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If the Nighfall Asteroid was heading straight for Earth and then it suddenly, for no apparent reason, switched courses and headed in a different direction, would scientists have any theories (or at least theories that didn't involve a superstrong, superfast, able to hold his breath for 20 minutes, super man )

ML

The logical assumption would be some sort of outside gravitational source grabbed it or possibly something hit it - in which case they would start looking for evidence to prove their theories.

Theories:

Classic science:
- It couldn't have hit anything. Reason: The asteroid would be under 24/7 watch. If it where to hit anything with enough mass to change it's course, they would have seen it.
- Perhaps they got the angle wrong, and some other planets gravitational pull got in the way, and if they where to rationalize it long enough they would come up with a theory they could dish out to the public.

Really out there science:
- Dark Matter
- Black Hole

Non scientific:
- Divine Intervention
- Aliens

But a theory they could get behind at? No.

Oh, and does this mean we are going to get another MLT story somewhere in the not too distant future? Starts unpacking the material.

Michael

If we're postulating dark matter, super-string, or a black hole - that might not be detected until after it interacted with the asteroid - in which case they would start trying to trace its path backwards to see whatever else it interacted with.

But more likely, they would assume their measurements and/or simulations were wrong and the thing simply missed by a hair's breadth.

The nut cases of course would be invoking divine intervention and/or aliens.

Ahem.

Believing in Divine Intervention does not a nut job make... :rolleyes:

However, I would be giving God Almighty the praise regardless of the actual reason, because He is in control of all things.

My favorite quote. "Coincidence is God acting anonymously."

James

I wasn't referring to the quiet ones praying and helping, but the loud ones who would have been out on the sidewalks proclaiming 'repent now for the end is near' and then proclaiming their version of the deity was the one who stepped in.

Asking if someone believes in a deity implies there is a choice - rather ask which one they put their faith in.

Ahh, well, just wanted to be clear that those were the ones you meant

Just one of those days and I couldn't resist tweaking some noses out there...

Though, if there was an asteroid coming, I don't think many people would need nutjobs on the sidwalk to be reminded to repent. I think that activity would be pretty much a given for a LOT of people.

James

I took that response as grounds for changing the category for *divine intervention* to *non scientific*. (And just to prevent miss understandings: It was not "nut job" before.)

Michael

One possibility is the asteroid could be flying pretty darn straight towards Earth, but because it missed the gravitational keyhole, it wouldn't get sucked into an orbit and be able to finish the journey to impact. Instead it would miss Earth by a stone's throw of 20,000ish miles, and the people on Earth would be able to see an asteroid with the naked eye.

I say this because this is what's happening with the Apophis asteroid that's actually out there right now.

http://www.popularmechanics.com/science/air_space/4201569.html
just in case you want to read one of many stories. All the science mags, Popular Mechanics, Smithsonian, Sky and Telescope, etc say the same thing, that this gigantic asteroid hurtling towards us right now will most likely miss the keyhole in 2029 and it shouldn't be a problem. (Shame, I love catastrophe...)

Happy asteroid hunting,
JD

Thanks, guys. That's very helpful.

Funny how, in this case, the nutcases would be right, isn't it? After all, it was alien intervention.

Oh, and Michael, this does mean there is a new story being written. But then, I think 1999 was the last time I didn't have a story on the go

ML

Here's the thing...

An asteroid like that has a lot of inertia. It's really really massive, and odds are it's moving at literally astronomical speed.

Now, it can be hard to precisely calculate its velocity and its path. You can get reasonably good figures, but considering the vast distances involved, "reasonably good" only gets you so much. An asteroid can look like it's heading right for us but actually pass by well outside the orbit of the Moon.

That said... if there was a sudden and dramatic change, you'd be hard-pressed to explain it. Clearly, some gigantic force acted on it. But exactly what that force could have been...

The gravity of some large nearby object could shift its path, but that would happen very gradually. And you'd expect to see the object, or at least see its effects on other objects in the area.

A collision is possible. I'm not really sure if 24 hour monitoring is possible, given the rotation of the Earth. You'd tell everyone to look at it, but there are times when there'd be mostly ocean turned towards it, and times when sunlight (or lack thereof) might obscure it.

The thing is that if you know its old velocity, its new velocity, and its mass, you can figure out how much force must have been applied in order to make that change. A dramatic change would, as mentioned, require a very dramatic force. And you could also figure out the angle at which that force must have been applied.

