Hello, new here..
This is coming from out of left field, but I've gotta ask before I make an unrealistic blunder in something I'm writing.
Is there any way possible that some sort of catastrophic event - say, an asteroid hitting the Earth or something happening to the sun, or even something else - that would force the Earth closer to the sun and permanently change its orbit?
I'm not talking closer-to-the-sun as in boiling oceans, life dying, etc, but more in a way of coming closer that would alter the climate of the planet enough to say, make it hotter and more unpleasant.
I'm writing a scenario where all of the world's glaciers would melt, and I'm exploring this as a potential avenue for that to happen.
If it's completely not possible, no ifs, ands, or buts, let me know too. Thanks

Welcome to BAUT.

It takes a lot of energy to change the Earth's orbit. Changing the orbit by an impact would impart so much energy that, at best, the Earth would be a molten blob.

Now, if you want to change the orbit over millions of years, and you have advanced technology, you might use a dwarf planet making close (but not destructive) passes.

Well, some think global warming could do that eventually. If you want to make it certain, you might have an eruption of a super-volcano to add a lot more CO2. Of course, a super volcano would have other effects . . . .

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I think an easier way to make the scenario come about would be to heat up the sun rather than get the earth closer. All you have to do is say the scientists didn't understand something about solar dynamics, and suddenly the sun starts heating up.

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The only plausible way that I can imagine to significantly alter Earth's orbit
in the next 100 years or less would be an encounter with a stellar-mass
black hole. Any body heading toward Earth large enough to affect Earth's
orbit other than a black hole would be visible more than a hundred years
before it arrived, if it was moving at a reasonable speed. A fast-moving
stellar-mass black hole with absolutely no accretion disk might be able to
sneak up on us from either the north or the south without disturbing the
orbits of planets and asteroids too long in advance.

If the black hole was less than stellar mass -- say, about the same mass
as Jupiter, or Earth, or even Mercury -- it would be able to get closer
before being detected. Such low-mass black holes are not expected to
exist, because there is no way known for them to form. All black holes
should be about twice the mass of the Sun or more.

The encounter would have to be at a great enough distance to not pull
Earth apart and suck off Earth's atmosphere. A stellar-mass black hole
passing at a distance of half an astronomical unit should easily change
Earth's orbit significantly without doing much more direct damage than
causing some very high tides. A Mercury-mass black hole might need
to pass at about the distance of the Moon, which means you have two
really strange things going on: A black hole of a completely unpredicted
mass, and it happens to be headed almost straight at Earth, just missing
us by a whisker. Such a coincidence would be implausible to me.

-- Jeff, in Minneapolis

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http://www.FreeMars.org/jeff/

"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves

Something as plausible and also interesting might be a large rogue planet zooming near the Earth/Moon system and causing our axis to tilt much more toward the Sun, which should do the melting trick. [Of course, the opposite hemisphere will experience much colder temperatures, then, 6 months later, the sides are reversed.]

It is believed that a handful of planet-sized objects get ejected during the early formation period of most star systems. Also, planet-sized objects are invisible to telescopes until they are inside the Oort Cloud region. For instance, even Jupiter would have an apparent magnitude of about 31 (Hubble Space Telescope's limit) at 10,000 AU.

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BTW, if you are choosing an avatar for your sunflowerqueen name, please consider a white sunflower. [Our Sun (as seen in space) is actually a white star and without a smidgen of yellow.]

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I would say that the most possible event (however improbable it might be) would be an encounter with another planetary body, say a rogue coming in, passing Earth in such a way as to gain some velocity, and then exiting stage left, never to return.

That would make Earth's orbit more elliptical, with a perihelion nearer to the sun and an aphelion at the current orbit. Tilting the Earth's rotational axis is unlikely, I think. See A World Out of Time by Larry Niven.

Sort of a one-time Planet X (X a la Nancy Lieder).

Fred

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All of this might well be true.... BUT. Please remember we are talking of a work of fiction. Where the most improbable often happens. I mention this because with astonishing regularity a fringe group of completely insane people come roaring into these pages with stories and questions regarding the impending doomsday event that might just be this OP. Largely miss-understood.
I like the idea of just upsetting the Axis tilt angle. It sounds easy... six month days and nights...

