An object the size of mars hit earth?

[origin]

I can always tell the exact time when a forum topic is linked to the SDC front page

I wondered if that was what happened. The thread got very, um, interesting out of the blue last night.

 

[Drusillus]

Kind of why they are called theory's. Sure there isn't definitive proof of a giant impact resulting in our moon and our planets rotation.

But, there has been countless hours of research by a lot of very intelligent people to bring this theory to the table.

It is currently the most accepted theory to explain our moon. For the OP to disagree without looking further into the research and documentation on this theory is very naive.

 

[rlb2]

CommonMan wrote - Could the Mars sizes object that hit Earth really been Mars? If not where did it go? Shouldn’t it still be in orbit somewhere around the Sun? Just a question. Don’t shoot me if it sounds stupid Wayne

I have been posting just that for several years, half of Mars has been said to be hit by a giant asteroid billions of years ago according to Steve Squyres Cornel University, well I think its northern shape is from hitting earth.

Here is how I think it could happen.

During the formation of the solar system billions of years ago Mars had an even larger elliptical orbit, more like a comets. At that time as the solar system was forming Earth and Mars had similar material. Mars speed around the sun was similar to what it is today but varied more because of its highly elliptical orbit averaging 24 km/s where earth's orbit was similar to what it is today with an average speed of 30 km/s. Earth struck Mars at approximately 30 km/s - 24 km/s = 6km/s as it was orbiting the sun. Earth's size at that time was apx. 1.1 times larger than it is today. Mars being the smaller world carved a big gaping part out of earth creating the Moon, see image below, much like someone taking a bite out of an apple. Mars and Earth angular momentum, rotation rate, was re-set after the collision.

Edited Image only..

 

[MeteorWayne]

Of course, you have no mathematical support for that unrealistic scenario, while the Giant Impact theory has been well vetted and examined by dozens of researchers for decades

 

[SpecialEd]

A couple of things that I've not seen mentioned yet is that any theory involving the evolution and devolopment of a planetary system has to account for both the uniqueness and non-uniqueness of any planet in it. Namely involving large collisions. If every terrestrial planet were to have had such a collision early in its development like what the Ur-Earth got, they'd also have a large moon.

They don't.

Mars has a couple of very small moons, very much most likely captured asteroids while the two inner planets have none... but interestingly, Venus has a very slow rotational rate, so slow it's going in reverse! ... so the joke goes. Anyway, a sizeable collision between the Ur-Venus and a large, maybe 'Mars-ish' body could have caused that slow rotation rate, just as Uranus seems to have been 'knocked on its side' by an Earth-mass impactor.

So it seems as if early collisions did/could have occured in the early years of the solar system, not just for Earth, but Venus and Urans as well. The proof is in the skies!

Otherwise, tell me how something as massive as Uranus formed with it's axis of rotation whammied like that (not to mention the oddness of its magnetic field! Hmm... Neptune's odd as well... hmm...) or how Venus could develop with such a slow, retrograde rotation. I don't think that tidal effects from Sol would be enough to do that to Venus. :ugeek:

 

[rlb2]

MeteorWayne wrote - Of course, you have no mathematical support for that unrealistic scenario, while the Giant Impact theory has been well vetted and examined by dozens of researchers for decades

rlb2 reply - Too many similarities not to be considered as a viable hypothesis. The speed of impact of Mars / Earth would be about the same as the model forecast, mars entire northern hemisphere is said to have been carved out by a huge impact as stated above making it the largest impact in the solar system. etc,etc...

Unlike you I'm not trying to take over the world I am just trying to figure it out.

 

[MaxWithershins]

Theory = hypothesis = "a supposition made on the basis of limited evidence as a starting point for further investigation" (operative words "limited evidence") = a semi-educated guess = we don't know.

This is the fifth fairly recent theory suggesting how the moon may have been formed. And while it is currently the "favored" theory, it is still just a theory, and I can't help wondering what the next one will be. The only thing we know for sure (or **can** know, until someone figures out how to travel through time!) ... is that we will never know for sure.

So how about the theory that the Earth used to have more than one moon? Anybody want to waste some time guessing about whether that's true or not?

Forward, folks. ;-P

 

[drwayne]

Actually, a theory and a hypothesis are not the same thing.

"A hypothesis attempts to answer questions by putting forth a plausible explanation that has yet to be rigorously tested. A theory, on the other hand, has already undergone extensive testing by various scientists and is generally accepted as being an accurate explanation of an observation. This doesn’t mean the theory is correct; only that current testing has not yet been able to disprove it, and the evidence as it is understood, appears to support it."

http://www.wisegeek.com/what-is-the-dif ... thesis.htm

 

[FlatEarth]

Wow, does anyone think that this event would have had any effect on earths biological beginning/ evolution? Did it just put it back by a millenia or two or did it aid the building blocks of life? Apologies if stuipid question, but unlike first post, I recognise my own ignorance in some matters and have an open mind. I'm not a creationist but the narrow band of environmental variables needed to sustain (human?) life on earth does seem statistically improbable, or is that a myth? How would this event add/ detract to the statistical probability of life on earth?

