Questions tagged [earth]

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

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13 votes
1 answer
3k views

Earth is Tilted, but in reference to What Object / relative to what?

I am asking basic question on trying to understand on tilt. I know if I (as a human) tilt when standing on feet, my tilt will be in relation to gravity. For Earth, I am not able to understand, what is ...
3 votes
3 answers
3k views

If the Earth is rotating counter clockwise, how does the sun rise from east?

I was very confused when I watched this video from 2:18 till 2:45. And it seems very clear that if the Earth is really rotating from west to east, shouldn't be the Sun rising from west and setting in ...
4 votes
1 answer
219 views

What is the distance between sunrise and sunset along a parallel of latitude for declination other than 0?

I would like to calculate the distance between sunrise and sunset along a parallel of latitude, e.g., 45 degrees north. What I've done is: Earth's circumference at the equator is 40075 km. Earth's ...
7 votes
2 answers
1k views

How can Earth-Sun Lagrange points L1 & L2 even be semi stable considering the moon?

I know that the Earth-Sun Lagrange L1, L2, and L3 points are not considered stable over longer periods, especially when compared to L4 and L5... But, with the moon orbiting the Earth in the general ...
1 vote
0 answers
19 views

Geocentric position of lunar ascending node relative to the true equator and equinox of date, using skyfield

The following is what I'm doing currently. Am I missing something here? I'm unsure if I am converting in and out of Skyfield objects correctly, and there is any unaccounted for behavior i'm not seeing ...
6 votes
1 answer
119 views

Doesn't the moon actually make asteroid impacts on Earth more likely?

So the moon adds to the total mass of the Earth-Moon system so together there is more mass so then there should be more gravity due to the total system and the moon is small relative to how much ...
7 votes
1 answer
140 views

Where will all atoms on the Earth end up when the Sun engulfs the earth?

I am curious about what will happen to all atoms on the Earth including all of our atoms after the Sun engulfs the Earth? Will they become the part of the Sun's white dwarf? Or most of them will be ...
4 votes
1 answer
177 views

Voyager spacecraft distance from Earth

According with NASA JPL the earth catches up with the spacecraft because Earth is moving a lot faster than the spacecraft. Can one calculate the times when the spacecraft gets closest to Earth
7 votes
1 answer
145 views

Attempting to plot solar terminator using Python and Skyfield library

Problem I would like to plot the small circle defining the visible portion of Earth for an observer at position $P$ away from the Earth, on a 2D map. In the case of the Sun, this would be the solar ...
4 votes
3 answers
565 views

How do the phases of Venus prove heliocentrism?

I have been doing research about the Copernican Revolution, and one of the main arguments that caused many astronomers to change their minds was Galileo's observation of all phases of Venus. The proof ...
1 vote
2 answers
106 views

Calculate geographical location (latitude, longitude) from horizontal and equatorial coordinates, date and UT

Lets say I found myself in the middle of nowhere with small computer with some sort of offline astrometry engine (like locally installed astrometry.net). I have some sort of mount that precisely tells ...
15 votes
1 answer
7k views

Safest Place on Earth from Falling Meteorites

Where on Earth is statistically safer if an asteroid was to break up in the Roche limit and rain meteorites effectively resetting the Earth? I would imagine that a ring of falling meteors would form ...
18 votes
6 answers
12k views

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: ...
3 votes
2 answers
2k views

Why do the magnetic field lines of the earth go from south pole to north pole?

I saw these figures and could not get why the magnetic field lines are not pointing from the north pole towards the south pole but they do the opposite. Or also this picture which is about magnetic ...
1 vote
1 answer
106 views

How was the size of the earth determined 100/200/300 years ago?

