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Is Jupiter Earth's Cosmic Protector?
Hugh Pickens writes "Last Sunday, an object, probably a comet that nobody saw coming, plowed into Jupiter's colorful cloud tops, splashing up debris and leaving a black eye the size of the Pacific Ocean — the second time in 15 years that this had happened, after Comet Shoemaker-Levy 9 fell apart and its pieces crashed into Jupiter in 1994, leaving Earth-size marks that persisted up to a year. 'Better Jupiter than Earth,' say astronomers who think that part of what makes Earth such a nice place to live is that Jupiter acts as a gravitational shield, deflecting incoming space junk away from the inner solar system where it could do to humans what an asteroid apparently did for the dinosaurs 65 million years ago. 'If anything like that had hit the Earth it would have been curtains for us, so we can feel very happy that Jupiter is doing its vacuum-cleaner job and hoovering up all these large pieces before they come for us,' says Australian amateur astronomer Anthony Wesley, who first noticed the mark on Jupiter. But others say the warm and fuzzy image of the King of Planets as father-protector may not be entirely accurate. In 1770, Comet Lexell whizzed by the earth, missing us by a cosmic whisker after passing close to Jupiter. The comet made two passes around the Sun and in 1779 again passed very close to Jupiter, which then threw it back out of the solar system."
It's a bit like saying one speck of dust is protecting another speck of dust from other, smaller dust, as they swirl around an eddy of warm air in a coliseum.
Is Jupiter Earth's Cosmic Protector?
If this is true, it gives us another criteria to look for in distant solar systems that we suspect may harbor life or that we would like to colonize: a large shield planet in the same system capable of leaving the smaller world to develop uninterrupted.
It is interesting to wonder if our odds increase or decrease on being hit when there is a large massive body in our solar system. Like the article and summary say, some objects that would not have come close could be put on course for earth via Jupiter's gravitational forces. Who knows, maybe massive bodies like Jupiter pull more space debris into our system and make it more hostile than if it were just the earth orbiting the Sun?
My work here is dung.
Sorry for the dangling preposition in the subject, but regardless of whether or not Jupiter acts as a magnet for dangerous astral bodies, I wonder how risky it is to leave that job to Jupiter.
We have seatbelts in cars despite the mandatory brakes which are installed. We have random personal screenings at the airport even though we have a standardized process of metal detection and baggage scanning. We should not just sit idly without a comet/asteroid detection and elimination system just because Jupiter is catching the big ones for us.
We've been hit before. I don't want to get caught in the slamming door. How about some information, please!
... is the fact that eventually we have to get off earth and learn how to survive in the hostile universe anyway.
Now if Jupiter were like my boss, it would fling those comets at the earth with the message: "This issue is escalating rapidly. I need you to work on this today; send me status before you leave."
That Jupiter really sucks?
In astrology, Jupiter is considered the "greater benefic," the planet that bestows fortune, luck, and positive benefits.
Just sayin'.
The Earth will eventually be wiped out, obviously. We can't get lucky forever.
We'd better spread outselves out.
Is it actually more likely for a body to be directed away from Earth than to Earth by Jupiter? I mean, it seems that a body not destined for Earth could otherwise hit if affected by Jupiter's gravity sufficiently.
Jupiter is the only planet in our system close enough to the sun and with a deep enough gravity well for them to have a barycenter (common orbital center) outside the sun's surface. That sort of wobbly orbital mechanics has far more effect on trajectories of small bodies than a nice, neat set of concentric circular orbits. The sun-Jupiter system will be more likely to cause fluctuations that result in small interlopers to get thrown out of the system or sucked into one of their gravity wells. Seeing the result on Jupiter is rare. Seeing it at the sun is more common. Between the two they're going to suck up far more than hit elsewhere.
But their influence is only the majority of a chaotic multi-body system. Just because they account for the most hits doesn't mean they take them all and nothing gets through elsewhere. Of course some will miss the big guys and hit (or nearly so) some of the others. That's the nature of a chaotic system of orbital mechanics. They are not exerting influence in an intentional manner, rather a deterministic but fairly unpredictable manner.
To assume a certain thing always happens because it has happened, and also to say it not accurate because there is an exception, is the sort of low caliber absolutist thinking that's common in "modern" science reporting. I have no doubt the parties credited with these viewpoints understand quite well the situation, and the apparent controversy is a function of the author of TFA.
"I may be synthetic, but I'm not stupid." -- Bishop 341-B
the far side is much more cratered than the front side which shows how the Earth
...which is much larger than the moon, protects the moon from impacts more than the other way around.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
He just had a bad day.
After realizing what he did, he flicked that comet as far away from Earth as possible. And he said he was sorry.
