Questions tagged [earth]

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

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What else can we learn from a Foucault pendulum? Have they ever been used to determine anything more than that the Earth rotates on its axis?

Background Each semester we have to make up projects for each course. This semester I took Cosmology and Astrophysics and we covered a vast amount of topics, from luminosity of stars to Einstein's ...
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-3 votes
2 answers
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Which is closer to the Earth, Phobos, Deimos or Mars? [closed]

Which one is closer to the Earth, Phobos, Deimos or Mars? None of the answers that I find actually answer my question.
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1 answer
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Does Earth's rotation cause any structural changes in the Earth? [closed]

I tried searching for this and while all results talks about changes of day and night, impact on direction of wind, cyclones, etc, they do not say whether it causes any structural changes in the long ...
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Why isn't Spring equinox on 1st of April?

AFAIK the summer and and winter solstices are based on longest day and longest night doesn't fall on 1st of Jan and July 1st because we consider the day to begin and end when the middle of the sun is ...
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1 answer
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How far can the best telescope see in outer space from Earth?

I was wondering what is the farthest the best optical telescope can see into outer space from Earth. What causes them to see so far?
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7 votes
1 answer
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Earth-Moon Barycenter Perihelion

I am trying to implement an algorithm I created to get the sun rise, transit and set accurately, but in order to do that I need to get the Earth-Moon barycenter (EMB) perihelion, and not the Earth ...
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6 votes
1 answer
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Doubt about a computation in Jules Verne

In his Aventures de trois Russes et de trois Anglais dans l'Afrique australe (The Adventures of Three Englishmen and Three Russians in South Africa), Jules Verne describes in some detail the geodetic ...
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2 votes
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Small Angle Approximation Discrepancy in Horizon Dip Angle

Let's get back to the classic astronomical problem of calculating horizontal dip angle using small angle approximations. Let, our observer is a point object situated at an height $h$ on the earth ...
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1 answer
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different corresponding coefficients in formulae for a mean element

why do they take λ₁ = 1 295 977 422.834 29ʺ from subsection 5.8.3.¹ (mean elements referred to the mean dynamical ecliptic and equinox J2000), and not λ₁ = 1 296 027 711.034 29ʺ from subsection 5.9.3.¹...
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-1 votes
1 answer
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Can a destroyed earth reform into another habitable planet?

Let's say a planet-sized object collide with earth, disintegrate it, then reform at the same orbit as earth. Will it eventually formed into a habitable, life-supporting planet with living organism?
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How to calculate the Sun's declination for a specific location based on the axial tilt of Earth throughout the year?

How to calculate the Sun's declination for a specific location (i.e. relative to a specific coordinate) based on the axial tilt of Earth throughout the year? Any algorithm for code available in this ...
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2 votes
1 answer
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Earth-Mars-Moon or No Moon Barycenter Orbit Possible?

Could an object of sufficient mass deflect Mars so that it ends up stably orbiting an Earth-Mars-Moon barycenter? What would the distances eventually become between each orbiting body? What if the ...
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2 votes
1 answer
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How to calculate the Earth's axial tilt (obliquity)

How can I calculate the Earth's axial tilt in degrees. I tried Skyfield, Poliastro and PyEphem. I know it's changing -0.47"/year, and it was ...
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1 answer
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When does DSCOVR see the Moon transit Earth?

In 2015, NASA published the first images of the Moon transiting the Earth as seen from DSCOVR. The text accompanying these images says such a transit would be captured on camera about twice a year. I ...
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How strong is the evidence or argument for the Moon as stabilizer of Earth's axial tilt? [duplicate]

It's thought that the Moon stabilizes Earth's axial tilt, and so without it, seasons as we know them could not exist i.e. there could be extremes during periods where the tilt approaches 90 degrees. ...
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9 votes
3 answers
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Why is the composition of the sun so distinct from that of earth?

