# Thread: Why!, do the Sun and the Earth not colllide?

1. Gravity is a pulling force to matter?

the earth has gravity a pulling force, and also the sun has gravity a pulling F.

So why do we not just collide, what F , stops us colliding?

2.

3. The Earth isn't falling towards the Sun because the Earth is moving sideways in relation to the Sun. If the Sun (and the rest of the Solar System!) wasn't there, the Earth would move in a straight line. The gravity of the Sun bends that straight line into a line that curves around the Sun. So, the Earth is falling around the Sun, due to the gravity of the Sun.

Don't think of gravity as a force that pulls. Think of it as something that bends the straight lines that things fall along.

If you simply release an object above the Earth, it falls straight towards the Earth. If you give it a little sideways motion when you release it, it will fall in a curve towards the Earth. But if you throw it hard enough sideways in relation to the Earth, it will miss the Earth completely and fall around the Earth. That is what we call an orbit.

4. In the early days of the solar system there were most probably many planets and planetoids flying all over the place.
Of these a bunch flew into the sun or each other and probably more flew out of the solar system.

so of all those the earth was one of those planets that was flying fast enough not to spiral towards the sun,
but not too fast to fly out of the solar system, it was along with the other planets we know of in a pretty balanced state between its speed and gravity'pull,
the same way satellites remain in orbit.

5. Originally Posted by SpeedFreek
The Earth isn't falling towards the Sun because the Earth is moving sideways in relation to the Sun. If the Sun (and the rest of the Solar System!) wasn't there, the Earth would move in a straight line. The gravity of the Sun bends that straight line into a line that curves around the Sun. So, the Earth is falling around the Sun, due to the gravity of the Sun.

Don't think of gravity as a force that pulls. Think of it as something that bends the straight lines that things fall along.

If you simply release an object above the Earth, it falls straight towards the Earth. If you give it a little sideways motion when you release it, it will fall in a curve towards the Earth. But if you throw it hard enough sideways in relation to the Earth, it will miss the Earth completely and fall around the Earth. That is what we call an orbit.
I have highlighted a quote from you, we are moving sideways relative to the sun because of the earths anti clockwise rotation? or ?

6. Originally Posted by icewendigo
In the early days of the solar system there were most probably many planets and planetoids flying all over the place.
Of these a bunch flew into the sun or each other and probably more flew out of the solar system.

so of all those the earth was one of those planets that was flying fast enough not to spiral towards the sun,
but not too fast to fly out of the solar system,
it was along with the other planets we know of in a pretty balanced state between its speed and gravity'pull,
the same way satellites remain in orbit.
Caught in a constant slingshot?

7. Because the sun's smart enough to know what a human infestation could do to its ecosystem.

8. Originally Posted by icewendigo
In the early days of the solar system there were most probably many planets and planetoids flying all over the place.
Of these a bunch flew into the sun or each other and probably more flew out of the solar system.

so of all those the earth was one of those planets that was flying fast enough not to spiral towards the sun,
but not too fast to fly out of the solar system, it was along with the other planets we know of in a pretty balanced state between its speed and gravity'pull,
the same way satellites remain in orbit.

Are you sure entire planets would escape the solar system at its early age? If that were the case why don't astronomers detect huge Jovian planets, or any planets for that matter in the interstellar medium. There's large asteroids and icy materials but I don't hear about many "planets" floating around outside of solar sytsems. If I'm wrong let me know. But I think if something as massive as a planet accretes inside a solar system, it likely won't go anywhere (outside the solar system) because the suns gravity has more of an attraction to things larger such as planets, and vice versa. I'm no physics expert however.

I agree a lot of crap left the solar system at an early age, but I doubt they ever had time to become planets. But please let me know if I'm wrong.

To discuss the question, not sure if anyone gave this example yet, but planets migrate inwards all the time in their solar systems. An example of this is the Jupiter like planets (Hot Jupiters) they found orbiting so close to its star. It's impossible it formed there due to the gaseous state its in, therefore the only way it got there is migrating inwards.
Link: Why 'Hot Jupiter' Exoplanets Aren't Eaten by Their Stars | Space.com

I think SpeedFreek gave a great answer to the question though.

