Questions regarding the planet on which humans live, the third planet from the sun.

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5
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3answers
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Does the Sun impose back it's tidal forces onto the Earth (such as the Earth's to the Moon)?

It is known that each year the Moon is moving away from the Earth due to tidal forces. What about the Earth relative to the Sun?
5
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1answer
793 views

How many earths fit in the observable universe?

I was pondering our insignificance, when I wondered - how how much smaller is our planet then the (observable) universe? And being as I dont know how to do the math, I'm asking it here. So how many ...
11
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4answers
3k views

Is the Earth going to evolve towards Mars' fate or Venus' fate?

Upon reading on this site (and many others), one can think that Mars might have supported life in a distant past (discovery of liquid water, valleys, mountains...). On the other hand, Venus is the ...
4
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3answers
109 views

Why wasn't there any oxygen in the beginning of the earth?

In the total beginning of the earth there was CO2, N2 and H2O. So there was O2 but always in bond with Carbon and hydrogen, but what is the reason for that? Is O2 always reacting with free ...
1
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0answers
63 views

are modern flat earthers still believe the earth is flat not round? [closed]

I saw a video in youtube and read few articles about how flat earthers believed that earth is actually flat but not round. They even presented facts about how everything which is true right now is ...
1
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1answer
53 views

What is the distance of earth from 7 planets, moon and sun at a point of time?

I wanted to know the distance of the 7 planets(mercury, mars, venus, jupiter,saturn, uranus, neptune) each (or at least 5 planets) from the earth and the angle that it will make with a line connecting ...
7
votes
1answer
110 views

Why don't storms on gas giants move to the poles, like hurricanes on Earth do?

On Earth, hurricanes usually move from the equator to the poles. But if you look at a picture of Jupiter, you'd see that the Great Red Spot isn't anywhere near the poles. So the question is: why don't ...
-6
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0answers
83 views

How old was “student-Earth” when life first formed? [closed]

this section is meant to explore the relative timings of various important events in Earth's history by re-imagining Earth as a 20-year student. You will need to scale geologic time from the age of ...
5
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2answers
297 views

Can I look at the sky and find the day of the week?

Suppose I wake up from a coma on a desert island in the 19th century (i.e. we already use the Gregorian calendar but have no satellites yet). I have a clear view of the sky and a couple of days to ...
2
votes
3answers
130 views

Closest point on Earth to a planet?

I'd like to be able to find the latitude and longitude on Earth (assuming a sphere is fine) which is closest to Pluto at the current time (or where Pluto is directly overhead). Is this possible with ...
5
votes
1answer
170 views

How can one explain the apparent motion of the Sun from a heliocentric point of view?

From a horizontal frame of reference, the path of the Sun looks like a part of a circle in a tilted plane, as shown in this picture: ...
2
votes
1answer
110 views

If the Sun got larger, but maintained its luminosity, would the Earth get hotter or colder?

A recent question If the Sun were bigger but colder, Earth would be hotter or colder? asked - if the Sun got bigger and cooler, would the Earth heat up or cool down. I think the answer to that is ...
8
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2answers
194 views

Why does this graph for sunlight intensity on land has a steeper slope during sunrise as compared to sunset?

I got this image while checking weather data for a city in North India using Mathematica's Wolfram Alpha query I noticed one feature in the graph which i could not explain . Why does the encircled ...
1
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4answers
91 views

What do we mean by Sunrise and Sunset?

If the Earth rotates on its own axis, then what do we mean by sunrise and sunset?
4
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1answer
61 views

Sun as our Supergiant

Let's talk about the time when our sun becomes a supergiant. We know that our solar system may get destroyed or it may get affected due the large mass of the supergiant and also due to the large ...
0
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2answers
78 views

What is the future of our universe?

Is the universe heading towards a Big Freeze, a Big Rip, a Big Crunch or a Big Bounce? Or is it part of an infinitely recurring cyclic model?
0
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0answers
32 views

What is the shape of the Sun's orbit around the Earth taking into account elliptical orbits?

Consider the non-inertial frame that is at rest with respect to the Earth's revolution around the Sun. (Ignore the Earth's rotation around its own axis.) My question is, what is the shape of the ...
0
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3answers
91 views

Why is it that we can"t feel how fast the Earth is moving? [closed]

We are moving like 100,000 mph. And why do we not fall off going that fast
2
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1answer
68 views

Are there accurate equinox and solstice predictions for the distant past?

I am trying to find information on the equinox/solstice dates before 1600, more exactly referring up to 10,000 BCE so as to create a sort of calculator on an Excel spreadsheet. I have read about the ...
5
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4answers
178 views

22nd is shortest day in some places, but the 21st is shortest in other places. Can this be true?

The Winter Solstice in the Northern hemisphere in 2015 is December 22 at 04:49 UTC. Where I'm located in Nova Scotia, Canada, that's December 22, 00:49 AST. And so I would say the shortest day of ...
1
vote
3answers
36 views

Is the duration of a sidereal year stable?

According to this essay by Phil Plait, the duration of Earth's sidereal year is 31,558,149 seconds. Is this figure stable? If I were to meaure Earth's orbit several million (or billions) of years in ...
9
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3answers
3k views

Why isn't Earth a perfect sphere? [closed]

In general, almost everyone describes Earth as an perfect sphere, but in reality it isn't a perfect sphere. Is there any specific reason why Earth is not perfect sphere ?
64
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2answers
7k views

How loud would the Sun be?

