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Earth's Collision With A Mercury-Like Planet May Have Been Vital To Life Flourishing

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http://www.independent.co.uk/news/science/earths-collision-with-a-mercurylike-planet-may-have-been-vital-to-life-flourishing-scientists-say-10179232.html

A massive collision between a Mercury-like planet and the early Earth could have taken place billions of years ago to create the vital planetary conditions that have allowed life to flourish, a study has suggested.

An analysis of the elements making up the Earth’s crust and mantle suggest that such a collision in the distant past could help to account for the heat of the planet’s core. It is this heat that drives the movement of molten iron at the centre of the Earth, which generates the magnetic shield protecting the planet against damaging cosmic radiation.

Scientists said the crust and mantle contain a higher ratio of samarium to neodymium – two rare-earth metals – than what is seen in meteorites. This suggests that something else happened during the early collisions of the Earth other then the continual bombardment by meteorites.

One intriguing possibility is that a Mercury-like body, which was rich in sulphur, became incorporated into the Earth following a gigantic collision. This sulphur would have helped to trigger chemistry that led to the balance of samarium to neodymium seen today, the scientists said.

More importantly for life on Earth, the collision and the addition of sulphur to the early planet would have generated the source of heat that drives the “geo-dynamo” responsible for creating the planet’s magnetic field, which protects against cosmic radiation from space and allows liquid water and life to exist at the surface.

Yet more odds to factor into if life exists on another planet??

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Just more made up stuff from scientists.

Its just the classic conjecture and refutation. Not quite sure how its possible to refute any of this stuff though.

No lose situation. Just fire out paper after paper on random things. Nobody is really ever going to be able to 'prove' you wrong.

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Why is it that life on Earth had to be caused by something else - a meteor, an asteroid, another planet?

Any day now they will be asking the Earth to apologise for colliding with whatever it is it is supposed to have collided with.

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Just more made up stuff from scientists.

Its just the classic conjecture and refutation. Not quite sure how its possible to refute any of this stuff though.

No lose situation. Just fire out paper after paper on random things. Nobody is really ever going to be able to 'prove' you wrong.

I believe the expression is 'Publish or Perish'

http://en.m.wikipedia.org/wiki/Publish_or_perish

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Why is it that life on Earth had to be caused by something else - a meteor, an asteroid, another planet?

Any day now they will be asking the Earth to apologise for colliding with whatever it is it is supposed to have collided with.

I think it's been driven by the suspicion that we (our solar system) are more unique than we originally expected.

Since the discovery that you can "see" planets orbiting disant suns showing their size, orbit, position and atmospheric composition I think scientists are building up a picture where our particular solar system is fairly unique.

There was a very good Horizon documentary on it a while back.

http://www.bbc.co.uk/programmes/b05527mp

Since there is not much sign of life out there I think there is a lot of speculation about why we were different..

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I think it's been driven by the suspicion that we (our solar system) are more unique than we originally expected.

Since the discovery that you can "see" planets orbiting disant suns showing their size, orbit, position and atmospheric composition I think scientists are building up a picture where our particular solar system is fairly unique...

I'm afraid there are no degrees of uniqueness. Either you're unique or you're not.

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Or maybe it was a Mars-like, as opposed to a Mercury-like planet

wiki: Theia (planet)

The suggestion that the Earth was walloped by something large, early on, which gave rise to plate tectonics, it's magnetic field and the the Moon is not exactly new.

Postulated impacts are dead handy when your sums don't add up. You can whistle one up to fill in gaps in a pet theory, instead of starting from scratch.

In fairness to Earth science, for most of its history geologists pretended catastrophes didn't have much impact on the development of the Earth. It was all a bit too Biblical. Which was a bit silly as the rock record is dripping with catastrophes. So, there's a lot of catching up to do. I believe the new paradigm is sometimes referred to as 'neocatastrophism' to distinguish it from Genesis.

I'm old enough to remember Earth science lecturers who were still putting the boot into Immanuel Velikovsky. So I find the turnaround in thinking over the last few decades vaguely amusing.

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Since the discovery that you can "see" planets orbiting disant suns showing their size, orbit, position and atmospheric composition I think scientists are building up a picture where our particular solar system is fairly unique.

Although there's quite a degree of observation bias, since it's much easier to detect large planets close to stars.

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Even though extrasolar planet discovery is turning up lots of stellar systems that aren't likely to be able to support Earth-like planets one thing it has done is significantly increase the number of planetary systems; IIRC it's showing that they're more common than was expected, which surely increases the chances of a really interesting one existing somewhere.

The whole "discovering planets around other stars" thing is one of the most interesting things going on these days IMO, and I still find it incredible that we can do it at all.

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I would hope they still are.

On specifics he was a loon.

On the general suggestion that comets and such have shaped our ecosystem he'd pass off as being borderline orthodox these days.