9. Originally Posted by Cudamerica

Are you sure entire planets would escape the solar system at its early age? If that were the case why don't astronomers detect huge Jovian planets, or any planets for that matter in the interstellar medium.
Rogue planet - Wikipedia, the free encyclopedia

10. Originally Posted by Janus
Originally Posted by Cudamerica

Are you sure entire planets would escape the solar system at its early age? If that were the case why don't astronomers detect huge Jovian planets, or any planets for that matter in the interstellar medium.
Rogue planet - Wikipedia, the free encyclopedia

I stand corrected for that. But were they ejected during formation? Or during the star's main stage? Or can't we tell. Personally, I feel like if things were ejected during formation, they wouldn't have time to accrete into planets that fast.

11. Imo, just guessing, probably most things were ejected (or absorbed) early on, but then the odds a planet's orbit is exactly perfect down to the nanometer is small, it could get closer or farther by a few centimeter or meters or km per year or something. I can imagine an early planet that was getting farther away by hundreds of kilomerters per year, in which case after a billion years it would be billions of km away and no longer in orbit but drifting away where ever that puts it.

12. @icewendigo

But orbital speeds and distances don't have to be a "exactly perfect down to the nanometer" to orbit around the sun and not get absorbed. Look at comets from the oort cloud whose elliptical orbits are HUGE, and almost a light year in diameter. Comets we see from Earth don't always get absorbed after passing by us. I'm pretty sure planets traditionally form (relatively) where they now orbit because there were more planetesimals of certain densities (due to the distance from the star) that allowed acretion to happen. If everything was spread out evenly in a nebula, wouldn't each type of planet, respectively, (terrestrial and Jovian) be similar in size? Each planet should start gaining mass evenly. But then again I guess planet size is somewhat irrelevant when dealing with orbits. Its distance away and mass of the star that predominantly shapes the orbit of a planet. Maybe this is false, I'm not a physicist. But the asteroid belt consists of asteroids varied in masses which all orbit in similar location around the sun. In conclusion, I feel like migrations of planets outward occur VERY slowly and are somewhat rare. But as both of us have agreed, most debris ejected from the solar system occurred early on in its formation. Let's just be thankful Earth's orbit is stable!

13. Originally Posted by theorist
Originally Posted by SpeedFreek
The Earth isn't falling towards the Sun because the Earth is moving sideways in relation to the Sun. If the Sun (and the rest of the Solar System!) wasn't there, the Earth would move in a straight line. The gravity of the Sun bends that straight line into a line that curves around the Sun. So, the Earth is falling around the Sun, due to the gravity of the Sun.

Don't think of gravity as a force that pulls. Think of it as something that bends the straight lines that things fall along.

If you simply release an object above the Earth, it falls straight towards the Earth. If you give it a little sideways motion when you release it, it will fall in a curve towards the Earth. But if you throw it hard enough sideways in relation to the Earth, it will miss the Earth completely and fall around the Earth. That is what we call an orbit.
I have highlighted a quote from you, we are moving sideways relative to the sun because of the earths anti clockwise rotation? or ?
Or....

Angular momentum. The motions of a body are dictated by a combination of external gravitational influence and the initial motions of the stuff that formed the body.

Our solar system was formed from a swirling cloud of dust - the debris left over at the end of a previous stars life, and that star ended its life in a supernova event which sent matter outwards in a huge blast. So all this debris was already moving. Gravity took hold of this cloud of dust, and there would have been areas of that cloud with different densities. The more dense the area, the more the gravitational influence, so what you end up with is a cloud of dust swirling around, with clumps forming in it.

The region with the highest density (the largest clump) would have had the greatest gravitational influence, so most of the swirling dust would have started to collect there, but it didn't just fall straight in, it curved in because not all of the dust would have been initially moving in a straight line towards that place, there would have been a lot of different motions involved (the swirling!). This ultimately means you end up with a spinning clump of matter surrounded by dust. The spin is caused by the direction from which the majority of the incoming dust curved in from.

Once enough matter collected at the centre of this cloud a star was formed due to the pressure of the matter causing atomic fusion. The ignition of this spinning star would have blown all the dust around it away a bit, mixing the dust cloud up and causing more differences in the density of the cloud further out.

So, further out in this swirling cloud you have other smaller clumps of matter forming from the dust, due to gravity, and these clumps eventually became planets. These planets would be spinning and orbiting due to the sum of all the directions the dust came from that formed them and the gravitational influence of the clumps around them.

14. Originally Posted by SpeedFreek
The Earth isn't falling towards the Sun because the Earth is moving sideways in relation to the Sun.
Newton's cannon might help: Newton's Orbital Cannon

15. Originally Posted by Strange
Originally Posted by SpeedFreek
The Earth isn't falling towards the Sun because the Earth is moving sideways in relation to the Sun.
Newton's cannon might help: Newton's Orbital Cannon
Yes indeed, that is what I was trying to explain earlier:

Originally Posted by SpeedFreek
If you simply release an object above the Earth, it falls straight towards the Earth. If you give it a little sideways motion when you release it, it will fall in a curve towards the Earth. But if you throw it hard enough sideways in relation to the Earth, it will miss the Earth completely and fall around the Earth. That is what we call an orbit.

16. To the OP ; Why does the Earth not just fall into the sun ? ~ That Angular momentum, Orbital velocity,. Prohibit those collisions. Calculations of the mass and radial velocity are simple mathematics and are calculable and precise. A number of billions of years has settled the random errors away or into and mass and orbital velocities govern the stable Solar system we observe today.
Orbiting the Sun at such velocity as to balance centripetal force with gravitational distortion. A stable orbit is attained.

17. Originally Posted by SpeedFreek
Yes indeed, that is what I was trying to explain earlier
Yes, I just thought a picture might help explain it.

18. This is theorist after all, the more pictures (in bright coloured crayons for preference) the better...

19. So the big bang was only the beginning of our visual universe?

If so, how do we know that Earth was created by the Big bang and was not an already formed planet/meteor/ice planet,

that was drawn in by the suns gravity?

The stars are expanding outwards yet the Earth came inwards to what we see as our known visual center of the universe.
Why?

Planets, that orbit stars get blasted about the universe by super novas then attach to new stars?

Could Earth have once been attached to a different star, then blown across the galaxy , Iced over meteor that defrosted to give water?

20. Originally Posted by theorist
So the big bang was only the beginning of our visual universe?
What? Where did that come from?

But no, the big bang describes more than the observable universe. Probably the entire universe.

If so, how do we know that Earth was created by the Big bang and was not an already formed planet/meteor/ice planet,
The Earth wasn't created by the big bang.

The stars are expanding outwards
Stars are not expanding outwards (for any plausible interpretation of that sentence).

Planets, that orbit stars get blasted about the universe by super novas then attach to new stars?
Not as far as I know.

Could Earth have once been attached to a different star, then blown across the galaxy , Iced over meteor that defrosted to give water?
No.

21. Originally Posted by theorist
So the big bang was only the beginning of our visual universe?

If so, how do we know that Earth was created by the Big bang and was not an already formed planet/meteor/ice planet,

that was drawn in by the suns gravity?

The stars are expanding outwards yet the Earth came inwards to what we see as our known visual center of the universe.
Why?

Planets, that orbit stars get blasted about the universe by super novas then attach to new stars?

Could Earth have once been attached to a different star, then blown across the galaxy , Iced over meteor that defrosted to give water?
~ From this posting quoted; There is a awful lot of stuff you do not seem to grasp. I would dare suggest your understanding of the universe and this solar systems birth is in need of some study.. Nobody here is talking of the Big Bang.. The birth of the Universe. We are talking of a third generation star of the Milky Way Galaxy and how its Planets formed. Radial velocities and mass content drive the orbits of the solar system. 99% of the mass of this solar system is in the central star. The Sun. We and planet Earth are but a very small fraction of whats left. The Earth was never drawn into orbit the sun. It was formed from the solar planetary disk that the sun is the parent star of. As the planetary bodies cleared their orbits of debris and planets as we know them are formed. Not a single case is known of a planetary capture. If a planet is flung away from its star it is a wanderer.. and we have found some to prove this.
We are not at the center of the Universe. No center is found., as for your last two lines... NO. However asking questions is a good way to gain insight..