Given that the sun is – in astronomical distances – quite close to the earth, why are the two composed of such distinctly different substances? Sun Composition Hydrogen 74.9% Helium 23.8% Oxygen ~1% ...
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5 votes
1 answer
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Would a system consisting of Earth and Venus orbiting around a common center be stable in the long-term?

Earth and Venus and very close to each other in mass and would both orbit around a point in space positioned almost perfectly in between the two. Assume that this system is 1 AU from the Sun and the ...
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Was the young Sun cooler or hotter than it is today?

Generally, astrophysicists say that the young Sun was only about 70% as warm as today, which leads to the alleged 'Faint young Sun paradox' about how a young Earth could have been as warm as it (again,...
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20 votes
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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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3 votes
2 answers
231 views

Pendulum clock correction

I'm trying to solve this task: The pendulum clock was transported from the Earth's equator to Antarctica (in the vicinity of the southern geopole) for scientific experiments. Estimate the pendulum ...
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11 votes
3 answers
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Can you see the shadow of a spaceship on the Moon while looking towards the Earth?

It's a classic movie cliche. We see the surface of the Moon with the Earth in the distance and a dark shadow of an invading alien spaceship slowly covering the landscape. We see this in the opening ...
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2 votes
1 answer
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Is it more accurate to measure distances from Mars?

I'm trying to figure out answer to this task: At a certain level of development of the Martian civilization, scientists of this planet began to measure distances. Will their measurements be more or ...
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1 vote
1 answer
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Calculation of time delay in NASA's STEREO project

I'm trying to solve this task: Astronomers recently managed to get an image of the entire surface of the Sun for the first time. This became possible thanks to the STEREO project. In 2006, two ...
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3 votes
2 answers
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2 points on Earth’s surface, 1 second apart in time

I’m hoping to find a method (probably some modeling software?) that would allow me to find pairs of locations on the Earth’s surface that occupy the same point in space relative to the sun, one second ...
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5 votes
1 answer
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Calculate lines of equal solar altitude

I'm attempting to calculate lines of equal solar altitude, essentially a generalized case of the Earth terminator for solar altitude $ h $. For a given sun position with declination $ \delta $ and ...
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Is it completely false that the Sun does not revolve round the earth? In what sense? [duplicate]

This is a very naive question but I never fully understood this. For a system of two binary stars moving under the influence of their mutual gravitational forces revolve around their common center of ...
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2 votes
2 answers
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defining the period of an year on earth

While it is much simpler to define the duration (time) of ONE complete day (for earth), by simply calling it to be the period between sunrise to next sunrise (which we have currently divided into 24 ...
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2 votes
3 answers
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Neptune's eccentricity stability

Will Neptune's orbital eccentricity remain lower than earth's forever? It currently is at around 0.008, compared to Earth's 0.0167.
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3 votes
2 answers
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Which Venus scientists discovered the hole in the ozone layer?

After 21:00 in Venus: Earth’s Evil Twin or Just Misunderstood? (live public talk) from the JPL YouTube channel the person being interviewed "Sue Smrekar, Rocky ...
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2 votes
2 answers
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What are opinions of most planetary scientists on this study (link below), were there already some complex reviews in scientific journals?

I remember this two year old article from Universe Today about this study, "Stepwise Earth oxygenation is an inherent property of global biogeochemical cycling", by Lewis J. Alcott, Benjamin ...
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12 votes
2 answers
3k views

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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14 votes
4 answers
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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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4 votes
1 answer
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Why does the earth's axis move in the opposite direction to its rotation?

I know that precession appears when the axis of rotation of the planet is not perpendicular to the plane of the satellite's orbit and tidal forces applied to the equatorial belt tend to rotate the ...
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12 votes
1 answer
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If Theia really crashed into Earth, did it impact Earth's axial tilt?

The great-impact theory is widely accepted for the formation of moon. If Theia (often described as a Mars-sized rock) really crashed into Earth, did that make an impact on Earth's axial tilt?
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2 votes
1 answer
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What would happen if the Sun, Moon and Earth were isolated?

