Starship Asterisk*

Without oceans of water, Earth will simply be another piece of dry rock orbiting a star. If the water on Earth (Moon and Mars) is proven to have originated from around the orbit of Jupiter, then by extension, this is where life in our Solar system came from. Scientists are searching for Earth like planets in "circumstellar habitable zones" defined in Wikipedia as:

In astronomy and astrobiology, the circumstellar habitable zone (CHZ) (or simply the habitable zone), colloquially known as the Goldilocks zone, is the region around a star within which planetary-mass objects with sufficient atmospheric pressure can support liquid water at their surfaces.[1][2] The bounds of the CHZ are calculated using the known requirements of Earth's biosphere, its position in the Solar System and the amount of radiant energy it receives from the Sun. Due to the importance of liquid water to life as it exists on Earth, the nature of the CHZ and the objects within is believed to be instrumental in determining the scope and distribution of extraterrestrial life and intelligence.

From "A Taste of Comet Water" - http://science1.nasa.gov/science-news/s ... ote]Comets born near Jupiter are rare today because the giant planet's gravity long ago flung most of them into interstellar space. Nevertheless, they would have been numerous during the solar system's formative years. Astronomers think the primordial Earth would have intercepted more comets from the "Jupiter zone" (which is comparatively poor in heavy water) than ones that formed in the outer solar system (which is rich in heavy water).
see captionThe "Jupiter zone" received more light and was warmer than the outer solar system. As a result, more reactions occurred in the gas near Jupiter and greater amounts of many complex organic molecules were available to wind up in comets. Also, Jupiter's powerful gravity kept collision speeds between comets near it high, preventing them from growing very large. Both factors may have given a boost to life on Earth.
Right: Comets born near Jupiter may contain the right flavor of water to explain Earth's oceans.
"It's like being hit by a snowball instead of an iceberg," said Mumma. "The smaller comets from Jupiter's region impacted Earth relatively gently, shattering high in the atmosphere and delivering most of their organic molecules intact. Such comets would have had a greater portion of life's building blocks -- the complex organic molecules -- to begin with. This means life on Earth did not have to start completely from scratch. Instead, it was delivered in kit form from space."[/quote]

Reading these two articles together I can not help but wonder. Should our scientists not include presence of Jupiter like extra solar planets within the habitable zone a very important parameter in the search for Earth like planets? We could even go further as to suggest that finding Jupiter like planets within the circumstellar habitable zones is the primary indicator of finding an Earth like (not just Earth size) planets with high probability of having oceans of water supporting Life as we know it.

ErnieM wrote:Without oceans of water, Earth will simply be another piece of dry rock orbiting a star. If the water on Earth (Moon and Mars) is proven to have originated from around the orbit of Jupiter, then by extension, this is where life in our Solar system came from.

How so? The most likely scenario is that water came from comets, but life developed on Earth.

Reading these two articles together I can not help but wonder. Should our scientists not include presence of Jupiter like extra solar planets within the habitable zone a very important parameter in the search for Earth like planets? We could even go further as to suggest that finding Jupiter like planets within the circumstellar habitable zones is the primary indicator of finding an Earth like (not just Earth size) planets with high probability of having oceans of water supporting Life as we know it.

It isn't necessary to have a massive planet in the habitable zone. Assuming that you need a massive planet to provide the necessary comet bombardment of terrestrial planets, that planet can certainly be well outside the habitable zone.

Chris Peterson :

1. How so? The most likely scenario is that water came from comets, but life developed on Earth.

2. It isn't necessary to have a massive planet in the habitable zone. Assuming that you need a massive planet to provide the necessary comet bombardment of terrestrial planets, that planet can certainly be well outside the habitable zone.

1. Allow me to repeat what the article says:

"It's like being hit by a snowball instead of an iceberg," said Mumma. "The smaller comets from Jupiter's region impacted Earth relatively gently, shattering high in the atmosphere and delivering most of their organic molecules intact. Such comets would have had a greater portion of life's building blocks -- the complex organic molecules -- to begin with. This means life on Earth did not have to start completely from scratch. Instead, it was delivered in kit form from space."