So it's possible that a collision could do it. And it's possible that if the object struck the asteroid from behind, the impact would have been hidden. But you'd be able to figure out where it should have come from and how much momentum (mass * velocity) it should have had. An object small enough that it couldn't be seen through a good telescope would have to have been moving incredibly fast.

So...

If the change happened quickly, you'd probably suspect that it was a collision. You might hypothesize that it was a collision with the fabled "dark matter" (and a pretty big chunk of it, too). Or, depending on the calculated angle of impact, you might guess that it was another, smaller asteroid (too small to see at that distance). Possibly an unusually dense one, and almost certainly moving at very high speed. (Which would also help to explain why no one saw it coming.)

No, ML, I don't think that such a totally out-there event could be scientifically explained at all. Like Paul said, an asteroid that big carries a huge amount of inertia, and a sudden, abrupt change of direction just couldn't be explained scientifically. The gravitational influence of a planet couldn't do it, because, like Paul said, its influence would be gradual, not sudden. A collision with any sort of "normal" object is also out of the question. Or rather, a collision that powerful would probably shatter the asteroid altogether, turning it into a cloud of dust. Even if the asteroid didn't shatter, it would still release a lot of dust, which would be easily detectable by earth-based telescopes. A dust cloud is actually so much easier to spot from the Earth than the asteroid itself, because the scattered dust will reflect so much more sunlight.



This is Comet Holmes. It recently had an outburst, which caused it to become a million times brighter than before, and probably tens of thousands of images were taken of it in November and December last year. Yet the amount of dust that Comet Holes released was only about a fifth of the amount that was released by Mount Saint Helen during its famous outburst!



So an asteroid couldn't possibly collide with any sort of normal object without scientists being able to note the huge dust plume resulting from the collision.

So could it collide with an exotic object, like a black hole? No. The black hole's gravity would tear the asteroid apart, which, once again, would be very easy to spot from the Earth.

In 1994, Comet Shoemaker came too close to Jupiter and was torn apart. The Hubble Space Telescope took this image of "a string of pearls" of comet pieces:

Comet Shoemaker being torn apart by Jupiter

A black hole would tear apart an asteroid just like Jupiter tore apart Comet Shoemaker.

Anyway, if there was a black hole in our solar system, it would give its presence away by the strange way in which it would warp spacetime around itself. If there was a black hole in the vicinity of an asteroid, scientists would find themselves staring at the warped space around it when they followed the path of the asteroid. They couldn't possibly miss it!



Anyway, how likely is it that an asteroid will be hit by anything at all as it is sailing along in our solar system? Really, people, do you realize how much empty space there is between the individual objects in our solar system?

So frankly, ML, if you ask me... yes, I'd say that if an asteroid out there were to suddenly, inexplicably change course for no discernible reason at all, I'd say that there are really only three possible explanations:

1) ET intervened. He used his ultra-super-law-of-physics-defying anti-asteroid-spray to deflect it.

2) Superman intervened. He used his ultra-super-law-of-physics-defying strength to deflect it.

3) God intervened. He temporarily repealed the laws of physics which he has created himself and built the universe around, and then he deflected the asteroid.

If astronomers were to describe such an event in our own solar system, and if the huge majority of astronomers could come up with no scientific explanation for it (and I personally believe they wouldn't be able to), then I myself would be forced to believe in either ET, Superman, or God.

Ann

But if the impact occurred on the far side of the asteroid, couldn't the dust cloud be hidden by the asteroid's bulk/shadow?

Not to mention that the asteroid is made of rock, not ice (like a comet).

As for the likelihood of collision... I realize it's incredibly unlikely. But it is possible. You can't argue with results. If you see something suddenly make a noticeable course change, there has to be a reason for it. You wouldn't have predicted it would happen, but clearly, something did happen. If you don't know that Superman exists, and you have no other evidence of alien life, a collision seems to me like it'd be the best answer.

Most asteroids are believed to be quite porous, so that they would shatter easily.

If the collision happened from behind, then the object hitting the asteroid would shatter, if the asteroid didn't do so itself. (And really, even if the asteroid was absolutely remarkably sturdy, a collsion that was forceful enough to make the asteroid change course completely would certainly be able to cause a very, very noticable dust cloud.) Also, a collision would be noticable because the interloper would be flung in an opposite direction by the collision. I believe it was Isaac Newton who said: "For every action, there is an equal and opposite reaction."