The comet was never seen again. Lexell, after conducting further work in cooperation with Pierre-Simon Laplace, argued that a subsequent interaction with Jupiter had further perturbed its orbit, either placing it too far from the Earth to be seen or perhaps ejecting it from the Solar System altogether.
Mit der Dummheit kämpfen Götter selbst vergebens
Stop making sense!!!
We have to get our eggs off this speck of dust.
I find it amazing and worrisome that an object that size can get so close to Earth and hit Jupiter without astronomers learning about it until after the fact. To me, it is an indication that current near-earth object surveillance systems are not worth much.
Well, kind of, but look at it this way. If the Moon was a lone planet, it'd get craters everywhere equally. But it's not a lone planet, instead it has a bigger body always on the same side of it. Therefore, that there should be more impacts on the opposite side tells you that asteroids are quite attracted to Earth and that the Moon catches a lot of the when its on their way.
You just got troll'd!
Jonti Horner and BW Jones have written a series of papers on this, summarized in this Astronomy and Geophysics article The first paper deals with the Asteroids. The second, in press, considers the Centaurs The third, of perhaps most relevance to this discussion, considers the Oort Cloud objects.
(To simplify the simulations, Earth was inflated to one million times its actual size. A juicy target indeed)
The whole notion that some body that is on the other side of the sun from us half the time is protecting us doesn't really work in my mind. It seems that it only works if you imagine the universe is laid out on a line. Put the Sun at zero, the Earth at 3 and Jupiter at 10 and then anything heading your way from >11 has to get past Jupiter first. In reality we can't even rely on foreign objects coming in along the ecliptic.
We don't do that because the likelihood of somebody abusing the weapons to kill us is substantially higher than the risk of being killed by an impact. Further more you're assuming that we'd get it right, and let's face it we tend to be kind of hit or miss on things like that. We were able to more or less successfully fight the ozone layer problem, but pretty much completely refuse to do anything about global climate change.
I'm not sure what makes you so sure that there'll be much left by the time a space object becomes a risk or that we'll be able to spot it in the first place. Many of those meteors move pretty damn fast.
There's actually no "Present Participle" for making/molding/pressing dies. The action itself is usually "pressing", "blanking", or "broaching". More information here.
On a side note, the Bengal tiger is quite intelligent and resourceful. I wouldn't be surprised if they did decide to go into the manufacturing business.
Entomologically speaking, the spider is not a bug, it's a feature.
Wrong. Both sides of the moon have had the same level of impact, and the 'far' side is not facing the asteroids any more than the 'near' side. The earth-moon system rotates in space and the moon rotates around the earth so both faces are in the direction of the asteroids all the time.
The 'near' side of the moon only looks smoother because mare lava flows have smoothed it out somewhat. It's just chance that put those flows on the side we see.
Fun fact: if the earth had no weather, it would look just like the moon in terms of impact craters. The earth is much bigger and has actually been hit more often. But our weather has eroded most of them.
Sig for hire.
> The Earth has not yet faced a galaxy coming straight at it.
The Earth is facing a galaxy coming straight at it. The Andromeda Galaxy is on a collision course with the Milky Way, and there is a very real possibility that the Sun will be ejected from our Galaxy when this happens. Fortunately, this is not going to happen for about three billion years
Just because you are paranoid does not mean that no-one is out to get you.
The absolute worst possible outcome is that we have made so many other species extinct by that time that there is no stable ecological niche for humans and we go extinct too. I'm not arguing that this is particularly likely, but it's definitely worse than your worst case, unless you were counting subsistence 'living' with population = 0. However, adding that to your list of consequences with a small probability (0.5% or so) shouldn't make any difference to you. In fact, adding it with a very large probability (99,99995% or so), given your 'logic', doesn't make any difference either, so carry on.
Just as a hint, real logic means, if you introduce different facts, you just might reason to a different result. Your real, if unstated 'logic' is 'If it's not me it hurts, it's not a tragedy'. Since you didn't state it openly, but a bunch of unconnected claims you call logic, you don't have to be concerned that someone would point out that you are a sociopath, using an entirely emotional argument to provide pseudo-justification for being a rat-bastard who has basically told every single person reading this you don't care if their loved ones and descendants live or die.
Who is John Cabal?
Wrong. Both sides of the moon have had the same level of impact
Wrong, the far side has about 1.67 times more recent impacts than the near side (citation).
The 'near' side of the moon only looks smoother because mare lava flows have smoothed it out somewhat. It's just chance that put those flows on the side we see.
No, we don't know that, there surely is a reason other than chance, we just don't know for sure what it is yet. Also, not all of it was covered by lava flows, and you can tell these areas look different from the far side. Well at least they look different to me.
Fun fact: if the earth had no weather, it would look just like the moon in terms of impact craters.