The more improbable things that happen in a story, the more it bugs me. Please, posit one unlikely/impossible "thing" at a time and don't ignore its consequences.

I believe (with no math to back it up) that altering an orbit slightly can be done far more easily, and with less disruption, than tilting a spin axis.

Fred

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"For shame, gentlemen, pack your evidence a little better against another time."
-- John Dryden, "The Vindication of The Duke of Guise" 1684

Yes, the more believable, the more interesting (unless its been done before).

Why not both? Any rogue planet that would cause an axis tilt would also change the orbital path.

I suspect the axis could be altered if the planet came near the Moon but above or below its orbital plane. How long it would take to cause Earth's tilt to change would be a good question, but it would, I think. In this scenario, there would be some strong tides as the planet swung by, but tides would get strong later assuming the Moon would have a much closer perigee.

I'm kinda guessing here. Can such an event, or other, not tilt the Earth's axis?

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Understanding the force required to change the angle of orbit or place forces on Earth to significantly altar the distance from the sun... Can not be done without understanding the mathematics of it all. As an example of this; 'What if' a small black hole were to pass through this solar system, say at ten or so AU. Having not actually hit anything how much disruption would be the result.?... Possibly much.
The fine balance of this solar system are not so easy to disrupt. Some considerable mass object would be required.

Oh yeah, I remember now. This is your pet peeve George.

Hi Jeff,
I agree somewhat with what you say but in my own experiments in simulating rogue solar masses, I find that a close pass with an object nearly equal or greater than the sun actually pulls the sun out of whatever course it is on and sends the entire solar system careening. A Jupiter mass object which passes close to the sun will perturb the inner solar system and may even cause the earth to shift (slightly) to a closer or at least more elliptical orbit.

Now mind you, my results are based on simulation and a far from perfect simulation at that.

One thing is clear, an impactor striking the earth and changing its orbit would be absurd as no life-form on earth would likely survive to worry about how hot its getting.

Altering the Earth's orbit can be done without extreme tidal forces, by a sufficiently large object a sufficient distance away. Also, remember that there's another important body involved in Earth's orbit...a brown dwarf making a sun-grazing pass through the system might give enough of a tug on the sun to noticeably affect Earth's orbit and climate (and those of every other body in the solar system), and with the potential for violent tidal effects on the sun and intruding star to add to the mix.

Applying enough of a torque via tidal forces to alter its rotational axis requires something rather closer...and I doubt Earth would be recognizable afterward. There wouldn't be anyone left to be inconvenienced by the extreme seasons.

Another option to consider...a chance encounter between a much smaller object and Mercury, leading to a dust and rubble disc between Venus and the sun. Such a disc would probably not be in Earth's orbital plane, and would dim sunlight when Earth was near the plane, cutting a dark stripe across the sun, and brighten it when Earth is further out of the disc plane, reflecting extra sunlight toward Earth. Two little winters and little summers per year. Probably more of the latter than of the former...it'd probably be a pretty sparse ring, and more of it would be reflecting than would be blocking. Short lived, but they'd probably last long enough to cause problems. Or closer to home...a collision with the moon that gives Earth a set of temporary rings.

It may do that, but two (rather opposite) things:

1) Any motion of the Solar System as a whole you can just ignore.
It may go off the screen (in some simulators) but that isn't a problem
with the real Solar System.

2) Anything that moves the Solar System as a whole as a result of
passing near the Earth (say, at a distance of 1/2 AU) is also going
to change Earth's orbit around the Sun pretty significantly.

Oh -- and did your simulations have the alien body pass through the
Solar System at a high inclination to the ecliptic? Or were you doing
2-D simulations, which is all I've ever done?

I'm imagining a 2-solar-mass black hole passing a bit less than 1 AU
from the Sun and 1/2 AU from Earth, at 60 degrees to the ecliptic.

-- Jeff, in Minneapolis

__________________
http://www.FreeMars.org/jeff/

"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves

The simulation is 3D but in the thumbnails I am plotting the x-y plane. Just to quickly demonstrate -

Image 1 shows the inner solar system out to the oribit of Jupiter. All planets including pluto (I know technically not a planet) are calculated and in addition, the five largest asteroids which are plotted between Mars and Jupiter.

