How Far Up Do You Need to Go to Escape Earth's Gravity?

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Discussion Overview

The discussion revolves around the concept of escaping Earth's gravity, specifically addressing how high one must travel to no longer be influenced by it. Participants explore various altitudes, including 100 km and 1000 km, and the implications of the Kármán line in relation to gravitational effects. The conversation includes questions about the nature of gravity and its influence on objects at different altitudes.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants question whether traveling 100 km or 1000 km vertically would result in floating away from Earth's gravity, with varying opinions on the influence of mass at these altitudes.
  • There is a discussion about the Kármán line, defined as the boundary between Earth's atmosphere and outer space, and its relevance to gravitational effects.
  • One participant mentions that gravity is infinite and affects all mass in the observable universe, though its influence diminishes with distance.
  • Another participant argues that the Kármán line is related to atmospheric density rather than gravity, suggesting a misunderstanding of its implications.
  • Some participants express confusion about the relationship between altitude and gravitational influence, with references to the Moon's orbit as a point of clarification.
  • There are corrections and challenges to earlier claims regarding gravity's effects at different altitudes, indicating a lack of consensus on the topic.

Areas of Agreement / Disagreement

Participants do not reach a consensus on how high one must go to escape Earth's gravity, with multiple competing views and ongoing debate about the implications of the Kármán line and the nature of gravitational influence.

Contextual Notes

Some statements reflect misunderstandings about gravity and altitude, and there are references to the dynamic nature of Earth's atmosphere that complicate the discussion. The conversation includes various assumptions about mass and gravitational influence that remain unresolved.

gugicas
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If we travel 100 km vertically from the surface of the earth, will we no longer be pulled by Earth's gravity and float into space? Same question as above yet with 1000 km. How far up vertically do we have to go to escape Earth's pull and how wide/long is the Earth's gravitational influence. Does an object stop being affected by Earth's gravity after it crosses the karman line if its mass is to small.
Im sorry for so much questions but if you could answer them all id be eternally grateful.
 
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What do you think? And why?

Here's a starter: What keeps the Moon going around Earth every month?

Question: what is a karman line? I am not familiar with this term.
 
Another hurdle to strictly defining the boundary to space is the dynamic nature of Earth's atmosphere. For example, at an altitude of 1,000 km (620 mi), the atmosphere's density can vary by a factor of five, depending on the time of day, time of year, AP magnetic index, and recent solar flux.[citation needed]

The FAI uses the Kármán line to define the boundary between aeronautics and astronautics:[7]
 
Technically, gravity is infinite. You feel gravity from every single thing in the "observable" universe. You'll certainly never notice almost all of it, but it's there. Since it propagates at light speed, anything beyond "observable" won't yet be felt. (But someday... brace yourself. :D)
 
Danger said:
Technically, gravity is infinite. You feel gravity from every single thing in the "observable" universe. You'll certainly never notice almost all of it, but it's there. Since it propagates at light speed, anything beyond "observable" won't yet be felt. (But someday... brace yourself. :D)
I think it would have been more helpful to the OP if you had waited for him to answer Dave's question, and thereby think about the issue himself, rather than spoon feeding him the answer yourself.
 
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phinds said:
spoon feeding him the answer yourself
I deliberately avoided that by making no mention of what constitutes a "gravitational well" which is what the question was about. Mine was a hint, not an answer.
 
jerromyjon said:
Another hurdle to strictly defining the boundary to space is the dynamic nature of Earth's atmosphere. For example, at an altitude of 1,000 km (620 mi), the atmosphere's density can vary by a factor of five, depending on the time of day, time of year, AP magnetic index, and recent solar flux.[citation needed]

The FAI uses the Kármán line to define the boundary between aeronautics and astronautics:[7]
That's irrelevant when just dealing with the effects of gravity

Lets wait for the OP to answer DaveC's questions
 
DaveC426913 said:
What do you think? And why?

Here's a starter: What keeps the Moon going around Earth every month?

Question: what is a karman line? I am not familiar with this term.
Sorry for the late reply i posted this late at night. About
that question i think if you travel a 100 km up or even a 1000 km up you would fall back to Earth since you are still in its hill sphere and still in under its dominant gravitational influence. But a teacher of mine said that if we travel a 100 km up(person only no spaceship) that we would float into space since Earth's gravity only affects objects with such a small mass under a 100 km radius.
 
hi quqicas

OK now answer/comment on the second sentence in DaveC's post that you quoted

gugicas said:
But a teacher of mine said that if we travel a 100 km up(person only no spaceship) that we would float into space since Earth's gravity only affects objects with such a small mass under a 100 km radius.

I don't think you worded that quite right ;)
try again
 
  • #10
DaveC426913 said:
Question: what is a karman line? I am not familiar with this term.
The Kármán line is the boundary between Earth's atmosphere and outer space. It lies at 100km(62mi) above sea level
davenn said:
I don't think you worded that quite right ;)
try again
Sorry for that xD. A professor at my high school said:"If a person goes 100 km above sea level, he will float off into space because Earth's gravity only affects things with such a small weight up until 100 km line(Karman line). When he crosses that line he will float off into space because he wouldn't be affected by Earth's gravity". Edit: Forgot the apostrophe.
 
  • #11
gugicas said:
If a person goes 100 km above sea level, he will float off into space because Earth's gravity only affects things with such a small weight up until 100 km line(Karman line). When he crosses that line he will float off into space because he wouldn't be affected by Earth's gravity". Edit: Forgot the apostrophe.

The Karman has nothing to do with gravity and floating off into space
its to do with the thickness/density of the atmosphere its ability to be able to support aerodynamic lift

so let's get back to gravity

again I ask you to ...
OK now answer/comment on the second sentence in DaveC's post that you quoted

cheers
Dave
 
  • #12
The moon orbits around the Earth because of Earth's gravity.
 
  • #13
gugicas said:
The moon orbits around the Earth because of Earth's gravity.
But you just said that anything over 100km up would float off ... do you think the moon is closer than 100km?
 
  • #14
gugicas said:
The moon orbits around the Earth because of Earth's gravity.

yes that's correct ... well partly ... the moon has gravity as well, so its a mutual gravitational attraction between the 2 of them

So now answer phinds's question,

so maybe now you are starting to see the problems with your initial comments ;)
 
  • #15
gugicas said:
If we travel 100 km vertically from the surface of the earth, will we no longer be pulled by Earth's gravity and float into space?
Have you even tried a web search for "earth gravity", before posting? The first hit is this:
http://en.wikipedia.org/wiki/Gravity_of_Earth

With this nice graph:

Erdgvarp.png
 
  • #16
Well sorry for pestering you guys, but thanks for these answers. I got it now.
 
  • #17
gugicas said:
Well sorry for pestering you guys, but thanks for these answers. I got it now.
Your questions were not pestering. That's what this forum is here for, to clear up this kind of misunderstanding.
 
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  • #18
gugicas said:
got it now.
Good. Then explain it to your teacher, if he/she really said this stuff.
 

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