There is no argument that life as we know it is developing to maturity on Earth, but maybe courtesy of the complex organic molecules supposedly contained in theses comets.

2. Jupiter and Saturn have several moons. If they happen to be in the habitable zone, some of their icy moons would have Life sustaining oceans. I believe searching for Earth like, life sustaining environments (planets and moons) is the main objective.

There's just a lot of hype around the only vague idea that life started off planet Earth right now. Of course the molecules themselves have a long, varied and mysterious history prior to their arrival at Earth but there is really nothing to substantiate any statements that sound even remotely like life started from around Jupiter, which is what you said, Ernie. Or, at least, that's what it sounded like you said. Complex molecules surely ≠ life. You have me imagining comets floating around with simple life on them and delivering them to a young Earth. That doesn't make much sense because supposedly any life on a comet would be exposed to radiation which would easily destroy information transmitting molecules like DNA. And if they aren't exposed to radiation, where are they getting energy? I suppose the possibility can't be discounted entirely but it seems a lot more plausible that early life would have had a much more comfortable, sheltered start on Earth.

geckzilla wrote:There's just a lot of hype around the only vague idea that life started off planet Earth right now. Of course the molecules themselves have a long, varied and mysterious history prior to their arrival at Earth but there is really nothing to substantiate any statements that sound even remotely like life started from around Jupiter, which is what you said, Ernie. Or, at least, that's what it sounded like you said. Complex molecules surely ≠ life. You have me imagining comets floating around with simple life on them and delivering them to a young Earth. That doesn't make much sense because supposedly any life on a comet would be exposed to radiation which would easily destroy information transmitting molecules like DNA. And if they aren't exposed to radiation, where are they getting energy? I suppose the possibility can't be discounted entirely but it seems a lot more plausible that early life would have had a much more comfortable, sheltered start on Earth.

Certainly once the water and atmosphere formed on Earth.

I'm not a believer in primitive life on comets et al, though I'm open to someone/something convincing me otherwise.

Nitpicker wrote:

geckzilla wrote:

There's just a lot of hype around the only vague idea that life started off planet Earth right now. Of course the molecules themselves have a long, varied and mysterious history prior to their arrival at Earth but there is really nothing to substantiate any statements that sound even remotely like life started from around Jupiter, which is what you said, Ernie. Or, at least, that's what it sounded like you said. Complex molecules surely ≠ life. You have me imagining comets floating around with simple life on them and delivering them to a young Earth. That doesn't make much sense because supposedly any life on a comet would be exposed to radiation which would easily destroy information transmitting molecules like DNA. And if they aren't exposed to radiation, where are they getting energy? I suppose the possibility can't be discounted entirely but it seems a lot more plausible that early life would have had a much more comfortable, sheltered start on Earth.

Certainly once the water and atmosphere formed on Earth.

I'm not a believer in primitive life on comets et al, though I'm open to someone/something convincing me otherwise.

I simply suggest a simple Google search for "complex molecules in the solar system".
In "The Early Solar System" Mr. Cowen wrote:

Huge impacts on the early Earth would have wiped out any life or proto-life on the planet. The life forms that were our ancestors could not have evolved until after the last sterilizing impact. Smaller late impacts may have encouraged the evolution of life, as comets and meteorites fell on to Earth from space. All comets and a few meteorites carry a significant proportion of organic molecules, and comets may have been a major source of the organic molecules that made possible the evolution of life on Earth.

Did these comets and meteorites come from around Jupiter? I do not know. To be clear. What I said was:
"If the water on Earth (Moon and Mars) is proven to have originated from around the orbit of Jupiter, then by extension, this is where life in our Solar system came from."

ErnieM wrote:Did these comets and meteorites come from around Jupiter? I do not know. To be clear. What I said was:
"If the water on Earth (Moon and Mars) is proven to have originated from around the orbit of Jupiter, then by extension, this is where life in our Solar system came from."

Yes, and to be clear, that's the statement I disagree with.

Ingredients for life coming from outside the already developed Earth is very different than life coming from there. The carbon in my body came from another star. The hydrogen in my body came from the Big Bang. That does not mean I came from either.