It did indeed have an effect on biological evolution. The original collision that formed the moon increased the mass of Earth while also increasing its rotation to 24 hours, thereby limiting the variation of temperature from night to day and establishing the weather patterns that we now have (along with other factors, of course). The moon acts to stabilize the rotational axis of Earth, in essence eliminating much of the wobble in its rotation and creating consistent seasons and a more stable environment. There is still a wobble present, but it is much less extreme and on a longer cycle than if there were no moon. The effects of the moon on our oceans is thought to break up the tidal effects of the sun, preventing a destructive tidal build up (I may not have this exactly right). This stability associated with the moon certainly contributed to the evolution and survival of our species.

 

[aaron38]

Yea, the most modern theories on Moon formation seem to say yes it did happen. But can I ask a question. What happened to the Mars size object, afterall the Earth is still around? Does this mean that the Earth was once much smaller and the "new" Earth & the moon are a composite of the "old" Earth and a Mars size planet obliterated upon impact? :?

A Science Channel show talked about this last week, it was different that I would have guessed. Basically, as the early Earth was forming, the debris in Earth's orbit did not all gather into one planet, but first into two. There was the early Earth with an Earth minus Mars mass, and a second planet, named Theia, with the mass of Mars, located at the Trojan point in Earth's orbit. This was not a stable orbit for Theia, and it wobbled until it fell out of the Trojan point and hit the Earth. But Theia was not flying through the solar system, it was in Earth's orbit, going around the Sun in the same direction at about the same speed, so it was a "moderate" speed collision. Because Theia formed from the exact same ring of debris that formed the Earth, this explains why we don't see different materials from an object that formed elsewhere in the solar system.

The show had a simulation, and I don't know how accurate it is, but in showing the collision, the core of Theia plunged straight down to merge with Earth's core, a bunch of mantle was ejected to form the moon, but the entire crust was not disturbed, only maybe 1/4th. And with the crust at that point being so young and thin, the impact point has been completely erased by plate techtonics.

 

[Bill_Wright]

Bill's Theory on Thea's Fate:
1) some of Thea merged with the proto-Earth
2) some of Thea condensed with the Moon
3) some of Thea has become NEOs
4) some of Thea got pulled into the Sun
5) some of Thea got tugged by Jupiter and Mars into the Asteroid Belt

There is insufficient data to compute the quantities for each category.

 

[andrew_t1000]

Is the Atlantic mass anomaly a remnant of this event?

 

[Dissident]

It was all created by god!

I hear your brains all screeching to a halt as you switch to attack mode, just relax, I don't believe that.

Anyway, I'm new here, by way of introduction I hold a doctorate in psychology, so I am not an astrophysicist, however, I have been alarmed by this field of late. Humanity seems to have made science the new infallible religion, theory has become the new scripture, and sadly, much theory in the field of astrophysics holds just as little tangible evidence as religion. A model, constructed under nominal conditions can in no way prove anything, it merely represents a possibility, so you shouldn't have attacked the original poster for being skeptical, this behavior by the scientific community lately has saddened me. We in the psychology community don't accept Freud or Jung as writing absolute truths, and without absolute proof that a mars sized body collided with Earth, I don't feel it was justified to attack the OP. If we fail to keep our minds open to challenging theories that can't be absolutely proven, we fail both science and society, and prepare ourselves for another dark age. I'm sorry, I just felt like I had to say that after seeing the mockery and near fanatical assault on the original poster. Keep reaching for the stars, but with open minds, science holds few absolute truths.

 

[drwayne]

Welcome to the forum. Please note that it has been establisehed that I am beyond help in
the area of mental ---- health.

"much theory in the field of astrophysics holds just as little tangible evidence as religion"

This is a very strong, definitive statement from someone who started with a statement about not being someone
"in the field"*. Was that intended as a rheotorical flourish?

I'm not picking on you - I am just fascinated with the pattern of of

I'm not an expert in this field but (insert strong statement**).

Wayne

*I am a Ph.D. physicist, but I consider a lot of material, including cosmology as being outside my field as well.
Because, well, it is.

**Your strong statement did not involve giant worms on Mars, which was noted to your extreme credit

 

[Dissident]

Yes, I meant it as a rhetorical flourish more or less. My interest in space is passing, however, there is little definitive proof and only theory from what I have seen of the science. I do hold the belief that there are few absolutes, as supported by theories changing with time. That's not to say the science isn't good, but again, it was once thought the Earth was flat and sun orbited us, and I'm sure that was based on the best science of the time.

From my own background, Sigmund Freud was considered brilliant once, now he's become something of a joke. Who knows, in a hundred years time, Einstein may well be the joke of your community.

 

[drwayne]

"From my own background, Sigmund Freud was considered brilliant once, now he's become something of a joke."