Any natural explanation for such a totally weird event would be noticed and nailed down by astronomers. I'm certain of it. If there is no natural explanation, then I guess we are looking for a divine one.

Ann

Wouldn't visibility depend on how far out this was happening and how good the telescope(s) currently trained on the asteroid actually were? Nightfall was miles across, and was detected through an observatory telescope at considerable distance. Far enough that it was hard to make out any detail.

As for bounce-back... Either it shattered, and thus there's nothing to see but dust (which, again, could be obscured by the asteroid and its shadow), or it didn't. If it didn't... what about a completely inelastic collision? (i.e. It hit... and got stuck there.)

Also... what would/might they see in case of Superman? Might he show up as a blur in a telescopic picture? Would his actions cause a dust cloud?

Oh, and the other thing I mentioned before... Mightn't such an event be hailed as, quite possibly, the first direct evidence of "dark matter"? ... Though I suppose that would still involve a dust cloud from Nightfall if there was any actual impact.

The size of the asteroid (and its reflectivity, or brightness) would determine how far out it could be detected.

Any object that is so small that astronomers can't detect it at a distance where they can spot a few miles-sized asteroid is very tiny. The shadow such an object would cast is similarly small. Besides, the relative speeds of the two bodies - the asteroid and the interloper - would be high, so the two bodies would quickly move out of any shadow the other one may have cast.

Could Nightfall's own body shade its own dust cloud from our view? Not a chance. Could Comet Holmes shade its own dust cloud from our view? Of course not. Here on Earth, a dust cloud will soon "fall back on the Earth" again, because of the Earth's gravity. It will not leave the Earth, but will be contained by the atmosphere and then fall back again. But the self-gravity of a small body like Nightfall is negligible. It will not be able to hold on to its own dust cloud, but instead the dust that has been kicked up will just disperse into an ever more tenous cloud which grows in size until it disappears into space. There is no shadow that can hide such an event. I found a great image of how Comet Holmes' dust cloud grew in just a single day, but I wasn't able to post it because there is a parenthesis in the internet address to the site of the image. But trust me, such a dust cloud emanating from a small body would grow prodigiously and be impossible to hide.

Admittedly the dust cloud resulting from a collision could well be smaller - astronomers are certain that Comet Holmes didn't suffer from a collision but from an outburst of a "ice dirt" volcano - but it would still be large enough to be easily detectable. And the fact remains that large tenuous dust clouds are that much more easily detectable that small hard bodies like asteroids.

To me that is like asking if we could drop a bomb somewhere on the Earth and make it explode when it hit without causing a cloud of debris of some sort. Could the surface where the bomb hit remain undisturbed? Yes, it could remain more or less undisturbed, but only if the bomb didn't hit the ground at a great speed at all and only if the bomb didn't explode. In other words, if the surface is undisturbed, the bomb was a dud and not even much of a projectile. But a collision between two objects at the speeds we are talking about can only be compared with a huge bomb that does explode.

If the surface of an asteroid suffers an impact which is powerful enough to make the asteroid change its course, yet leaves the surface of the asteroid undisturbed, then I'd say we have just found proof that the Klingons are here. And Captain Kirk, too. That asteroid must really be a humongous space ship, and Captain Kirk just hit it with his phasers. The Klingon spaceship was sent wildly off course, but it remained more or less intact, because it had its shields down. But real asteroids don't have shields:



This is Saturn's small mooon Mimas. That huge crater to the upper right is the result of an ancient collision. When the collision happened, there was most certainly a gigantic dust cloud, too.

That depends on what the telescope can see of the asteroid itself, but I would say no. In order to see Superman, the telescope must be powerful enough to get an incredibly good look at the miles-wide asteroid. It must be able to see surface details only about a meter (three feet) across. But even then, the telescope would miss Superman if it didn't happen to focus on the particular spot of the asteroid where Superman happened to be
located.



This is an asteroid. If Superman had been there when the picture was taken, would he show up in this image? No. He would be too small in size, compared with the size of the asteroid.

In my opinion, Superman couldn't stop an asteroid by pushing against it. Most asteroids really aren't that sturdy. Their self-gravity is low. Many of them are like a collection of smaller pieces, relatively loosely stuck together. If Superman pushed hard enough at such a loose collection of rocky debris, I think he would plow right through the asteroid and shatter it. And there would certainly be a dust cloud.