22. OK, so a super nova and the big bang are two different things ?,
a star collapsing affect is a super nova?,
there is two types of super nova?
a collapsed star leaves a white dwarf?

And thank you all for clearing up a few things.

23. Originally Posted by Strange
Originally Posted by theorist
So the big bang was only the beginning of our visual universe?
What? Where did that come from?
So the big bang produced inter stellar space as well and what ever is in inter stellar space?

24. Originally Posted by astromark
To the OP ; Why does the Earth not just fall into the sun ? ~ That Angular momentum, Orbital velocity,. Prohibit those collisions. Calculations of the mass and radial velocity are simple mathematics and are calculable and precise. A number of billions of years has settled the random errors away or into and mass and orbital velocities govern the stable Solar system we observe today.
Orbiting the Sun at such velocity as to balance centripetal force with gravitational distortion. A stable orbit is attained.
I get most of the basics of this topic, but i admit i m a bit lost when considering the statistical likelyhood of the planets of our solar system nicely forming stable orbit. It seems so unlikely, and as far as i know there is no planet collision planned in our system for billions of year until we approach suns death. Could you dumb this down some more?
Also our solar system form of a few planets around stars is quite common from what i ve read.

25. Originally Posted by Ximlab
I get most of the basics of this topic, but i admit i m a bit lost when considering the statistical likelyhood of the planets of our solar system nicely forming stable orbit. It seems so unlikely, and as far as i know there is no planet collision planned in our system for billions of year until we approach suns death. Could you dumb this down some more?
Also our solar system form of a few planets around stars is quite common from what i ve read.
It is unlikely, but all the planets that were going to collide have already collided, and the ones that are left are the ones that don't collide.

26. Earth has a velocity of orbit around the sun, what happens when the Earth gains weight from human population and space dust?

We slow down then get closer to the sun?

27. Originally Posted by theorist
OK, so a super nova and the big bang are two different things ?,
Yes. One was the "birth" of the universe. The other is the death of a star.

a star collapsing affect is a super nova?,
Yes. (roughly)

there is two types of super nova?
I think there are more than two. But maybe two general classes.

a collapsed star leaves a white dwarf?
Or a pulsar. Or a neutron star. Or a black hole. Or ...

It depends on the mass of the star, the type of nova and probably other things.

28. Originally Posted by theorist
Earth has a velocity of orbit around the sun, what happens when the Earth gains weight from human population and space dust?
The earth doesn't gain weight from the population because we are made of stuff (food) that was already here.

The earth gains several tons per day from dust falling onto the Earth. But also loses gas from the upper atmosphere. Overall the effect is insignificantly small and will have no effect on the orbit.

29. Originally Posted by Strange
Originally Posted by theorist
Earth has a velocity of orbit around the sun, what happens when the Earth gains weight from human population and space dust?
The earth doesn't gain weight from the population because we are made of stuff (food) that was already here.

The earth gains several tons per day from dust falling onto the Earth. But also loses gas from the upper atmosphere. Overall the effect is insignificantly small and will have no effect on the orbit.
Are the gases that we lose mostly helium and is this because it has to make way for the dust as two things cant occupy the same space?

30. Originally Posted by theorist
Are the gases that we lose mostly helium
Good guess. But it is actually mainly hydrogen (about 95,000 tonnes every year). Helium comes second (1,600 tonnes / year).
BBC News - Who, What, Why: Is the Earth getting lighter?

and is this because it has to make way for the dust as two things cant occupy the same space?
No. They are independent processes.

31. 'Theorist' Try and take in all that a very patent 'Strange' is telling you. listen and gain a understanding. This might require you seek information. Text book style. Learn what Solar wind is. What effect does gravity have on our upper atmosphere. Where does this in-falling dust come from ? It's what 'Wikipedia' can help you with. Do not jump to a conclusion when you do not have enough data.
The stellar born Solar wind tears at Earths atmosphere as the planet hurtles around the Sun. *We loose mass., but planet Earth also produces atmosphere. Venting volcanic gases and plants produce tons of new air daily. Balanced against the ever and constant rain of debris that falls into Earths gravity well. *We gain mass.
Now I am going to answer a question you will soon ask... Look out the window. What is your weather like today ? Could you say that it's not the same as yesterday.. yes. Lets call it climate change.. Everything over time does and will change. Even the amount of tax you pay and of what might kill you.. What I would like you to study is.. One part of the whole picture. You can not expect to take in all of everything all at once.. slow the input rate until you understand what it is you ask.. and I still applaud you for asking.