Actually, such things sometimes have a weird oscillatory nature - as a function of time some individuals oscillate
between hero and zero, sometimes multiple times in one's own lifetime.

It is also interesting how someone can make a breakthrough in a field with an idea that seems ingenious at
the time, and have school kids some years later refer to it as if it was obvious...

Sorry for the tangent...

 

[MeteorWayne]

Before we get back on topic, I might suggest that the original poster's attitude ("It's the dumbest thing I've ever heard")
from an admitted non expert also caused the response to be pretty strong. If you admit you don't know anything about the subject, then basically say everyone who does is dumb, you're going to get peoples hackles up.

As a psychology major, you should understand that

In fact, I thought my response, unlike the poster, was quite mature and restrained.

 

[drwayne]

"Who knows, in a hundred years time, Einstein may well be the joke of your community."

I think because of his iconic status, we get a surprising number of folks who appear and make statements
along the lines of

"Albert wasn't so smart, he didn't consider *insert silly statement*"

In general though, being proved wrong seldom makes one a joke. (Myself excluded of course)

 

[majornature]

I'm probably late on this discussion topic, but if the theory did suggest that earth was hit by a mars-sized object and survive, chances are, the Earth would surive again if a mars sized object hit it. The beings living on this planet may not survive but the Earth will. She may embrace a new face, but she'll still be the same ol' gal! :mrgreen:

I see things haven't change since I was gone. Flying off from the far end of the universe. :lol:

 

[FlatEarth]

It was all created by god!

I hear your brains all screeching to a halt as you switch to attack mode, just relax, I don't believe that.

Anyway, I'm new here, by way of introduction I hold a doctorate in psychology, so I am not an astrophysicist, however, I have been alarmed by this field of late. Humanity seems to have made science the new infallible religion, theory has become the new scripture, and sadly, much theory in the field of astrophysics holds just as little tangible evidence as religion. A model, constructed under nominal conditions can in no way prove anything, it merely represents a possibility, so you shouldn't have attacked the original poster for being skeptical, this behavior by the scientific community lately has saddened me. We in the psychology community don't accept Freud or Jung as writing absolute truths, and without absolute proof that a mars sized body collided with Earth, I don't feel it was justified to attack the OP. If we fail to keep our minds open to challenging theories that can't be absolutely proven, we fail both science and society, and prepare ourselves for another dark age. I'm sorry, I just felt like I had to say that after seeing the mockery and near fanatical assault on the original poster. Keep reaching for the stars, but with open minds, science holds few absolute truths.

The original poster deserved the critical responses to his statements. His skepticism is based on an improbable set of circumstances, and he offered no alternate logical explanation for the formation of the moon. Since we can't go back in time to witness the formation of Earth, the next best thing is to create a computer simulation that results in what we see today. It's pretty obvious the Mars sized merger is the most likely scenario that led to our system.

I do agree with you that there exists a pattern in the scientific community, including satellite groups such as SDC, that resists independent thought. There is a tendency to be too focused on accepted theory, and any deviation is rigorously rejected. The purpose of a forum should be to exchange ideas and educate those who lack an understanding of the subject matter, but there is a point where some deviation from accepted knowledge should at least be entertained. This topic perhaps is not the best example of that, but certainly with subjects such as dark matter, dark energy, etc. there should be more room for independent thought.

 

[hemojr]

Does the Theia collision have anything to do with the "iron catastrophe" and the formation of the Earth's core as it exists today? I know that the iron catastrophe was hypothesized independent of the 'giant impact hypothesis.' However, it seems reasonable that the collision would ensure the conditions of an iron catastrophe (molten Earth at the same time as 95%?98%? of Earth's heavy elements already here) and could help explain why neither Venus nor Mars has quite the same structure. It's just that I don't see the two ideas synergized.

Well, in a sense yes, since apparently, much of the impactor's core would up in earth, so is part of our core. And the earth's core is larger than it otherwise would have been. However, the "iron catastrophe" (I've never understood that name. What was so catastrophic???) occurred about a half a billion years later, so it is only indirectly related, IMHO.

How hard a date is that for the iron catastrophe? The Theia collision would have caused the entire Earth to have become molten and 500my seems a rather long time for the nickel/iron to make it to the core.

My understanding is that the iron catastrophe theory relies the potential energy released by the sinking of heavy elements to heat the planet to the point where silica (lighter materials) of the Earth became entirely magma. Factoring in the heating from the impact of Theia, this postulated mechanism for magma globalization becomes redundant.

Anyway, it seems like a good thesis topic.

 

[blongsiab]

When I first heard of this I laughed it off. But after reconsidering all the possible things I find that it's possible. like balls on a pool table if you hit it straight on the the impact would have be as someone would say here but if you hit it just at an angle enough to cause the earth spine to go faster. Just enough so that some materials fly off far enough to stick together to become a moon and the rest falling back to earth. :|