Questions tagged [earth]

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

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16 votes
2 answers
5k views

Why is there a year 1 B.C., a year 0, and a year 1 A.D. in NASA’s Five Millennium Canon of Solar Eclipses?

I was looking through NASA’s Five Millennium Canon of Solar Eclipses, and I am really confused by the fact that there is a year -1, 0, and 1. I was always taught that there was no year 0, that we just ...
-1 votes
0 answers
65 views

Does the minus sign in the path width section on NASA’s Five Millennium Canon of Solar Eclipses have any meaning?

I was looking through NASA’s Five Millennium Canon of Solar Eclipses and I am a little confused by the notation for several. In the “Path Width” column, 87 entries have a “-” in the cell. To be sure, ...
0 votes
0 answers
26 views

Is there a known magnitude of the sun that needs to be covered for the diamond ring effect or Bailey’s beads to occur?

During a total solar eclipse, there is this brief, roughly 1-20 seconds during which some absolutely incredible, indescribable phenomenon occurs. It was the most beautiful thing I have ever seen. They ...
0 votes
0 answers
29 views

Is it possible for both transition points in a hybrid eclipse to occur so close together they can be seen from the same spot on earth?

There are 4 categories of eclipses. There are partial, annular, total, and hybrid eclipses. In a partial eclipse, part of the moon covers the earth casting its penumbra on earth. Judging from my ...
0 votes
0 answers
22 views

Is there any way to know how much time of totality is experienced during a hybrid eclipse in NASA’s 5 Millennium Canon of Solar Eclipses?

I was just looking through NASA’s 5 Millennium Canon of Solar Eclipses. It’s really a fantastic list, having the max time of totality and all. I was trying to figure out what the maximum amount of ...
3 votes
1 answer
478 views

Measure the radius of the earth using the sun?

Can someone tell me why this would or would not work? I have a sun spotter device that projects an image of the sun onto a piece of paper using a lens and some mirrors. When you use the device it’s ...
1 vote
0 answers
49 views

Moon mass object hitting Earth vs Moon mass blackhole hitting Earth damage comparison

Doesn't a blackhole do less damage if it goes fast enough to be able to escape fast enought but a moon-mass object if going faster does more damage? Is this true or would a black hole do more damage?
8 votes
1 answer
98 views

Does polar motion cause the Earth ellipsoid to change?

The Earth is oblate because it spins and is not a rigid body. Since its spin axis changes relative to its crust, then the meridian of maximum diameter changes too, right? I understand that polar ...
2 votes
1 answer
262 views

What would the night sky look like after 200 years?

It is research for a book I am writing. The year is 2200. Assume the volume of items in orbit has increased dramatically from today’s numbers. We go to war and blowup all the satellites. Four hundred ...
3 votes
2 answers
620 views

Will Earth become a gas giant when the Sun expands in 5 billion years?

Because if the Sun expands to 1 AU or very close to it, its density and hold on outer layers will be much weaker so a dense object like the Earth can slowly absorb material because Earth would be much ...
0 votes
0 answers
43 views

How to find the Moon's node longitude crossing

Yes, I asked this in the past but I got sidetracked and did other things. Now my question is, can one find the exact time when "north node" reaches a certain longitude? I am looking for 15....
14 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
229 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
22 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
123 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
143 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
183 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
153 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
587 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
109 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
13k 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
107 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
112 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
439 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
138 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 ...
15 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
189 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
213 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
863 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
214 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
149 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
151 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
201 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
4k 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
259 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
235 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 ...

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