Questions tagged [earth]

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

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14
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4answers
1k views

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 "...
4
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1answer
87 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?
2
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1answer
143 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 ...
20
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3answers
5k views

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 ...
5
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2answers
135 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 ...
4
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2answers
352 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 ...
-3
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2answers
85 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 ...
3
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0answers
82 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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0answers
28 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
209 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 ...
2
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1answer
84 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 ...
3
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2answers
136 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 ...
3
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1answer
119 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 ...
4
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2answers
200 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?
0
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1answer
80 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). ...
0
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0answers
27 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 ...
1
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1answer
103 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 ...
5
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1answer
191 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 ...
1
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0answers
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 ...
1
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0answers
106 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
62 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
101 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
votes
1answer
183 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
146 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
32 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 ...
1
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1answer
71 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
58 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?
21
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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,...
3
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0answers
116 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
120 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:...
2
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2answers
129 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, ...
1
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0answers
89 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 ...
0
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0answers
87 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 ...
0
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1answer
97 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
47 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
votes
1answer
156 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 ...
2
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2answers
76 views

Formula to calculate the apparent magnitude of Earth from arbitrary distances

I would like to calculate the apparent magnitude of Earth from various distances, say from the Voyager probe at this moment or from various stars in the sky. I know there must be a formula that I can ...
3
votes
1answer
164 views

Exact ecliptic position of Earth and Moon from Mars as photographed by Curiosity Rover?

I've been studying the idea of travelling through space and navigation - in particular: Apollo sextant (used by astronauts to plot the position of their spacecraft relative to stars). And, in order to ...
4
votes
1answer
146 views

Is Earth's rotation Slowing down or Increasing

Recently read that Earth is rotating faster than earlier1. However so far it is understood that earth's rotation is slowing down and to conserve the angular momentum Moon is going away from the Earth. ...
13
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4answers
3k views

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 ...
0
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1answer
176 views

If it only takes 8 minutes for that light to reach the Earth, what took up most of the time? [closed]

If it only takes 8 minutes for that light to reach the Earth, what took up most of all that time to get to the Earth?
2
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3answers
834 views

Will Earth rotate backwards in the future?

Hello recently I heave heard the earth will eventually start rotating in the opposite direction (ie sunrise from the west) . I am not sure if this is true, but a lot of sites are claiming it to be ...
3
votes
2answers
795 views

Does the earth spiral around the sun's movement/motion path?

I have watched the following video (How Earth Moves by Vsauce) regarding how earth moves: Here are some screenshots: I have some questions: Does the earth spiral ...
3
votes
1answer
74 views

What would the Earth's peri- and aphelion have to be in order to have the same seasons due to its orbit?

Imagine the Earth had no axial tilt but had seasons due to a very elliptical orbit. How elliptical would the Earth's orbit have to be in order to have about the same seasons as it has now (just with ...
1
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0answers
57 views

Meteor size and frequency distribution for Earth vs. moon or other planets?

I struggle to find an answer to the at-first-sight simple question if or how the size distribution and frequency distribution of incoming rocks hitting the ground or the atmosphere vary from Earth, to ...
1
vote
2answers
194 views

North node, South node correct understanding

What is the correct concept of the North node and South node? There is some conflicting information on the internet. Which one of these two is correct? 1. Sourced from some Astrology material - How ...
2
votes
1answer
110 views

Where did the nickel in the Earth's core come from?

Why is there nickel in the core of the earth? Does it come from collisions of two neutron stars? And how did we know the core of our planet is made of nickel-iron alloy? Thank you.
2
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0answers
22 views

The electron–cyclotron maser emissions from Earth

The first-ever detection of radio signals caused by the electron–cyclotron maser mechanism outside of the Solar System, on Tau Bootis b was recently published (here). This phenomenon causes huge radio ...

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