I am curious to know what would happen to Earth and life on Earth if all other heavenly bodies outside of our Sun, Moon and our planet Earth ceased to exist in some non-destructive way? (this includes ...
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20 votes
3 answers
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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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5 votes
2 answers
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How do scientists know that Earth used to spin much more rapidly?

News has just been released all over my news feeds about how paleontologists now believe that early photosynthetic organisms became much more efficient at producing oxygen after the Earth started to ...
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4 votes
2 answers
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How to resolve the Moon's observed angular velocity with that given by Kepler's Third Law

According to the sidereal period of the Moon's orbit around the Earth of 27.32166 earth days of 86400 seconds we get an angular velocity of $\frac{2\pi}{27.32166×86400} = 2.6617×10^{-6}$. (NASA's ...
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-3 votes
2 answers
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Is it possible for the Sun to lick the Earth with its flames?

The Sun ejects bursts of high-velocity matter, like fiery tongues reaching out. The Sun's magnetic field is able to deliver these bursts at different spots. Sometimes the flames are pulled back in by ...
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3 votes
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How does NASA estimate the size of the population of Near-Earth Objects (NEO) of diameter>140 meters?

In 2018, the US Congress passed a bill to allocate budgets and mission goals to NASA. Section 321 of that Bill mentions a goal for detection of NEOs of diameter >140 Km. Quote: (1) The George E. ...
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What is the size of the universe? [duplicate]

Will as a result of the continuation of technological progress in the twenty-first century more perfect telescopes or other astronomical instruments that will allow to know what is on the surface of ...
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3 votes
1 answer
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Is the 'spin' of Earth and the 'spin' of Mars a significant contribution to their angular momentum?

Is the 'spin' of Earth and the 'spin' of Mars taken into account as a contribution to the conservation of angular momentum? (and a contribution to the increasing/decreasing eccentricity?) Or - is the ...
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2 votes
1 answer
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How big is the Lorentz force on the Sun?

The LOFAR observations have made an estimate of the magnetic field of the Milky Way. The value in our region is very small. About 1/1000 of the Earth magnetic field. The Earth and the Sun move at a ...
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3 votes
2 answers
153 views

Winter in June in the future for North hemisphere

Kleppner and Kolenkow, An introduction to mechanics The period of the precession is 26000 years. 13000 years from now, the polar axis will not point toward Polaris, the current north star; it will ...
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3 votes
1 answer
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Mars is getting closer to Earth through its elliptical orbit becoming more eccentric. Do Earth and Mars keep getting closer? [closed]

A NASA Mars article says: Mars' orbit is more elliptical than Earth's, so the difference between perihelion and aphelion is greater. Over the past centuries, Mars' orbit has been getting more and ...
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4 votes
2 answers
278 views

How to actually obtain the parallax angles that are used to determine distances of stars?

I’m trying to understand how to measure the distance to nearby stars using the parallax method. My question is: how do you get the value of the p angle?
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0 votes
1 answer
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If the sun would be two times as big and with the same power output would temperature on Earth change? [duplicate]

Suppose the suns radius is increased by two. And suppose its emitted power doesn't change. Will we notice this on Earth? It will seem twice as big but apart from that what will we notice(if anything). ...
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What is the formula to input date, time and longitude. Where I can get latitude of the civil twilight back?

I am making a watch app, where I need to know where there is currently sun, and where it's not. I need to have some sort of formula/function to insert: date, time and longitude, and get back the ...
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1 vote
1 answer
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Why is the globe/compass symbol used more often than the globus cruciger for Earth? [closed]

Why is that symbol 🜨 used more often (or almost always) when portraying e.g. Earth mass or Earth radii than the globus cruciger ♁ ? From my point of view the globus cruciger fits much better as ...
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5 votes
1 answer
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What is meant by "revolution of Sun's apogee"?

While reading Translation of the Surya Siddhanta and of the Siddhanta Siromani(1861) - Bapu Deva Shastri, I stuck in the follwing. Chapter I, verse 41 & 42 In a KALPA (4.32 billion years), there ...
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