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Even though extrasolar planet discovery is turning up lots of stellar systems that aren't likely to be able to support Earth-like planets one thing it has done is significantly increase the number of planetary systems; IIRC it's showing that they're more common than was expected, which surely increases the chances of a really interesting one existing somewhere.

The whole "discovering planets around other stars" thing is one of the most interesting things going on these days IMO, and I still find it incredible that we can do it at all.

Venus is in the goldilocks zone, almost a perfect size and dead close (astronomically). Presumably we just need to tidy up the atmosphere a bit and we're laughing.

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Venus may well have been inhabitable once in the dim and distant past. A bit of extra heat and the oceans ending up in the atmosphere fits (particularly as stars on the main sequence heat up gradually over their lives).

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Venus may well have been inhabitable once in the dim and distant past. A bit of extra heat and the oceans ending up in the atmosphere fits (particularly as stars on the main sequence heat up gradually over their lives).

codswallop. Venus is no Earth, nor ever was.

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codswallop. Venus is no Earth, nor ever was.

And you base that on what? The idea that it couls've been inhabitable is of course just conjecture but not so unfounded as to make such a strong denial reasonable.

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And you base that on what? The idea that it couls've been inhabitable is of course just conjecture but not so unfounded as to make such a strong denial reasonable.

You want a list of the basic pre-requisites of Earth's biosphere? Its a long list.

"Goldilock's zone" is a joke.

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No, it's not a joke, it's one fairly significant pre-requisite. No-one's claimed it's the only one. Surface water on Venus a long time in the past is quite plausible. Inhabitable is not the same as inhabited. Sure, there are problems, such as the lack of a magnetic field, but still nowhere near enough to justify such a definite "no".

Saying "the probability of life in the past on Venus is high" cannot be supported. Neither can so strongly denying it.

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No, it's not a joke, it's one fairly significant pre-requisite. No-one's claimed it's the only one. Surface water on Venus a long time in the past is quite plausible. Inhabitable is not the same as inhabited. Sure, there are problems, such as the lack of a magnetic field, but still nowhere near enough to justify your reaction to the very suggestion.

get your chops around this (probably far from comprehensive) list:

http://en.wikipedia.org/wiki/Rare_Earth_hypothesis#Rare_Earth.27s_requirements_for_complex_life

My extreme reaction is to nonsensical "Goldilocks" statements from the likes of NASA (seeking funding) and media (seeking readers) exploiting public ignorance. Gerry Faldwell would be embarrassed to make such claims advancing the existence of a supreme Being.

Science Groupies, don't you love 'em?

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You want a list of the basic pre-requisites of Earth's biosphere? Its a long list.

"Goldilock's zone" is a joke.

Goldilocks zone is just a first order approximation. From what I can see a planet has to be a certain distance from a star in order for liquid water to be able to exist on its surface.

Funnily enough though there are places that are widely spaced in the solar system where liquid water could exist. Examples might be Mercury, where ice is know to exist and water therefore may exist in transition zones and Enceladus that is thought to have a sub surface ocean.

"Goldilocks Zone" is not a joke, it's part of the beginning of the process of learning to classify exoplanets and their suitability to support life. As an approximation, it may be pretty crude, but that's what science is about, and over time the crude theories we have at the moment will be refined and improved.

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get your chops around this (probably far from comprehensive) list:

http://en.wikipedia.org/wiki/Rare_Earth_hypothesis#Rare_Earth.27s_requirements_for_complex_life

My extreme reaction is to nonsensical "Goldilocks" statements from the likes of NASA (seeking funding) and media (seeking readers) exploiting public ignorance. Gerry Faldwell would be embarrassed to make such claims advancing the existence of a supreme Being.

Science Groupies, don't you love 'em?

Now you're going on about complex life. The "Goldilocks zone" is about liquid water, a pretty important necessity before you start to even consider anything else so the rants about it being nonsensical and a joke are making you look like you've got a chip on your shoulder. You'd have a point if it was as simple as "liquid water might be possible there, there'll almost certainly be life" but no-one is claiming that.

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Now you're going on about complex life. The "Goldilocks zone" is about liquid water, a pretty important necessity before you start to even consider anything else so the rants about it being nonsensical and a joke are making you look like you've got a chip on your shoulder. You'd have a point if it was as simple as "liquid water might be possible there, there'll almost certainly be life" but no-one is claiming that.

Goldilocks Zone actually acts as a sort of filter.

I don't think many people would argue it is that accurate at predicting life. However, quite a few people would argue that since the earth has life, if we want to look for other planets that might have life, finding ones similar to earth, ie have liquid water on the surface might be a good place to start.

Now after Kepler we have discovered about 1000 exoplanets. Which is far to many to study in detail.

But if you were going to choose where to point your giant space telescope to do spectroscopy and try to discover whether a planet has life signatures in its atmosphere, do you point it at exoplanets like Jupiter, or small rocky planets like earth that orbit a distance from their star where theoretically water should exist on the surface ?

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