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

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1answer
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Orbital Elements Transformations

I'm a third year undergrad, and for the project I'm doing this summer, I need to figure out the Earth's position and velocity from the moon's point of view. From the reading I've done, it seems like ...
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1answer
472 views

How likely and severe is the threat of a gamma ray burst to earth?

In the National Geographic article: http://news.nationalgeographic.com/news/2009/04/090403-gamma-ray-extinction_2.html it is suggested that a gamma ray burst likely caused a mass extinction in earth's ...
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1answer
57 views

Did the Babylonians believe in the Heliocentric version?

It's mentioned that the Babylonians decreed that there were exactly 360 days in a year. This statement was based upon the utilization of 360 as a standard (based on the sexagesimal system) i.e., they ...
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4answers
811 views

Did we ever actually see the earth revolving around the sun? Is the geocentric model completely disproved?

Did we ever actually see the Earth revolving around the Sun? Also, is the geocentric model completely disproved or was it sidelined because the heliocentric model made things easier to understand? ...
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2answers
290 views

How to calculate right ascension of Greenwich? [closed]

If I know specific time, t0, how can I calculate RA of Greenwich?
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2answers
165 views

Does Earth revolves around Milky Way?

As we know Earth rotates around Sun and Sun around Milky Way but then Sun must have some velocity/angular momentum (I don't know that much physics terms). So as Earth revolves around Sun, it must ...
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1answer
338 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 ...
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1answer
158 views

Calculate Day of the Year for a given date

I am trying to make sense of the following formula that claims to calculate the day of the year given today's date represented by (day/month/year): ...
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2answers
2k views

If Earth didn't rotate, would we feel heavier? [closed]

Suppose the Earth's rotation slowed for some reason. Would the lack of centrifugal force cause us to feel heavier than normal? Likewise, if Earth's rotation increased, would we feel lighter as ...
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3answers
502 views

Is it a coincidence that both the sun and moon look of same size from earth?

The sun is huge when compared to moon. Despite the huge difference in their size and distance from earth, Is it purely coincidental that they both look almost the same from earth?
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4answers
259 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?
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1answer
122 views

Why is every year the same number of days despite the gravity in the solar system?

I was just watching a Geoff Marcy talk on YouTube showing how they infer the presence of planets transiting distant stars. The supposed periodicity wasn't always quite regular from what I could see, ...
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4answers
500 views

Why don't we feel the speed of earth moving

When we move our vehicle, we "feel" the speed of it. However, when stationary, we still are moving,but moving by quiet a speed. We know that earth moves with X ...
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2answers
481 views

What mechanism causes oscillations of the solar system's orbit about the galactic plane?

In a recent paper (news release here) Lisa Randall and Matthew Reece propose that a dark matter disk coinciding with the galactic plane together with the solar system's oscillations through the ...
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1answer
123 views

Radioactive decay is the main source of the earth's interior heat: fact or theory? [closed]

It's believed the main reason that the interior of the Earth hasn't cooled down in 4 billion years is because of the ongoing decay of radioactive elements that keeps adding more heat than is lost to ...
2
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1answer
114 views

Why doesn't the earth's surface collapse onto itself? [closed]

From what I know the sun (or any other star) nuclear fission keeps it from collapsing under its own gravity until the fuel runs out, if that's so why doesn't the earth surface like the tectonic plates ...
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2answers
70 views

regarding curvature of earth [closed]

i am having one doubt in earth's curvature.....this question may be dumb... How much we need to travel on earth to feel the curvature of earth. hypothetical case: for ex we are building a vehicle ...
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2answers
169 views

What would happen if we put a small part of White Dwarf or Neutron Star on Earth?

I would know what would happen if we put a small part (let me assume 1 cm$^3$) of White Dwarf or Neutron Star on ...
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2answers
418 views

Why haven't Earth and Venus got any tiny moons? Or have they?

Why haven't some meteoroids gotten caught in Earth's or Venus' orbit? AFAIK most meteors are tiny fragments from comets. Shouldn't some comet tail sometime have passed Earth orbit at velocities ...
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2answers
70 views

Would it be possible to calculate the expected frequency of impact craters of all sizes on Earth

Can the expected frequency of all sizes of impact craters on Earth be calculated based on the preservation of impact craters seen on the Moon? Taking into account the difference in gravity and ...
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2answers
230 views

If the earth stopped rotating, would we really fly inertially at 1000mph? [closed]

I heard this on Prof. Neil Tyson's StarTalk podcast (this episode) and had a question about it. In a Q&A session, a listener had asked what would happen if Superman really did stop the earth from ...
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1answer
406 views

If the tilt of the Earth changed, would the tropics latitude change too? [closed]

I wanted to know if the tilt of the earth were changed to 30 degrees would the tropics of cancer and Capricorn also both change to 30 degrees?
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2answers
3k views

Why don't stars move in the night-sky as the moon does?

I want to know why don't we see a change in the position of stars during the night while we do see a change in the position of the moon. I've checked other online sources and some answers say that it ...
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1answer
260 views

What distance has the moon been from earth at the closest?

For every year, the moon is orbiting further away from earth. What distance has the moon been from earth at the closest?
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3answers
344 views

Are we made of the stuff of one star or more stars?

[T]his coincidence enabled stars in the late stages of their lives to turn helium into carbon, oxygen and most of the other atoms that you and I are made of. [...] [W]e're made of star stuff. Max ...
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1answer
330 views

Latest sunrise/earliest sunset out of phase with solstice?