How was the size of the earth determined 100/200/300 years ago? I know that by then the had better methods then the simple sticks and shadow experiment.
1 vote
1 answer
98 views

calculating apogee and perigee for moon and sun

The perigee does not necessarily happen when we have a full moon, using swevents we can easily determine the moon phases. Now can we use python to determine when ...
5 votes
1 answer
385 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. ...
10 votes
3 answers
5k views

Why are perihelion and the shortest day in the northern hemisphere different?

The orbit of Earth is elliptical and the nearest distance to sun is perihelion position. Should it not be the shortest day in the northern hemisphere?
1 vote
0 answers
67 views

Is there a specific area on the far side of the moon, directly below the L2 Lagrange point in the Earth/Moon system?

It seems like there should be, and if so I wonder how large an area it is, if it changes size over time, and if it moves or wobbles in some way. On the latst point, I imagine it would certainly wobble ...
-1 votes
1 answer
136 views

Earth and the Moon Question [closed]

(For the purpose of this question, I will refer to Earth's Moon as Luna to keep it separate from the general term of 'moon') I know the IAU has been hedgey about giving an official definition of what ...
14 votes
1 answer
4k views

What does the Earth look like when viewed from Saturn?

Are there any data from spacecraft that visited that planet? How large the Earth is when viewed from that planet?
1 vote
1 answer
176 views

Planets Named After Roman Gods, Except Earth

I’ve looked this up, but not necessarily sure the internet has the right answer. Why are the planets in our solar system named after Roman gods, except Earth, and why is only one of the nine planets ...
0 votes
1 answer
206 views

What is the distance between Stephenson 2-18 and Earth?

The distance between Earth and Stephenson 2-18 is 19,570 light years (1.15×10¹⁷ miles). The thing that makes this reasonable is because the Earth is in the Milky Way Galaxy and Stephenson 2-18 is in ...
4 votes
4 answers
848 views

Could the solar system survive in a void?

If the solar system were suddenly placed in the middle of a large void... would everything still function as normal? Would we even notice any difference here on Earth apart from the night sky? ......
0 votes
1 answer
210 views

Why don't scientists believe Earth's surface water came up from the mantle?

I read, periodically, that there is more water trapped in the mantle than there is in the oceans - possibly a lot more. If so, why don't any geologists believe that Earth's surface and near-surface ...
2 votes
2 answers
104 views

Mass accumulation rate and orbit-time of earth

According to me following reason of mass accumulation of earth has been completely overlooked so far. The sunrays that fall on the oceans travel deep into water and finally get converted into mass ...
2 votes
0 answers
43 views

Calendar times of equinoxes

I know that the dates and times of equinoxes are not the same every year, due to precession of the axis and perhaps other effects such as the year not containing an exact number of days. The ...
15 votes
4 answers
3k views

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 ...
3 votes
1 answer
148 views

Cooling the early earth

My son had this theory that the icy comets cooled the hot earth during the late heavy bombardment. What do we know about this cooling effect on the early evolution of the earth? He intended his theory ...
10 votes
3 answers
2k 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 ...
5 votes
2 answers
148 views

Why does earthshine fade out when night comes and reappear on the next evening?

While watching the Moon in the thin-crescent phase (a few days after new Moon), I often noticed that the earthshine becomes noticeable near the end of civil twilight, and very noticeable during ...
2 votes
1 answer
199 views

Why are most cosmic rays positively charged? Has anyone figured this out yet?

It is by now very common knowledge that the vast majority of (known) cosmic rays are protons, alpha particles and such, yet I cannot find in my recent reading any discussion of why this might be, or ...
1 vote
2 answers
2k views

Why isn't a month 28 days?

1 days is a rotation of earth. 1 years is an orbit of the sun. I've always beleived that one month is 1 period of the moon orbiting earth but the inconsistent distribution of days throughout the ...
3 votes
1 answer
3k views

Why does time pass faster in moon than the earth?

One of my friends said that, time passes faster in moon than the earth Why does time pass faster on the moon than on the earth?
2 votes
1 answer
107 views

Are there any softwares which help in simulating different experiments regarding flight of aircrafts on different terrestrial planets of solar system?

