A new "moon" is visiting earth for a while. It will go into orbit around the earth but won't impact it's surface. But if it will be under the influence of the earth's gravitational field then why wouldn't it fall to the surface? It is because that would be creating energy out of nothing and that is something that can never be done. This simple fact actually explains a lot.
A natural object, made of rock or metal, passing through space is called a "meteor". After it impacts a planet or moon it is called a "meteorite".
Meteors usually come from the Asteroid Belt. It is generally believed that the asteroids would have coalesced by gravity into a planet but the powerful gravity of Jupiter, the most massive of the planets, prevented them from coalescing.
A higher position or a higher orbit is a higher energy position. An object ten meters above the ground can be seen to have more potential energy than one five meters above the ground because, if both objects are dropped, the one that was higher will impact the ground with greater force. Likewise a higher orbit has more energy than a lower one. Gravity operates by the Inverse Square Law so that if we give an object in orbit three times the orbital energy it will orbit at nine times the original altitude, but with only one-third the speed.
What happens is that the orbit of Jupiter is further from the sun, and thus a higher-energy orbit, than the orbits of the asteroids. The mutual gravity between Jupiter and an asteroid gradually slows the asteroid, every time it passes Jupiter in it's orbit. This transfers orbital energy from the asteroid to Jupiter, causing the asteroid to fall into a lower orbit closer to the sun. Eventually the asteroid encounters the inner planets, and may collide with one of them or the moon.
Here is the mystery. We can see that there has been countless meteorite Impacts on the moon and on Mercury, as evidenced by the number of craters, but much fewer on the earth and on Mars. Part of the explanation is erosion that can erase evidence of meteorite impacts over time. There is weather on earth and wind and dust on now-dry Mars. But that cannot fully explain why there are so many more meteorite impacts on the moon and Mercury than there is on earth and Mars. There is another explanation that I have noticed.
Venus is also an inner planet but I am leaving it out of this explanation because it is shrouded in dense cloud and we cannot see it's surface.
Now here is what we must remember, and it is simple. It is that energy can never be created out of nothing.
When an object falls toward a planet it undergoes acceleration due to the planet's gravity. On earth the acceleration due to gravity of a falling object is 32 feet, or 9.8 meters, per second squared. For an object to fall into orbit around the earth it will have come from further away from the sun than the earth. When it is in orbit around the earth it is still also in orbit around the sun, since the earth itself is in orbit around the sun, the additional orbital energy from it's original higher orbit will go into it's orbit around the earth. The total orbital energy of the object will be that of it's orbit around the sun plus that of it's orbit around the earth.
But the fact that energy can never be created out of nothing determines whether the object will fall to earth as a meteorite or remain in orbit. If the object falls to earth it will be subject to the acceleration due to gravity of a falling object and will impact the ground with force. But there is no energy in gravity itself, it is just a force, and if the energy with which it would impact the earth exceeds it's original orbital energy around the sun, minus the orbital energy of the earth around the sun, then it would be creating energy out of nothing for it to impact the earth. Since this can never be done the object has to stay in orbit around the earth, rather than impacting the earth.
This means that, the more massive a planet is, the more likely that a passing object will fall into orbit around it, rather than impacting it, to avoid the impossibility of creating energy out of nothing. Also the closer a planet is to the sun the less it's orbital energy and thus the more likely that a passing object will have sufficiently more orbital energy so that impacting the planet, after undergoing it's acceleration due to gravity, would not be creating energy out of nothing. So the less massive a planet is, or the closer to the sun it is, the more likely it is to be impacted by meteors.
This explains why there are so many more meteorite impacts on the moon and Mercury than there are on earth and Mars.
Mars is not really a massive planet. But it is the furthest of the inner planets from the sun, thus having the highest orbital energy per mass. It is also the closest inner planet to the asteroid belt. This means that an asteroid that was descending to a lower orbit around the sun, due to lost orbital energy, would have the least orbital energy difference with Mars, compared to the other inner planets. Thus the asteroid would have less chance to not have to create energy out of nothing, which is impossible, if it impacted Mars after undergoing it's acceleration due to gravity.
This is why Mars does not have that many meteorite impacts and it's two small moons, Phobos and Deimos, are widely believed to have originated as asteroids that fell into orbit around the planet but have never impacted it, because to impact Mars would have required creating energy out of nothing.
Since the moon is in orbit around the earth it is the same average distance as the earth from the sun. But the moon is much less massive than the earth, it's surface gravity is only 1 / 6 that of the earth. This means that approaching meteors require much less additional energy than the orbital energy of the moon, per mass, to be able to impact the moon without creating energy out of nothing. This is why the moon gets struck by meteorites much more than the earth, at least per area.
Mercury is the planet that is closest to the sun, meaning that it has the least orbital energy of the planets. This is why it really gets hammered by meteorite impacts. It is also the smallest planet, if Pluto isn't included, although Mercury does have a high density because so much of it's interior is made of iron. Mercury was impacted with such force by one meteorite, the Caloris Impact, that the resulting shock wave affected the terrain on the diametrically opposite side of the planet.
WHY THERE ARE METEOR SHOWERS
There are regular meteor showers throughout the year. As the earth moves through it's orbit around the sun it passes through clouds of dust. Particles burning up by friction with the atmosphere is what produces the "shooting stars".