Everybody knows that the shortest and longest days of the year occur on the solstices. However, examination of sunrise/sunset tables shows that the maxima and minima of sunrise/sunset times are ...
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1answer
175 views

Could something temporarily break the Moon's tidal lock?

Would it be possible for something to cause the Moon to start rotating at a different rate, breaking its tidal lock with Earth, without ripping it apart? If so, would the Moon's tidal lock eventually ...
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2answers
699 views

What is the Exact time earth takes to revolve around its axis [closed]

I read that our day is not exactly 24 hours long. If it is not then why weather seasons come at the same time (Summer, Winter, Autumn Spring) ? how it is equalized ? Update: Sorry I could not make ...
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0answers
36 views

Why the earth revolves? [duplicate]

Why do the earthor any other planet continue to revolve around the sun or a star in general and that also with constant time period?What is the reason behind it?Other than gravitational force is ...
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1answer
237 views

How stable are Lissajous orbits?

Now that the Gaia Space Telescope is on it's way to the Sun-Earth L2 Lagrangian point (SEL2), I start wondering about the stability of Gaia's orbit there. The Planck Telescope is already there, as was ...
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1answer
121 views

Did a piece of Halley's comet strike the Earth 1,500 years ago?

A friend showed me an article saying that there's evidence that a piece of Halley's comet may have struck the earth about 1,500 years ago. Is anyone here aware of such evidence?
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6answers
868 views

Why don't we have 2 Summers and 2 Winters?

Due to Earth's elliptical orbit, its distance from Sun varies by almost 5 million Kilometers (147 million Kilometers at closest point & 152 million Kilometers at farthest point, i.e. almost 3% of ...
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3answers
412 views

How can the Earth's rotation speed up? [closed]

It is known as a fact that Earth's rotation is slowing every year, that's why we sometimes have 61 seconds long minutes. In the Java documentation of Time : ...
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1answer
50 views

Is there a pattern between the mass of a body and the mass of orbiting objects around it?

I was looking at Wikipedia's Solar system page, and it says that Sun represents 99.86% of the whole solar system mass. I found that pretty huge. So i calculated ratio of masses : Earth / (Earth + ...
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1answer
440 views

How do people measure the distance between the earth and the moon?

How do people measure the distance between the earth and the moon? What methods were used? Where can I find the official data?
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1answer
449 views

Could any known, living organisms on Earth survive on Mars?

No life has been discovered outside of Earth (yet?), but do we know if anything that would be considered "living" on Earth could conquer Mars? (or maybe Venus?) With the Mars One project on the way, ...
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2answers
192 views

Could Venus be a source of Earth's water?

I've watched documentaries about the solar system, where it is suggested that Venus once had oceans of liquid water similar to those that cover most of Earth today. Venus is now in a period of ...
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2answers
4k views

What is the distance that the Moon travels during one orbit around the Earth?

Also, does it always take the same amount of time, or does it fractionally differ on each revolution?
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0answers
265 views

What effect does the Earth's rotation have on plate tectonics? [closed]

I've been reading up on plate tectonics and found that there are several different driving forces involved. One of the main categories of driving force mentioned on Wikipedia is forces related to the ...
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1answer
4k views

How would Earth's climate differ if it's axis were tilted around 90 degrees like Uranus? [closed]

As the title states, what would the effect on Earth's climate be if it's axis were tilted approximately 90 degrees like Uranus? I'm specifically wondering about the effects on seasons, temperature, ...
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1answer
171 views

Changes to Earth's orbit

Any time a spacecraft comes in close proximity to a planet and if the spacecraft has the right angle then it is able to use the planet's velocity to move itself further into space. According to ...
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1answer
444 views

How much of an effect does the moon have on Earth's liquid mantle?

The gravitational pull of the moon is enough to create tidal forces of large bodies of liquid, i.e the sea. I was having a conversation the other day about how to terraform Mars, and someone ...
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2answers
212 views

Why is the Earth's center still hot after millions of years? [closed]

Why didn't the center of the earth cool after millions or billions of years? What keeps it hot?
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0answers
158 views

Day and night temperature on an earthlike planet with longer rotational period [closed]

I'm trying to understand the climatic effects of the far future scenario of an Earth-like planet with a reduced rotational speed caused by tidal locking with the moon (day-night period of 28 days, one ...
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2answers
1k views

Does the Moon's magnetic field affect Earth's magnetic field?

I wanted to ask a question; it's simple but I cannot find any possible and perfect solution. Earth has poles, North and South. By which we can get directions using a compass or a needle compass, but ...
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1answer
136 views

Were effects of a planetary magnetic field reversal observed on other planets than Earth?

From geological records in rocks and minerals we know that the magnetic field of Earth changed its polarity multiple times in the history. See Geomagnetic reversal. Was a similar process of a ...
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2answers
1k 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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2answers
169 views

How often does Earth cross the galaxy regions with higher supernovae activity?

According to Summa Technologiae, a book by a Polish author Stanisław Lem that based his science fiction novels on scientific research of the era, the Earth crossed in the moment of forming of life the ...
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1answer
72 views

Earth and ferromagnetism [closed]

Earth's core is a giant liquid iron ball actually. If I know well, the magnetic field of our planet (that protects the surface from some particles comes from the Sun) can exist because as Earth ...
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3answers
2k 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 ?