I have a few experiments on aircrafts whose results I am aware of if performed on the earth's surface. However, I am searching for software(s) that can help simulate the same or other experiments on ...
2 votes
3 answers
232 views

What does the rate the Moon moves away from Earth depend on?

Is it based on the distance between the Earth and Moon? Would that make the Moon move away faster or slower as time goes on?
14 votes
8 answers
5k views

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 ...
1 vote
1 answer
71 views

Will the Earth tidally lock to the Moon (ignoring Sun's expansion)

At some point, won't the tidal forces from the Moon be less than the ones from the Sun? Would that mean that the Moon stops moving away, or would the process still continue. Would the Earth start ...
5 votes
1 answer
234 views

How will the Solar tides affect the Earth's rotation once it is tidally locked to the Moon?

It is my understanding that the tidal forces of the Moon acting on Earth cause it to slow down its rotation and, because angular momentum is conserved, the Moon's orbit subsequently expands. This ...
12 votes
1 answer
2k views

Would the Earth and Moon still have tides after the Earth tidally locks to the Moon?

Ignore the Sun's expansion. From my understanding, tidal locking happens from torque as a result of tidal bulges being offset from the line between the two planets. So when the Earth and Moon tidally ...
1 vote
1 answer
102 views

How far should we be from Earth to see a half Moon while it is seen as a crescent on the Earth?

When we see a crescent Moon that means it should be seen a half Moon from another position in the sky, because the terminator line (i.e. the line that separates the bright and dark areas of the Moon) ...
11 votes
2 answers
5k views

What would happen if Venus and Earth collided?

The first thing we would need to consider is that Earth has already been hit by a protoplanet half its size 4.5 billion years ago, meaning the Earth may have a chance of staying intact after the ...
3 votes
0 answers
74 views

To what extent does the increased average airmass the Sun's light passes through contribute to the seasons?

The traditional explanation for the cause of seasons I have heard is that because of the angle of the axis of the Earth with respect to the ecliptic, the angle at which light rays hit the Earth's ...
2 votes
0 answers
114 views

If the distance from Earth to the Sun was filled with air, how loud would the sun be?

Based on this question: If there was air between the Sun and Earth, how warm would we get? Many sources state that if sound wasn't limited by matter, we would hear the Sun at around 100dB constantly, ...
-1 votes
1 answer
135 views

Whis my planetary volume formula wrong? (volume = mass/density)

I'm having trouble with this and am unsure what I'm doing wrong. Let's use Earth as an example. Earth has a mass of 5,972,168,000,000,000,000,000,000 (5.97E+27) kg and a density of 5513.4 kg/m3 or 5....
4 votes
3 answers
590 views

Is this definition of tidal locking really satisfying?

We always are hearing this: "If a moon has equal rotational and orbital periods it's tidally locked to its host planet and always one side of it will face to the planet." But what if, for ...
3 votes
2 answers
487 views

How did Ptolemy prove in the following excerpt that the Earth is not cylindrical?

I have trouble interpreting the following excerpt: “Nor could it [the Earth] be cylindrical, with the curved surface in the east-west direction, and the flat sides towards the poles of the ...
2 votes
1 answer
258 views

How does Ptolemy prove in the following excerpt that the Earth could not be outside of the axis spanning between the poles of the celestial sphere

I have trouble interpreting the following excerpt: “Against the first of these three positions militate the following arguments. If we imagined [the earth] removed towards the zenith or the nadir ...
2 votes
3 answers
2k views

What effect does Earth losing a part of its mass have, is there an impact on the Earth's orbit around the Sun?

This is a random question that popped into my mind. I'm not a physicist or astronomist, however, I am genuinely curious. Also, this is not intended as a science fiction question, but an actual science ...
4 votes
2 answers
4k 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: I have some questions: Does the earth spiral around the sun's path as it is ...

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