepancy in acceleration of satellites when they pass close by the Earth. It causes an increase of up to 13 mm/s during ...