Sound can't travel through outer space. But if it could, how loud would the Sun be? Would the sound be dangerous to life on Earth, or would we barely hear it from this distance?
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2answers
183 views
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1answer
124 views
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0answers
45 views

Earth-Centered Earth-Fixed coordinates with respect to heliocentric coordinate system at vernal equinox

I am trying to calculate the position of a point on the Earth's surface with respect to the Sun's center at certain date at time. For what I am trying to do it is OK to ignore precession of Earth's ...
1
vote
2answers
97 views

Can earth escape sun's gravity with the help of a black hole heading towards our solar system?

To escape the Sun's gravity, the Earth would need sufficient amount of energy. Let's say a stellar black hole has entered our solar system and at a certain distance from earth, the black hole exerts ...
9
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3answers
3k views

What if Earth and Moon revolved around each other like Pluto and Charon?

What would be different for us if Earth and Moon revolved around each other like Pluto and Charon do?
13
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2answers
2k views

How many planets have we discovered that can support human life?

I have heard a lot of buzz about distant planets that could potentially be second homes for human existence, but what is that approximate number?
4
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1answer
75 views

Why would the Earth's solar analemma would be still a figue eight even if Earth's orbit was circular?

The Earth's solar analemma is a diagram showing the deviation of the Sun from its mean motion in the sky, as viewed from a fixed location on the Earth. ... For [a planet] with a circular orbit but ...
4
votes
1answer
89 views

Ambiguity in Earth's “Tilt”

It’s well-known that the axial tilt of the Earth (with respect to the ecliptic) is about 23.4 degrees. However, two angles is needed to specify the orientation of any rigid body, so it’s unclear to me ...
13
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3answers
4k views

Why does the Earth have a tilt of ~23°?

Is there a reason that the Earth has the tilt that it does (~23°)? How do we know which way is supposed to be 0°? Does this tilt have major consequences on the planet? Has it changed and will it ...
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0answers
70 views

Does the mass of the Earth change?

Every day, babies are born and people grow, which makes their respective masses greater. However, this change in mass (should) come out of the food that they consume - it is used as energy and thus ...
11
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2answers
2k views

Is Earth unique in its fairly clear atmosphere?

So, we have surface pictures from two alien planets, Venus (captured by the Venera 13), and Mars (captured by the rover). Both of these pictures appear to be very dusty. For Venus we see strong ...
2
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2answers
190 views

Precessing of the Earth

It's been known that the Earth's axial tilt varies from 22.5 to 24.5. Does this result in a wobbling while the value of the tilt varies about these two limits? If so, how does it affect the mechanics ...
6
votes
4answers
457 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: ...
4
votes
1answer
138 views

If an Asteroid was to strike the Earth, would it affect the Earth's rotation?

If an Asteroid was to strike the Earth, would it affect noticeably the Earth's rotation, and if so, how large would this Asteroid have to be?
2
votes
1answer
41 views

Math for calculating the terrestrial longitude directly under the sun with time

I'm trying to calculate the longitude on the earth where it's noon at some time. (That is, the longitude which is coplanar with the plane defined by the sun and the earth's axis.) Here is my python ...
-5
votes
3answers
214 views

The end of the Earth and human history [closed]

If you think that we born on 1920...2000 and knows that the sun will explode 4 to 5 billion years from now. you will say that the time is a strange thing. I can not say that i will die before i know ...
0
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2answers
93 views

Tidal lock of earth and moon

As the Moon is tidally locked to Earth, that means, from Earth we can only ever see one side of the moon. Can we see all the sides of the Earth, from the moon?
3
votes
0answers
76 views

Does Mars contain more iron than the Earth?

Is the reason Mars is red because its surface contains a lot of iron? (When dirt is red on Earth, it is sometimes caused by a high amount of iron). If so, does Mars contain more iron than the earth? ...
37
votes
4answers
5k views

How does the Earth move in the sky as seen from the Moon?

I just want to be sure I am visualizing this correctly, because it seems odd. The Moon is tidally locked to the Earth but there are wobbles to its motion due to libration. So from a point on the ...
3
votes
1answer
4k views

Average amount of annual daylight at any place on earth

If this is the wrong group please direct me to the correct one. It seems intuitively obvious that the amount of daylight per annum should be the same for any latitude on earth. For example, 12 hours ...
6
votes
4answers
433 views

Does Sun have a reflection on Earth?

The new Google Maps1 presents an actual view of Earth, with the current position of Sun illuminating half part of Earth in real time. It is quite an exquisite view. My question is based on the ...
5
votes
2answers
243 views

If we found evidence of life on Mars, how would we know that it originated on Mars rather than Earth?

Consider this scenario. One of the probes sent to Mars either very soon, or within the next century, finds conclusive micro-fossil evidence that life once existed on Mars. One theory today that is ...
2
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1answer
95 views

What light source can cause a shadow of a cloud onto the next cloud above?

Scenario- -Time & Environment-11:00pm Super Moon small town population 40,000 in Central Ca. -Nearest body of water is 80 miles away 4 small lakes of about 1 mile in diameter. -Pacific Ocean is ...
1
vote
3answers
227 views

Where exactly does the Moon flip, given that it appears the other way up in the other hemisphere?

I've read in multiple sources that the Moon appears the other way up in Northern Hemisphere vs Southern Hemisphere. Here is one that explains why: Does the Moon look different in the northern and ...
9
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5answers
419 views

What will a lunar eclipse look like from moon?

What will a lunar eclipse look like from moon? Will earth become a completely dark circle?
4
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2answers
75 views

Understanding Earth Tilt, Sun's Position and Lattitude Calculation

I've been trying to figure out how to calculate the latitude of my location with just the shadow of a stick cast by the sun. I am doing this under the assumption that I am stranded in some place with ...
7
votes
3answers
169 views

Why Earthian atmosphere is so thin?

Venus is somewhat lighter then Earth, yet has a much thicker atmosphere. One would imagine that the following should be true: During the formation phase, all inner planets had captured as much gas ...