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| Topic: Moon was once much closer | |
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Actually.....
Some of the previous responds are incorrect. The Moon moving away from us will not fundamentally affect our orbit. The Earth's Orbital path is elliptical around the Sun while the Moon also travels elliptically around us. As it moves away the effect will be to reduce the difference between High and Low tides across the planet. When it was originally a lot closer 10-20 times closer; Tidal changes where far more dramatic; potentially in the region of 10s..100s of feet. So the likes of London, California etc would have been completely submerged every 24 hours :-) This is because the Moon pulls on the Water as a Mass and effectively drags it across the surface. The other effect is that over the Millenia the Moon has acted as a 'Brake' on the Earth's Spin. When it was much closer in it's earlier formation the Earth Day was actually around 20 hours. Over time the Moon's braking effect has resulted in us enjoying a 24hr day now. There will still be high and low tides when the Moon departs in a few Million years..... because as the Earth spins the Sun will also 'pull' on the Mass of the Sea. The biggest High and low tides result when the Moon is directly between the Earth and the Sun because the Moon and Sun are both then pulling on the same Mass of Water on the Earth's surface. |
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the sun will burn out and either a) go cold and we freeze or b) go supernova and blow us up before the moon drifts away...there's also a chance a large object could strike the moon sending it and us out of orbit before then...none of which are fun thoughts but all of which are millions-billions of years into the future presumably Factor in the large asteroids from space which keep missing Earth regularly. If one of those asteroids are large and hit us, we will be destroyed. That's one of the theories on how the dinosaurs went extinct. And I believe this to be fact. |
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I thought it was getting closer 
no, it's moving away about an inch a year... or about the same speed your fingernails grow.. |
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Very strange, but so interesting A guy called professor Brian Cox is good, and I used to watch the sky at night in the old days with the guy with the monical Patrick Moore, great old guy Sounds cool. I will have to check him out. try Brian Green as well, he explains a lot of physics in ways that people that don't know much about it can understand... |
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the moon holds us in our orbit around the sun once it drifts far enough away from us and breaks free we will drift out of the "Goldilocks zone" and earth will grow cold and life will cease to exist on this planet... sorry,this is not correct... the moon keeps the earth from spinning to fast, not much else... although, life might not have started on earth without it... http://www.scientificamerican.com/article/moon-life-tides/ |
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Just think for a second.
The Earth/Moon has an orbit with a barycenter. (wobble) The Earth/Moon/Sun has an orbital barycenter as well. (wobble) The Earth/Moon has a given mass gravitationally tugging on the Sun. It is a large mass with a smaller mass circling. If the smaller mass is reduced the larger mass's gravity will tug slightly less on the smaller mass at the same speed. So, if you remove the mass of the Moon, the Earth will slip to a larger diameter orbit of the Sun due to the smaller mass at speed. To remain in its present orbital position the Earth would need to slow down or regain the mass of the Earth/Moon. When the Moon exceeds the distance of the Earth's gravity affect on it, at that point, the barycenter has a larger wobble. When it breaks free, the moon will be shot in whichever direction the its mass is moving at the time the speed exceeds the gravitational anchor. The Earth will move slightly in the opposite direction. Spin a steel ball on a string above your head. Look at your hand, it wobbles. When the string's length gets longer the wobble gets more pronounced. Eventually the string will be longer than its strength to hold the mass of the ball and it will break. At the moment the string breaks the ball will fly off in that direction and your hand will move in the opposite direction. |
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Just think for a second. The Earth/Moon has an orbit with a barycenter. (wobble) The Earth/Moon/Sun has an orbital barycenter as well. (wobble) The Earth/Moon has a given mass gravitationally tugging on the Sun. It is a large mass with a smaller mass circling. If the smaller mass is reduced the larger mass's gravity will tug slightly less on the smaller mass at the same speed. So, if you remove the mass of the Moon, the Earth will slip to a larger diameter orbit of the Sun due to the smaller mass at speed. To remain in its present orbital position the Earth would need to slow down or regain the mass of the Earth/Moon. When the Moon exceeds the distance of the Earth's gravity affect on it, at that point, the barycenter has a larger wobble. When it breaks free, the moon will be shot in whichever direction the its mass is moving at the time the speed exceeds the gravitational anchor. The Earth will move slightly in the opposite direction. Spin a steel ball on a string above your head. Look at your hand, it wobbles. When the string's length gets longer the wobble gets more pronounced. Eventually the string will be longer than its strength to hold the mass of the ball and it will break. At the moment the string breaks the ball will fly off in that direction and your hand will move in the opposite direction. ..sems to make sense, but I've never read that it would |
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The Moon is the cause of the wobble. Just like planets are the cause of a star's wobble which is one way cosmologists detect stars with planets. A star wobbles and they look for occlusion.
The solar system formed by particles of matter coming together. The direction of rotation was determined by the mass offset during its formation. Stuff hit it lopsided and caused the mass to spin. The gravitational wave action was transferred throughout the solar gravitational influence. Uranus was struck by something in its past that caused it to rotate offset to the solar system's rotational direction. The planetoid that struck the primitive Earth was moving in the same directional rotation as everything else in the influence of the Sun. It had to be because if it had struck the Earth in the opposite direction it would have had to stop then start again to have the directional rotation it has now. Mass, distance and speed has much to do with any orbit. The Moon has been slowly moving away from the Earth because its mass to speed of orbit exceeds Earth's gravitational influence. Its too heavy and too fast for the Earth's gravity to stabilize it. If it were moving slower, at its current mass it would be falling closer to the Earth due to gravity exceeding the speed. If it were exactly the same mass as the Earth but orbiting at a different distance the barycenter would be somewhere in the middle of the space between the two masses. Like two equal steel balls spinning on a string, if there is a pivot and the strings never twist, the two balls will spin equal as long as there is stable rotational speed. Speed of rotation and mass is what determines the orbit. Venus is approximately 4/5ths of the mass of the Earth, it has a faster orbit than the Earth and it is closer to the Sun. The Moon's mass is about .012 that of the Earth. If the moon disappeared that difference in mass would change the distance from the Sun insignificantly but it would change it. But if the Moon were to be flung off into space, there would also be a directional movement at the Earth. That could add to the variation of its orbital mechanics. Directionally boosted forward at less mass would speed the mass causing it to widen the orbit. Directionally retarded backward would slow the mass speed and if it is equilateral - may not change the orbital mechanics. Then you have directly flung towards or away from the Sun and and tangent angle possible. |
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An earlier reply was very accurate. The moon over the time of its existence (made by a large bodied impact with the young earth that sent the earth's crust into space where forces formed it into the moon) has slowed the earth's spin - now at 1000 miles per hour. The earth's cycle was much shorter than 24 hours; shorter than 20. Much shorter. The moon also holds the earth much more stable in its wobbling axis - without it we would 'wobble' to an extent that life would be difficult to sustain. It does move further away every year and has been at about 1 1/2 inches per year. This is basically because even though it has slowed our spin, our gravity forces (because of that spin)- literally flings - it away. It will take a very, very long time before it leaves us significantly, maybe getting scooped up by Jupiter's gravitational field. It's questionable what will happen to the earth. However, the sun does have an expiration date: 2-4 billion years from now it will run out of fuel and become a white dwarf after first swelling and then collapsing in a spectacular event. Also, it's just possible that nearby Andromeda may collide with our galaxy first...so...perhaps the collision would change everything...
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An earlier reply was very accurate. The moon over the time of its existence (made by a large bodied impact with the young earth that sent the earth's crust into space where forces formed it into the moon) has slowed the earth's spin - now at 1000 miles per hour. The earth's cycle was much shorter than 24 hours; shorter than 20. Much shorter. The moon also holds the earth much more stable in its wobbling axis - without it we would 'wobble' to an extent that life would be difficult to sustain. It does move further away every year and has been at about 1 1/2 inches per year. This is basically because even though it has slowed our spin, our gravity forces (because of that spin)- literally flings - it away. It will take a very, very long time before it leaves us significantly, maybe getting scooped up by Jupiter's gravitational field. It's questionable what will happen to the earth. However, the sun does have an expiration date: 2-4 billion years from now it will run out of fuel and become a white dwarf after first swelling and then collapsing in a spectacular event. Also, it's just possible that nearby Andromeda may collide with our galaxy first...so...perhaps the collision would change everything... Thanx, there are some suppositions in your reply that are noteworthy for comment but on the whole I agree. It will take a very, very long time before it leaves us significantly, maybe getting scooped up by Jupiter's gravitational field.
Two things here. First is relative time. A long time for our relativity is not the same as a long time for the Earth or the Sun or the galaxy or the Universe. Relatively, the Moon will leave Earth's orbit in a short time considering the remaining life of our star and planet. The second, Jupiter's gravitational influence is part of the whole system's gravitational signature. Our Moon may not be captured by Jupiter's gravity before the Sun ends. There is a whole lot of space from here to there. Additionally, just like a ball being spun on a string, the angle of exit and the velocity of the Moon in that trajectory will determine the Moon's direction. It could be flung towards the Sun. It could be released behind Earths orbital path at an angle that misses the intersecting orbits of other planets to become locked into a cometary orbit. It could crash into Mars or Venus. It could get flung into the asteroid belt initiating asteroid trajectories that could intersect Earth at some point in the future. Andromeda may collide with our galaxy first...so...perhaps the collision would change everything...
