# Questions tagged [earth]

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

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1 vote
79 views

### How quickly would these changes happen if the moon were to suddenly disappear?

There's a lot of articles and videos on the topic of what would happen if the moon were to suddenly disappear. Two consequences that seem to come up often are an increase in variation of Earth's axial ...
130 views

### Why when i divide the distance of sun to earth by golden ratio, the result starts with the last 5 digits of speed of light? [closed]

When i divide 149597870700m:1.618, i get (92458)510939, the last 5 digits of speed of light, 2997(92458)?
81 views

### Calculating lunar parallax based on a distance between two objects at certain latitude

I want to compute lunar parallax based on the distance between two points. In fact I know the formula, but I guess they're explained wrong. By looking at the image below we can see the polar radius, ...
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### What can be learned from viewing the sun on earth during a total eclipse that cannot be studied by spacecraft in orbit?

I understand that total eclipses are a fantastic time to study the sun's corona, and the reason for this is because the much brighter photosphere is blocked by the moon. But, couldn't the Parker solar ...
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### Why is the terminator line not orange-red in photos from space?

As you know, the sun's rays at dawn and sunset are painted in golden-pink colors, and the objects on which they fall, primarily clouds, snow covers and water surfaces, are also colored. This happens ...
89 views

### Determination that the suns rays are parallel

How did Erastothenes and/or earlier scientist-philosophers determine that the sun's rays arriving at the earth are parallel? Atmospheric and perspective effects would have suggested otherwise. He used ...
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1 vote
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### What is the difference between a solar eclipse's (a) magnitude and the (b) moon/sun size ratio?

After watching a Smarter Every Day 2 YouTube video featuring Gordon Telepun, I purchased his ebook Eclipse Day 2024 and More off the Google Play store. In the book, he has a link to Xavier Jubier’s ...
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### Why does the projection-motion of the moon on the earth's surface have the shape of a sinusoid?

Why does the projection-motion of the moon on the earth's surface have the shape of a sinusoid? How does this fit with the tellurium model?
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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491 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 ...
56 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?
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### 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 ...
58 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....
• 167
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### 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 ...
• 607
247 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 ...
• 204
1 vote
26 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 ...
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### 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 ...
204 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 ...
• 321
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### 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 ...
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1 vote
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### 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 ...
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### 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 ...
249 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
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1 vote
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### 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.
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1 vote
170 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 ...
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1 vote
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### 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 ...
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### 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 ...
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### 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
260 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 ...
257 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 ...
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### 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 ...
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### 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 ...
157 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 ...
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1 vote
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### 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 ...
• 147
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### 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 ...
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1 vote
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### 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 ...
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### 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?
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### 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 ...
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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 ...
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1 vote
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### 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) ...
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 ...
75 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 ...
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### 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 ...
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### 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, ...
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### 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....
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### 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 ...
685 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 ...
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