32. Originally Posted by astromark
'Theorist' Try and take in all that a very patent 'Strange' is telling you. listen and gain a understanding. This might require you seek information. Text book style. Learn what Solar wind is. What effect does gravity have on our upper atmosphere. Where does this in-falling dust come from ? It's what 'Wikipedia' can help you with. Do not jump to a conclusion when you do not have enough data.
The stellar born Solar wind tears at Earths atmosphere as the planet hurtles around the Sun. *We loose mass., but planet Earth also produces atmosphere. Venting volcanic gases and plants produce tons of new air daily. Balanced against the ever and constant rain of debris that falls into Earths gravity well. *We gain mass.
Now I am going to answer a question you will soon ask... Look out the window. What is your weather like today ? Could you say that it's not the same as yesterday.. yes. Lets call it climate change.. Everything over time does and will change. Even the amount of tax you pay and of what might kill you.. What I would like you to study is.. One part of the whole picture. You can not expect to take in all of everything all at once.. slow the input rate until you understand what it is you ask.. and I still applaud you for asking.
Thank you, I have a strange learning style, I find it hard to read lots of text information, not that i can not read, but have a limited attention span and tend to jump from one subject to another , then back again.

I do read the links provided as often they are short and to the point.

The link provided by Strange, from the BBC says that the Earth is indeed getting lighter, will the Earth speed up if lighter, or no matter what the size and weight of the Earth, the velocity will stay the same because there is no extra F involved ,
and according to Newton, the momentum will be at a continuous rate unless by obstruction?

33. And a wild guess, the Earth produces solar winds too, that consist mainly of hydrogen and not plasma?

34. Originally Posted by theorist
Thank you, I have a strange learning style, I find it hard to read lots of text information, not that i can not read, but have a limited attention span and tend to jump from one subject to another , then back again.
Maybe you should see your GP. This inability to concentrate might be treatable.

The link provided by Strange, from the BBC says that the Earth is indeed getting lighter
It says it is getting lighter by 0.000000000000001% per year. This is a change in mass of 1/100000000 of the mass of the Earth over its entire life. This will have no noticeable effect on anything.

35. Originally Posted by theorist
And a wild guess, the Earth produces solar winds too, that consist mainly of hydrogen and not plasma?
No. The clue is in the name solar wind.

I assume the gases that escape from our atmosphere will, mainly, be swept up with the solar wind. But that is not the same thing.

36. Originally Posted by Strange
Originally Posted by theorist
And a wild guess, the Earth produces solar winds too, that consist mainly of hydrogen and not plasma?
No. The clue is in the name solar wind.

I assume the gases that escape from our atmosphere will, mainly, be swept up with the solar wind. But that is not the same thing.
Did I understand Solar winds , correctly, from wiki, the sun basically gives off a vortex of a plasma stream/charged particles, that then expands from the sun outwards to a point where it has little affect/little notice?

37. http://en.wikipedia.org/wiki/File:Solar_Wind_and_Earth%27s_magnetic_field.png

I
f I was to hit a tennis ball at a fan in a vacuum, what would happen.

Would the ball stop and start to spin , trying to continue in a forward motion but unable because of the wind of the fan?

38. Originally Posted by theorist
If I was to hit a tennis ball at a fan in a vacuum, what would happen.
Would the ball stop and start to spin , trying to continue in a forward motion but unable because of the wind of the fan?
If it's in a vacuum there is no wind.

Thank you, I have a strange learning style
Yeah.
Not learning is not a "learning style", strange or otherwise.

39. Originally Posted by theorist
Did I understand Solar winds , correctly, from wiki, the sun basically gives off a vortex of a plasma stream/charged particles, that then expands from the sun outwards to a point where it has little affect/little notice?
I'm sure the dynamics are complicated and affected by magnetic fields all through the solar system, but yes there is a stream of charged particles out from the sun. Which is eventually stopped by the interstellar medium.