In image 2, a 0.01 solar mass perturber passes from the bottom to the top on the right between the asteroids and jupiter. The solar system is pulled off center, but all of the orbits visible, remain fairly stable.

In image 3, a 0.1 solar mass approached on the same path. Long before it crosses, Jupiter's orbit, the solar system is pulled toward it.

In image 4 the 0.1 solar mass object has passed and the solar system is in chaos. Jupiter is flying off to the left and the rest of the planets are struggling to remain in orbit. Remarkably, Mercury looks undisturbed.

Notes: the simulation is running 43200 second timestep so some error is definitely present. The integration is an 8th order sympletic.

btw - this is fairly flat inclination to the ecliptic.

Attached Images

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	orb2a.JPG (40.9 KB, 10 views)
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First off, thanks for all the replies.

My original idea was to have an extreme, unexplained version of global warming happen to make the glacier melt within 1000-2000 years.. But that seemed kind of too convenient, and I try not to do that. The super-volcano idea is interesting.. I'm a bit of a science-newb but I remember hearing something about there being a huge super-volcano under Yellowstone park.. Would the resulting ash winter be the "other effects" you mean?

I'm crazy, but not that type of crazy. I have no ulterior motives here.

I quite agree. It's why I'm posting here instead of running with some half-baked thing I made up.

I'm reading through the rest of the replies.. This all looks promising.

"Would be visible" doesn't mean that it would be seen. New objects that were theoretically visible decades or even longer ago are regularly discovered. If a cool brown dwarf were headed directly our way wouldn't it just be another low proper motion dim star? How far away could we see an Earth mass object?

Well there are the theoretical primordial black holes that haven't been detected yet.

As to the idea that encounters with passing planets would radically alter the Earth's obliquity: that makes no sense to me at all. Actually I can think of a mechanism. If the visitor took out the moon, then Earth's obliquity would be destablized over periods of the order of 100k years.

A near-by brown dwarf would like glow like a spot-light on one of our infrared surveys. In that way I think it would be visible and its proper motion measured quite easily and early. In general, brown dwarfs are much more massive than the earth, five hundred times or more.

More like at least 4000 times the Earth's mass. Jupiter is about 318 times the Earth's mass, and a minimum brown dwarf is around 13 times the mass of Jupiter. Yes, we would see something like that coming for quite some time, so, for example, the 2012 Planet X idea just won't work.

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Disclaimer: Avatar is not an official NASA image and does not imply any specific interplanetary or interstellar capability.

The Leif Ericson Cruiser

Uh, and what does mass have to do with visibility?

According to Saumon & Marley, a 10Gy minimum mass brown dwarf would have a surface temperature of less than 300K and a total log luminosity of about -6.5. What would its expected detection distance be?

Remember when you said this?
Were you talking about a brown dwarf, or an earth mass object, because it makes a big difference in how soon one or the other may be spotted on a survey. Obviously the much more massive dwarf is going to have a larger radius. Bigger things are easier to "see" than smaller ones.
I should have also mentioned, that a star heading directly at us is likely to have a large negative radial velocity and thus once again be noticed.

As to your second, question, I don't know without researching it further. By the way, your link is broken - it has "http://" repeated twice.

ETA: I will say, that a temperature of 300K must be a theorectical value. I don't think we have discovered anything nearly that cool. Of course you did say, surface temperature.

When I referred to a brown dwarf, I was talking about a brown dwarf, and when I spoke of an Earth mass object I was talking about an Earth mass object. I'm sorry if my segue was too quick for onlookers to follow.

How many stars are visible with current technology? a few billion? how often are radial velocity measurements made per visible star? Current radial velocity measurements are mostly done in the optical with near IR emerging. Such an brown dwarf would be dark in these bands.

Thanks, I will fix it.

Yes, objects like that would be very hard to detect, wouldn't they?