Andromeda will merge with the Milky Way, not collide. Andromeda's Galactic black hole WILL collide with Sagittarius A (The Milky Way's galactic black hole) but it will do so only if the trajectories intersect. Most likely they will miss or glance one another and slowly orbit into each other. Here are two model simulations: http://youtu.be/4disyKG7XtU http://youtu.be/PrIk6dKcdoU Notice how the models show the galaxies acting fluid? Each star has a bow shock that acts like a barrier of outward push. For a collision to take place the trajectory will need to penetrate those bow shocks and heliospheres at just the right trajectory and with just the right velocity to impact the stars at their centers. Kinda like a needle penetrating a cell. The reason why we have a Moon is because it was not a direct impact with the Earth. It was a glancing impact. Here is some simulations of Moon formation. Note the fluid dynamics involved http://www.youtube.com/watch?v=Jf628Bugy_I http://www.youtube.com/watch?v=mQAdYWcA7ig http://www.youtube.com/watch?v=Fwl_JBQtH9o And a feature presentation Birth of the Moon from the show, Cosmic Journeys http://www.youtube.com/watch?v=WGTBJHFNywI |
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An earlier reply was very accurate. The moon over the time of its existence (made by a large bodied impact with the young earth that sent the earth's crust into space where forces formed it into the moon) has slowed the earth's spin - now at 1000 miles per hour. The earth's cycle was much shorter than 24 hours; shorter than 20. Much shorter. The moon also holds the earth much more stable in its wobbling axis - without it we would 'wobble' to an extent that life would be difficult to sustain. It does move further away every year and has been at about 1 1/2 inches per year. This is basically because even though it has slowed our spin, our gravity forces (because of that spin)- literally flings - it away. It will take a very, very long time before it leaves us significantly, maybe getting scooped up by Jupiter's gravitational field. It's questionable what will happen to the earth. However, the sun does have an expiration date: 2-4 billion years from now it will run out of fuel and become a white dwarf after first swelling and then collapsing in a spectacular event. Also, it's just possible that nearby Andromeda may collide with our galaxy first...so...perhaps the collision would change everything... nice reply, but 1 thing - the sun will grow to a red giant before it's a white dwarf, and will eat everything this side of Jupiter... possibly Jupiter too... |
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An earlier reply was very accurate. The moon over the time of its existence (made by a large bodied impact with the young earth that sent the earth's crust into space where forces formed it into the moon) has slowed the earth's spin - now at 1000 miles per hour. The earth's cycle was much shorter than 24 hours; shorter than 20. Much shorter. The moon also holds the earth much more stable in its wobbling axis - without it we would 'wobble' to an extent that life would be difficult to sustain. It does move further away every year and has been at about 1 1/2 inches per year. This is basically because even though it has slowed our spin, our gravity forces (because of that spin)- literally flings - it away. It will take a very, very long time before it leaves us significantly, maybe getting scooped up by Jupiter's gravitational field. It's questionable what will happen to the earth. However, the sun does have an expiration date: 2-4 billion years from now it will run out of fuel and become a white dwarf after first swelling and then collapsing in a spectacular event. Also, it's just possible that nearby Andromeda may collide with our galaxy first...so...perhaps the collision would change everything... nice reply, but 1 thing - the sun will grow to a red giant before it's a white dwarf, and will eat everything this side of Jupiter... possibly Jupiter too... True in part. During the red dwarf stage, the Sun's expansion could push the orbits of Earth and Mars outward. I have read scenarios for both reactions. That the Earth will be engulfed in the outer edges of the red dwarf and that the red dwarf will push the outer rocky planets to different orbits. Here is a version where the Sun engulfs Earth http://www.youtube.com/watch?v=iauIP8swfBY Here is one where Earth does not get engulfed by the Sun http://www.youtube.com/watch?v=wlHQV52fJ1A If you're real;ly interested, here is a video taken from Naked Science TV Show on the Death of the Sun http://www.youtube.com/watch?v=QuHr3ErT34I Here is an episode of The Universe TV Show on Dark Future of the Sun http://www.youtube.com/watch?v=4gqpaFBplHQ Our star, the Sun "real name Sol" is a 12 billion year star. It is currently around 4.5 billion years old. It is still growing and getting hotter but is in what is considered its Main Sequence. Sometime in the future, guess around 3-3.5 billion years, the Sun will begin to die. When that starts to happen it will expel gasses in phases. The star will begin to pulse its gasses off as the core compresses. Its not going to be fine then one day engulf or repulse the Earth. There may be a few tens of millions of years between pulses. The Earth will be long dead and uninhabitable long before the Sun does anything significant to our planet. In only 1 billion years, the increased Sun output will change the location of the life zone (Goldilocks Zone) for planetary orbit. Mars will be dipping into the zone. Mars has no magnetosphere to protect an atmosphere from solar wind so it might be warmer but will not have a livable atmosphere. |
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Hello
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There is a theory that the moon was actually part of Earth and a collision by another body caused part of the Earth to split throwing the moon into orbit.
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There is a theory that the moon was actually part of Earth and a collision by another body caused part of the Earth to split throwing the moon into orbit. i don't think they found a better theory yet... 
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For the Moon to be a captured body does not work because of its mass, speed of orbit and direction of deviance from orbit.
Plus, samples have been gathered from the Moon that show Earth properties that are missing from non-Earth gathered meterorites. |
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