40. Originally Posted by theorist
If I was to hit a tennis ball at a fan in a vacuum, what would happen.
You would hit the fan. Depending on their relative weights, the ball would bounce off and the fan might move a bit.

41. Originally Posted by Strange
You would hit the fan.
Chuckle, now, now I know he's frustrating but comparing him to stuff that hits fans...

42. Originally Posted by Strange
Originally Posted by theorist
If I was to hit a tennis ball at a fan in a vacuum, what would happen.
You would hit the fan. Depending on their relative weights, the ball would bounce off and the fan might move a bit.
I understand a vacuum as no wind as such, like space, yet a solar wind is defined as a wind. Has the solar wind got any F with it, would it fly a kite for example?

43. Originally Posted by theorist
I understand a vacuum as no wind as such, like space, yet a solar wind is defined as a wind. Has the solar wind got any F with it, would it fly a kite for example?
It needs to be quite a big kite, but yes: Solar sail - Wikipedia, the free encyclopedia

44. Thank you strange for your help, so all stars produce solar winds?

If i could suspend myself central surrounded by fans set at the same velocity/output, that had enough F to move my body weight,
I would not move?

45. Originally Posted by theorist
Thank you strange for your help, so all stars produce solar winds?
Yes.

If i could suspend myself central surrounded by fans set at the same velocity/output, that had enough F to move my body weight,
I would not move?
Sorry, I don't know what that means.

46. Originally Posted by Strange
Originally Posted by theorist
Thank you strange for your help, so all stars produce solar winds?
Yes.

If i could suspend myself central surrounded by fans set at the same velocity/output, that had enough F to move my body weight,
I would not move?
Sorry, I don't know what that means.
I was considering and thinking about the pressure of solar winds against solar winds, knowing how we are surrounded by stars, and central to our visual universe, and thinking that one star would always be central, and the surrounding stars would expand outward with the F of the winds pushing against each other?

47. Originally Posted by theorist
I was considering and thinking about the pressure of solar winds against solar winds, knowing how we are surrounded by stars, and central to our visual universe, and thinking that one star would always be central, and the surrounding stars would expand outward with the F of the winds pushing against each other?
The solar wind stops long before that. Voyager has just reached the "heliopause" (the point where the solar wind is stopped buy the interstellar medium). But it is still within the solar system.

It will take tenss of thousands of years to leave the solar system, and even longer to get anywhere near another star.

48. Originally Posted by Strange
Originally Posted by theorist
I was considering and thinking about the pressure of solar winds against solar winds, knowing how we are surrounded by stars, and central to our visual universe, and thinking that one star would always be central, and the surrounding stars would expand outward with the F of the winds pushing against each other?
The solar wind stops long before that. Voyager has just reached the "heliopause" (the point where the solar wind is stopped buy the interstellar medium). But it is still within the solar system.

It will take tenss of thousands of years to leave the solar system, and even longer to get anywhere near another star.
The solar winds stop at the heliopause, or are they blocked as such, by the interstellar medium?

or do the winds just run out of steam as such at the heliopause?

added- just read an article on wiki and it says the heliopause is where interstellar winds meet the suns winds, so would not the winds push the winds as such?

49. Originally Posted by theorist
The solar winds stop at the heliopause, or are they blocked as such, by the interstellar medium?

or do the winds just run out of steam as such at the heliopause?
Yes.

It is like when you blow. You might be able to blow out a candle a few inches away, make one a foot away flicker. But you will have no effect on one a couple of feet away. The scales are larger for the solar wind because space is nearly a vacuum.

50. Are black holes caused by solar cross winds? causing pockets of space to twist?

51. Originally Posted by theorist
Are black holes caused by solar cross winds? causing pockets of space to twist?
No. Solar winds are incredibly weak and have little effect.

Black holes are caused by the enormous mass of a star collapsing when it has no more fuel.

52. Originally Posted by Strange
Originally Posted by theorist
Are black holes caused by solar cross winds? causing pockets of space to twist?
No. Solar winds are incredibly weak and have little effect.

Black holes are caused by the enormous mass of a star collapsing when it has no more fuel.
Ok, thank you strange for building a picture of solar winds and the universe for me. I now have a better understanding.

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