Questions tagged [earth]

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

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3
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2answers
204 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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3answers
3k views

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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1answer
113 views

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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1answer
31 views

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 ...
3
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2answers
140 views

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 ...
5
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1answer
141 views

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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0answers
62 views

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 ...
2
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2answers
74 views

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 ...
2
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3answers
91 views

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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2answers
78 views

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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2answers
175 views

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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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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4answers
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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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1answer
158 views

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 ...
12
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1answer
2k views

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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1answer
157 views

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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3answers
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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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2answers
143 views

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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2answers
383 views

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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2answers
87 views

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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0answers
86 views

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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31 views

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 ...
3
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1answer
227 views

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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1answer
86 views

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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2answers
140 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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1answer
124 views

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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2answers
223 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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1answer
92 views

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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30 views

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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1answer
111 views

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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1answer
200 views

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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44 views

Why does Earth have only one moon? [duplicate]

The moon was first formed billions of years ago when a Mars-sized object crashed into Earth. The pieces formed over time to create our moon. Why was only one moon formed? Could Earth have had other ...
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108 views

Would a future Dyson sphere or swarm around our Sun actually be beneficial to people on Earth? [closed]

A Dyson sphere or swarm's function is to harvests most of a star's energy, correct? However, a future Dyson sphere around our Sun would also block the Sun's rays from reaching Earth. Wouldn't it ...
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0answers
69 views

Calculating Angle Between Two Planets In Heliocentric Orbit

My goal is to calculate the retrograde of Mercury. What I've been working from is the book, Practical Astronomy With Your Calculator 3rd edition. I've made some progress, but I seem to be stuck with ...
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1answer
163 views

Maximum and minimum masses and sizes of giant planets?

What are the minimum & maximum masses and diameters of giant planets? Minimum end of the scale Earth has mass of 1 Earth mass and a mean radius of 6,371.0 kilometers, and thus a mean diameter of ...
4
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1answer
184 views

Questions on apparent motion of superior planets

Question Why is it that superior planets seem to oscillate up and down of the ecliptic, from the view of an observer on Earth, with a period equal to the planet's orbital period? Additionally, why do ...
6
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2answers
195 views

Why does Earth have a dip in the CO2 absortion spectrum from 14 to 16 micron?

This paper shows that there is a dip in the CO2 absorption spectrum of Earth. In essence the trough of the absorption of CO2 for Earth is cut into two separate troughs instead of 1 large trough. Why ...
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0answers
36 views

What is the period of the 'cycle' of Earth's ecliptic variation, relative to the 'invariable plane'? 70,000 or 100,000 years?

The plane of Earth's path around the Sun, the ecliptic, is different from the average of the solar system's as a whole (the invariable plane) by about 1.57°.... Our path around the Sun, though, goes ...
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1answer
74 views

Did we adapt to Earth or Earth to us? [closed]

I often hear that Earth is a unique planet because it has life. We also see a proper balance between plants and humans and other animals. Why is life not possible on another planet? Often people say ...
3
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1answer
70 views

How big and how far away would the moon be if earth was the size of Jupiter?

If the earth were the size of Jupiter, what would its 'moon' be in both relative size and distance? I did some quick figuring and think I roughly figured out that if placed at the position of the sun, ...
2
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2answers
64 views

Will the night sky ever be more stars than darkness? [duplicate]

Given enough time, will enough light from distant stars reach Earth so that our night sky will be more than 50% stars?
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4answers
7k views

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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0answers
121 views

Other side of Earth when the Dinosaur-killer struck

When the (Chicxulub) asteroid hit Yucatan, what was it like in the minutes, days and weeks afterward on distant locations on Earth? Related How loud was the asteroid that killed the dinosaurs?
3
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1answer
136 views

Synodic Day and Sidereal Day

If given the sidereal day, is it possible to derive the synodic day of Earth? If a derivation is possible, could anyone illustrate it or point me in the right direction? Wikipedia's Synodic day begins:...
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2answers
131 views

Do the earth and the moon reflect the different fractions of total solar radiation proportionally?

Reading on this website that: "All of the energy from the Sun that reaches the Earth arrives as solar radiation". "Solar radiation includes visible light, ultraviolet light, infrared, ...
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0answers
124 views

How is bond albedo calculated?

According to this website, Bond albedos are computed by calculating the ratio of the flux reflected by a planet (integrated over wavelength) to the total stellar flux incident on the planet. Three ...
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0answers
93 views

What is the highest albedo of the earth's surface facing the sun ever measured?

This website (page 26) claims that full-earth-shine on the moon is 100 times greater than full-moon-shine on earth. The figure 100 is made up of the difference between the size of the earth and the ...
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1answer
98 views

How can the author of this article conclude that earth-shine on the moon is 100 times brighter than moon-shine on earth? [duplicate]

I don't understand the reasoning of the author of this article, on page 26. How can he conclude that full earth-shine on the moon is 100 times brighter than full moon-shine on earth?
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2answers
54 views

Which unit is most suitable in comparing needed light intensity for night reading on the Moon, vs on Earth?

Which unit is best to use, and why, when determining how many times easier it is to read a newspaper (or any other printed text) on the moons surface at night under a full earth, compared with reading ...
2
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1answer
196 views

Scholarly work on the gravitational disruption of a rocky planet by a close pass with another planet?

note: While the apparently abandoned question Effects of a rogue planet passing between the Earth and the Moon? (inspired by Thundarr the Barbarian) asks for speculation and was answered with it, this ...

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