I'll assume that you chose the word weather instead of atmosphere for a reason, not too sure why, but the Earth is geologically active and has an atmosphere (assuming you weren't talking about there not being an atmosphere) then it would look more like Venus. And Venus doesn't have so many visible craters. Yeah, there's quite a difference between a body that died over 3 billion years ago and one that's still active, radiating and erupting.
You just got troll'd!
In retrospect, "The tiger is cast" would have been cooler for Caesar to say before crossing the Rubicon...
Whew! That's a relief... I thought you said three million years.
"Slow down, Cowboy! It has been 3 years, 7 months and 26 days since you last successfully posted a comment."
Yes, but have you ever tried to cast a tiger? Not only is picking it up awkward, but they don't really want to let go and become a flying creature. On the other hand, once the task is done you're likely to think a battle will be a relaxing activity.
Actually from what I understand, getting ejected from the galaxy would probably be the best outcome.
There is also a chance of the Sun being put into an orbit that takes it through uninhabitable parts of the galaxy such as the core. Also when the collision happens it will trigger a very large spurt of star formation leading to more supernova and just large amounts of radiation from large new stars. Not to mention the chance of a close encounter with another star disrupting the orbits of the planets in the solar system.
https://en.wikipedia.org/wiki/Inverted_totalitarianism
Nonsense. If you want to cast a tiger, you put an ad in Variety.
if they don't hit something they most likely won't hit anything.
An astutely profound observation. Absolutely profound.
HSJ$$*&#^!#+++ATH0
NO CARRIER
Oooh, can't wait for that to happen!
This part of the neighborhood is getting boring.
The point is that not only does Jupiter protect the terrestrial planets now, but that Jupiter has protected Earth from the birth of the solar system. This is one reason that Earth isn't yet another gas giant.
The recent controversial redefinition of the word "planet" (http://en.wikipedia.org/wiki/IAU_definition_of_planet) discusses this "vacuum cleaner" effect as the third of three criteria:
Jupiter is by far the largest planet and has by far the largest such effect. A lot of the reasoning in the comments has caused one to question how well Astro 100 courses are being taught, but perhaps it is ok to venture one simple statement for why Jupiter preferentially protects the inner solar system. The comets that threaten us originate in the distant Oort Cloud (http://en.wikipedia.org/wiki/Oort_cloud). They visit the inner solar system, but their orbits all begin far outside. It is thought that external perturbations play a role in causing them to plunge inwards. Jupiter (to oversimplify outrageously) stands between us and the bombardment.
Fundamentally this is the famous "three body problem". The equations describing Newtonian gravity are straightforward to solve for two bodies, and impossible to solve precisely for three or more. Relativistic corrections add a bit of spice. As a result planetary mechanics requires numerical integration.
The solar system is full of neat resonances and points of stability such as the Lagrangian points. Jupiter's Trojan asteroids (http://en.wikipedia.org/wiki/Trojan_(astronomy)) cluster at L4 and L5 and are thought to be as numerous as those in the main belt. Our Moon's tidal locking is a) imperfect (since the orbit is rapidly growing (http://en.wikipedia.org/wiki/Moon#Orbit_and_relationship_to_Earth), and b) simple compared to resonances (http://en.wikipedia.org/wiki/Orbital_resonance) between other bodies.
That's right. You can't.
-- I have a private email server in my basement.
Last Sunday, an object, probably a comet that nobody saw coming, plowed into Jupiter
First, I'd like to apologize for being slightly off-topic.
I wonder why pretty much all astronomy sources are unwilling to state with certainty that Jupiter has a rocky core. It's only natural that more solid material has fallen into the atmosphere than has been captured in orbit. It's not like the comets and meteorites will 'orbit' for very long within friction of the atmosphere, so the only place for solid matter to go is the center.
Low odds of an intercept. Now multiply that by thousands of orbits the body will make. The important factor is not that Jupiter will immediately intercept every body; just that a typical body will be more vastly more likely to be intercepted first by Jupiter than the Earth.
Isn't about three billion years when the sun is supposed to be in it's bloated red giant phase anyhow, making whether the solar system is ejected or whether we end up in some inhospitable part of the galaxy a rather moot point?
Looking at it, seems like either outcome means lights out (well, probably more like lights on one hundred million times more powerful) but whatever happens, here is where we don't want to be.
Moved to http://soylentnews.org/. You are invited to join us too!
(Pyongyang, NK) A defiant North Korea announced the launch of a projectile the size of several soccer fields (football fields in the U.S.) that struck Jupiter today. As it descended into Jupiter's cloud tops it was transmitting data and broadcasting the "Song of General Kim Il-sung" and "Song of General Kim Jong-Il", about Kim Jong-Il and his father.
North Korea's neighbors condemned the launch as "unfortunate". The U.S. State Department declined to comment, although in another display of his ability to mitigate, President Obama has invited Kim Jong-Il to meet him on Jupiter for a beer.