A cool brown dwarf is quite a favorable case from a detection standpoint. A same size "free" gas giant would have a mass a little less than Jupiter's and could plausibly be 30K or less. You'd be relying on reflected light to pick it up. A planet about the mass of Earth would be ~100 times dimmer in reflect light yet could change Earth's orbit if it (very unluckily) passed close enough. If it bumped e to 0.05, I'm pretty sure we'd notice the effect on the climate. Maybe one of the real astronomers can tell us what magnitude object would be certainly detected as interesting. If a magnitude 20 star appeared, not in the ecliptic, would alarm bells be ringing? I doubt it.

I'm not sure what the significance of the detection distance is anyway. The OP didn't state a limit. It matters little if we detect a planetary or greater mass intruder at 10AU or 10,000AU. We cannot stop it.

It's interesting to speculate on the frequency with which stellar systems are disrupted by intruders. Obviously ours is undisrupted in four billion years, but the anthropic principle tells us that this observation is of no value. Looking at other stellar systems we see.... a lot of eccentric orbits.

That was not at all clear from your statement, so I'd suggest being less snippy. We've had many people that have asked about brown dwarfs and dwarf planets in a similar manner, such as talking about a brown dwarf "Planet X" in one sentence, then following it up with a comment about Eris in the next.

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I say there is an invisible elf in my backyard. How do you prove that I am wrong?

Disclaimer: Avatar is not an official NASA image and does not imply any specific interplanetary or interstellar capability.

The Leif Ericson Cruiser

Note that I was responding to Veeger here, but more massive objects will tend to be hotter. Also, more massive objects will cause perturbations at a greater distance than lower mass objects, and this gives some limits to how close an object could be. From "Constraints on the Acceleration of the Solar System from High-Precision Timing" (note - PDF file):

That's Jupiter mass. As a brown dwarf would have at least 13 times that much mass, the minimum distance would be greater.

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I say there is an invisible elf in my backyard. How do you prove that I am wrong?

Disclaimer: Avatar is not an official NASA image and does not imply any specific interplanetary or interstellar capability.

The Leif Ericson Cruiser

A brown dwarf in the Oort Cloud would have been discovered by now
via reflected sunlight. An Earth-size planet anywhere closer than the
Oort Cloud would also have been discovered.

The main things that would make such objects pop out are the
motions due to the fact that they could not be headed directly for
Earth (though they could be headed directly for the Sun), and the
annual motion due to parallax from Earth's orbit.

I assumed in my reply that the original poster would want the events
to occur in as near a future as possible, as that would likely be more
interesting to most readers. Since we know that there are not any
large planets or larger bodies headed toward us that could reach us
in less than a hundred years at a plausible speed, that removes them
from the list of plausible causes of a cataclysm in the near future.

-- Jeff, in Minneapolis

__________________
http://www.FreeMars.org/jeff/

"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves

3.6 times greater. It's nice to know that there isn't one there now. A 1 M_J 1000kms^-1 hypervelocity object would cover 200AU in a little under a year. Unless they repeat the study annually it would provide no warning of the approach of such an object. An Earth mass object would not be detectable by this method until it were 11AU away.

I note that Zakamska and Tremaine's method is more sensitive to the presence of a distant companion (300–400 AU) than existing optical and infrared surveys, so we can forget the idea that an intruder would be detected at 10,000 or more AU by optical or IR means as some have suggested.

Now this is an interesting paper, thank you for posting it. I will read it in much more detail today.

Have you done the calculation? [You're as good at this as I am. Remember to use the inverse fourth law for reflected light.] Calculate the distance from the Sun Jupiter would have to be moved to drop beyond the HST's mag. limit (31). You should get about 10,000 AU, which is well within the Oort Cloud.

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No, I haven't. I'm just going on what I recall about discussions
of Nemisis and Nibiru and Nancy's Planet X, the latter of which I
participated in, and magazine articles on detection and discovery
of Kuiper Belt objects, brown dwarfs, and extrasolar planets.

Actually, HST's limit is way beyond what should be expected for
recent comprehensive surveys. Maybe 18th or 20th magnitude.
To find anything much beyond that would be due as much to
luck as to systematic observation, simply because of the limited
coverage of deep-field images, whether by HST or scopes on
the ground.

-- Jeff, in Minneapolis

__________________
http://www.FreeMars.org/jeff/

"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves