Posted on 09/14/2009 11:06:56 AM PDT by SunkenCiv
Jupiter already has an abundance of moons, but from 1949 to 1961 it had another, temporary satellite in the form of a comet trapped in the gas giant's gravitational grip. Comet 147P/Kushida-Muramatsu was captured as a temporary moon of Jupiter in the mid-20th century and remained trapped in an irregular orbit for about twelve years, astronomers announced today. There are only a handful of known comets where this phenomenon of temporary satellite capture has occurred and the capture duration in the case of Kushida-Muramatsu is the third longest... The team used recent observations tracking the comet over nine years to calculate hundreds of possible orbital paths for it over the previous century. In all scenarios, Kushida-Muramatsu completed two full revolutions of Jupiter, making it only the fifth captured orbiter to be identified... Asteroids and comets can sometimes be distorted or fragmented by tidal effects induced by the gravitational field of a capturing planet, or may even impact with the planet. The most famous victim of both these effects was comet D/1993 F2 (Shoemaker-Levy 9), which was torn apart on passing close to Jupiter and whose fragments then collided with that planet in 1994. Previous computational studies have shown that Shoemaker-Levy 9 may well have been a quasi-Hilda comet before its capture by Jupiter... The team has also confirmed a future moon of Jupiter. Comet 111P/Helin-Roman-Crockett, which has already orbited Jupiter three times between 1967 and 1985, is due to complete six laps of the giant planet between 2068 and 2086.
(Excerpt) Read more at space.com ...
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There's a lesson in there for all of us. I can see entire new philosphies of business managment being spawned by this.
The more we learn, the more we know what we don’t know.
I don’t get it. How can a body be captured by gravity make a few orbits then spin off again? Seems like once you are in gravity’s grip there would be no letting go......? Either orbit forever (moon), crash into the planet, or a near miss anf off you go again.
“The more we learn, the more we know what we don’t know.”
I completely agree. I find the fact that I don’t have all the answers quite liberating.
Think of it like playing pool in 3D
It has been noted that Jupiter sweeps up a lot of these bodies that might otherwise collide with Earth.
Without Jupiter, the development of advanced life on Earth may not have been possible.
God thought of everything.
If it were a simple two body problem, you would be correct, except that the two body problem doesn't allow any mechanism for capture in the first place.
The comet was originally in orbit around the sun. Depending on how it approached Jupiter, he may have imparted more velocity and flung it out of the solar system or in this case, the gravitional drag of Jupiter slowed it down just enough that it no longer had escape velocity from Jupiter and was "captured".
If the comet was moving away from Jupiter as it approached his orbit, Jupiter would have slowed him down. The angular momentum of the Jupiter-Comet system is in variant in a coordinate system centered on the sun. Jupiter just took a little of the comets angular momentum and sped up very slightly, while the comet was slowed down.
The resulting orbit will be perturbed by the influence of the sun, Jupiter's moons and other gas giants and may eventually acquire enough velocity, relative to Jupiter, to escape Jupiter (for now) and continue on his way, either out to the Oort Cloud or back towards the sun.
Since the comet's resulting orbit crosses Jupiter's, it will have other encounters with Jupiter until it eventually is flung from the solar system or collides with him or an encounter with another body deflects his orbit away from Jupiter's.
If you want to see really weird orbital mechanics, read up on horseshoe orbits.
Some say gravity isn’t the only force in effect on celestial bodies. Electromagnetic factors may be in play. This is based on plasma cosmology.
If you’re interested, here is a movie on the subject:
http://video.google.com/videoplay?docid=4773590301316220374&ei=-jEwSpveL4nKqgK5osCtDw&q=thunderbolts+of+the+gods&hl=en
Can’t argue with that. :’)
Picture of the orbit.More Moons Around Earth? It’s Not So LoonyEarth has a second moon, of sorts, and could have many others. Cruithne, the 3-mile-wide (5-km) satellite, takes 770 years to complete a horseshoe-shaped orbit around Earth, and will remain in a suspended state around Earth for at least 5,000 years. Every 385 years, it comes to its closest point to Earth, some 9.3 million miles (15 million kilometers) away. Its next close approach to Earth comes in 2285. "We found new dynamical channels through which free asteroids become temporarily moons of Earth and stay there from a few thousand years to several tens of thousands of years," said Fathi Namouni, one of the researchers, now at Princeton University. Namouni’s colleague Apostolos Christou said, "At specific points in its orbit, it reverses its rate of motion with respect to Earth so it will appear to go back and forth." In his view, there are three classes of moons – large moons in near-circular orbits around a planet, having formed soon after the planet; smaller fragments that are the products of collisions; and outer, irregular moons in odd orbits, or captured asteroids like Cruithne. In the past year, astronomers have reported finding such objects around Uranus.
by Robin Lloyd
October 29 1999
It can happen. You should not look at the planet and the comet in isolation- there are other gravitational forces at play, too- for example, that of nearby moons, planets and the entire solar system.
Occasionally, the orbital positions may create a situation where the forces from those external fields, or from orbital eccentricity, may allow for the captured body to escape.
Slapping my forehead! Seems obvious now. I guess I was preplexed at the capture and release aspect, thinking too simply to realize that obviously near-by bodies would also be interacting too.
Thanks all.
Indeed. I heard that, too. Jupiter is our big cosmic buddy.
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