On the other hand, if Superman somehow did manage to slow down the asteroid very gently, and then equally gently push it in another direction, so that the asteroid changed directions without breaking apart or developing significant cracks, then I don't see why there would be a dust cloud.

Personally I think not, Paul. And I think most astronomer would say that it wasn't possible. Astronomers invoke dark matter to explain why the outer parts of spiral galaxies rotate much faster than they should, according to Newton's theory of gravity. When astronomers observe the outer parts of spiral galaxies, they find that these outer parts seem to be rather sparsely populated, containing relatively little matter. Therefore, according to Newton's theory of gravity, they shouldn't rotate very fast. And yet they are seen to rotate almost as fast as the inner parts of a spiral galaxy. According to Newton's theory of gravity, this makes sense only if there are large undetected quantities of matter in or outside the outer parts of spiral galaxies. But since this "missing mass" can't be detected by any other means, it has been dubbed dark matter.

As far as I can understand, dark matter is supposed to have the same gravitational influence as ordinary matter, and ordinary matter couldn't cause an asteroid to make a sharp U (or L) turn. So dark matter shouldn't be able to either. Besides, several astronomers insist that dark matter doesn't really exist, and the real reason for the fast rotation of the thinly populated outer parts of spiral galaxies is that gravity acts differently in high-mass and low-mass environments. There is even a name for this theory, MOND, Modified Newtonian Gravity or something (but I don't remember where the D in MOND comes from). According to MOND dark matter isn't necessary to explain the rotation curves of galaxies, and therefore the reason for we can't detect, describe or explain the dark matter is because it doesn't exist.

Yet for all of that... we are trying to help ML come up with a possible scientific explanatin for why an asteroid would sharply change course, right? Well, in that case, I guess the dark matter theory may be the best explanation we can offer. Dark matter is supposed to be pretty much undetectable by ordinary means, so why not? And no one has a clue about what the stuff really is, if it exists in the first place. Who knows what a piece of it would do to an asteroid if they were to collide, or even if the asteroid ventured close enough to the little darkie to be affected by its sudden and unexpected gravity?

I think there are a number of scientific objections that could be made here, ML, but if you are looking for something that makes even the least bit scientific sense, dark matter might be the best explanation.

Ann

Of course you already have the asteroid moving in ways that an orbit can't fit. According to the script it was 2.7*10^4 meters across (17 miles). The Sun is 1.4*10^9 meters across and 1.5*10^11 meters distant. In order to be the same visual diameter so that it would cause a eclipse it has to be at the same ratio of diameter and distance. Which is 4500 kilometers if I've done it right. Which at orbital speeds means it would hit or be past us in about 10 minutes.

Anyway, thanks, everyone. That is very helpful. My guess, from reading the above, is that the scientist would try to explain it away (not wanting to admit that they had no idea), but that there wouldn't be much of a scientific explanation - leaving the field wide open for other interpretations.

ML

It would also be coming at Earth from inside Earth's orbit - unless the eclipse happened on its way toward the sun and it was going to hit after it made its way around the sun - an orbit that also doesn't work well.

Ain't astrophysics fun?

There's a difference between a scientific guess and a scientific explanation. The latter is only possible with enough evidence to support it.

In the case of this Nightfall asteroid on a trajectory to Earth ... Ann has brought up many clever points, truths and facts about it.

While there's nothing wrong in theory with black holes diverting objects from their paths, the attractive force of said black hole would need to be so large that it couldn't have gone undetected in our solar system. Today, scientists are for example studying invisible matter in the center of the milky way that causes whole galaxies to slingshot away from their expected orbits, thus proving the existence of a giant black hole. The natural force that needs to be present in our solar system would have been discovered (or not discovered but been expected) probably a century ago.

While physically a bit unrealistic it's entirely possible that something crashes into Nightfall our astronomers were previously not aware of. Take a look at this article for example - it talks about a watch system of potential threats to Earth and it's far from being complete even in today's time. Go back a few years before movies like Armageddon or Deep Impact aired and you will find a society that's even less aware of deadly impacts from "out there". When Nightfall can surprise the world such a short time before impact, a collision is at least a remote possibility.

Exactly. Plenty of theories to float (and knock down), but ultimately, you'd be grasping at straws. Clearly, something happened, but the possibilities are so incredibly unlikely that there'd be no clear backing for any of them.

(For the record, the "completely inelastic" comment was specifically in reference to the idea of bounce-back. I was treating the dust cloud as a separate issue.)