The dust was mostly left behind by comets. These comets are composed mostly of ice and collect dust in space as they move along in their orbits around the sun. The orbits of comets around the sun tend to be extremely eccentric, coming from far out in space and spending only a brief time near the sun before going far back out into space for long periods of time. There are comets with orbital periods of thousands of years.
When the comet gets close to the sun the outermost ice gets vaporized by the heat. This is what produces the visible "tail" of the comet, as the vapor reflects sunlight. It also leaves a trail of dust in space in the part of the comet's orbit that was close to the sun. It is this trail of dust that the earth passes through every year to create the predictable shower of "shooting stars".
The comets have orbits around the sun in geometric planes that are not the same at all as the earth's. This is why different meteor showers that occur every year seem to come at us from different directions in the sky. Each meteor shower has it's own direction.
Meteor showers, which occur on the same date every year as the earth passes through the cloud of dust during it's orbit around the sun, are thus named for the constellations in the sky that they seem to radiate from. Some of the meteor showers are the Perseids, Geminids, and, Leonids.
The first thing that is obvious is that the particles of dust cannot be in orbit around the sun. For the particles to enter the earth's atmosphere would mean that the particles are the same distance from the sun as earth. This would then mean that the earth and the particles would never run into each other since everything in the Solar System orbits the sun in the same direction, and objects at the same distance from the sun will orbit at the same rate. In a similar way Jupiter has two groups of asteroids that share it's orbit at Lagrangian Points L4 and L5, known as the Greeks and the Trojans, but which never meet Jupiter.
Neither is it possible that the particles of dust that are shed by the comet when it is near the sun continue with the momentum of the comet in the orbit of the comet. Comets have very eccentric orbits with long orbital periods. A comet comes close to the sun, where it's outer layers are vaporized into the familiar "tail" and it sheds the dust that it has collected in it's journey through space, for only a relatively brief time during it's long orbit. If the particles of dust continued with the momentum in the orbit of the comet they would be there for the earth to pass through them for one, or just maybe two, years. But the earth has been passing through the same cometary clouds of dust that have been producing the same predictable meteor showers that have been recorded for hundreds, or even thousands, of years.
The only possible conclusion is that the clouds of dust that the earth passes through during it's orbit around the sun are stationary in space and do not orbit the sun. I don't see how it could be any other way.
This requires some special explanation. These dust particles are made of matter, which has mass, and gravity acts on mass. So why aren't these clouds of dust that the earth passes through in it's orbit in orbit themselves around the sun? The vast clouds of dust and gas in our galaxy orbit the center of the galaxy along with all of the stars.
We know that the sun was preceded by a large star that exploded in a supernova. Some of the debris fell back together by it's mutual gravity to form the sun and planets. My theory is that at least one, but probably three, nova preceded the supernova. As stellar fusion proceeds to successively heavier atoms more energy is released per time and this upsets the equilibrium of the star. A nova is the blasting away of the outer layers of the star, in an effort to regain equilibrium. If that doesn't restore equilibrium then the star will explode from the center as a supernova.
We also know that the tremendous energy released by a supernova fuses together elements heavier than iron, which would not otherwise exist because the ordinary fusion process only goes as far as iron. This is why iron and lighter elements are exponentially more common than heavier elements, like silver, gold and, uranium. The much-lesser energy released by a nova fuses molecules together from the light atoms in the outer layers of the star. These light molecules include water, ammonia and, methane. Comets are composed mostly from these light molecules and the water on earth almost certainly came from comet impacts.
The comets were in orbit around the previous star before it exploded in the supernova. Some of the matter from the explosion collected back together by gravity to form the sun and the planets. But the sun was much less massive than the previous star had been. This means that the comets had much less orbital energy than before but the information of their orbits around the previous star could not just be lost. So the orbits of the comets around the sun "shrank" but with the high point, aphelion, remaining as it was before. This is why the orbits of comets are so elliptical.
In the first of the following diagrams the previous star is shown in red and the typical orbit of a comet around it in green. The second diagram is after the supernova and the falling back of a portion of the matter to form the sun and Solar System. But the sun, shown in black, has only a fraction of the mass of the previous star so the orbit of the comet, shown in blue, has to "shrink" to match the decreased orbital energy. These diagrams are not to scale.
The question is why the particles of dust don't orbit the sun so that the earth passes through them in it's orbit every year. The answer is that their orbits would necessarily contain orbital energy. The planets orbit the sun because they formed in the same way as the sun, from the supernova debris, but the comets existed, and were in orbit around the previous star, before the sun formed. For the particles of dust to begin orbits around the sun would thus mean creating energy out of nothing, and we know that this cannot be done.
The dust is not entirely stationary. It is stationary with regard to the sun but the sun itself is in orbit around the center of the galaxy, bringing the Solar System with it. The comets orbit the sun because they were in orbit around the previous star before it exploded.
So the reason there are meteor showers that repeat every year is that energy cannot be created out of nothing.
This also explains why the new "moon" that will be visiting us for a while will go into orbit around the earth, but will not impact the earth's surface. Because, if it fell to earth, it would be subject to the earth's acceleration due to gravity. This would give it more kinetic energy but that would be creating energy out of nothing, and creating energy out of nothing is something that simply cannot be done.
No comments:
Post a Comment