The Uniqueness of Planet Earth

There seems to be a flood of news about the discovery of exo-planetary systems these days.

So many stars have been discovered to have planets revolving around them that some question, how many don't? Probably the vast majority of them do. Which means out of the hundreds of billions of stars in our local Milky Way Galaxy there are probably many more planets, perhaps trillions. So surely finding life on another planet like earth must be quite simple.

But is it quite that simple? There are many factors that makes our solar system so far unique in the galaxy that many people have not observed, and I thought I'd take the time and write about a few.

Firstly, our solar system is in an ideal spot in the Milky Way Galaxy. The Milky Way consists of more than one hundred billion stars. Most of these are clustered in the center of the galaxy that surround a supermasive black hole. From that center arms spiral outward. Our galaxy itself is one hundred thousand light years across.

If our solar system were too close to the center of the galaxy tremendous amounts of radiation would make life impossible. Likewise if it were too far out towards the edges, heavier elements that make life possible would be lacking. So we are in prime real estate, in our place in the galaxy. On the edge of an outer spiral arm, not too close to the center of the galaxy, but not too far out either.

The star our at the center of our solar system is classified as a yellow star. Most stars in our galaxy are much smaller. And most stars similar to ours are binary stars meaning one star orbits another. That would wreak havoc on any gravitational pull one star would have on a planet, leaving that planet's orbit irregular.

Interestingly enough all of the known stars classified as yellow stars in our neighborhood are all binary systems, and are made up of lighter elements.

Does anything else make our solar system stand out among the thousands of exo-planetary systems discovered to date? Yes. Two quite striking features that are hard to ignore:

One is the nearly circular orbit that our planets have around our central star, the sun. Almost all exo-planetary systems have very ecliptic orbits, not circular at all. Meaning that while at one point in their journey around their star the planet may pass close by its star at another point in its journey it may be very far out. Meaning that their would be frigged parts of the year much too cold to sustain life and parts of the year where it would simply be too hot for life to exist.

Two, is the position of our planets in the solar system seems to be unique. Not only are all of the orbits circular but the larger planets are in the outer solar system. Again almost uniformly all exoplanetary system discovered to date have huge planets in the inner solar system. Why does that matter?

If planets like Jupiter were closer to the sun they would pose a dramatic effect on the gravitational aliment of the earth and its orbit, leaving life virtually impossible to thrive as it would wobble back and forth.

Just yesterday a news report came out that said that collisions in the outer planets from comets and stray asteroids are much more common than earlier postulated. Link to Article

In fact the fact that the outer planets such as Jupiter and Saturn are so large is good for the earth. They act as a safety net catching debris that comes into our solar system. They actually act as barriers that protect the earth.

Are there any other factors that make the position of earth in our solar system unique? Yes!

Earth has the perfect neighbor. The moon is just over a quater the size of that of the earth. Therefore, in relation to size to the host planet, our moon is much larger than the rest of the moons (or natural satellites) in our solar system....

cont....

Also the moon is situated in just the right position that when it covers the sun it is a perfect match to it.

The size and position of our moon is also of great significance to life on earth. Its gravitational pull effects the ebbs and flows of the tides, which are believed to be vital for earth’s weather patterns.

Without our moon in place the scientific Journal Nature states that the inclination of earth’s axis would wobble over long periods of times from 0 degrees to 85 degrees. . “We owe our present climate stability to an exceptional event: the presence of the Moon,” concludes astronomer Jacques Laskar.
In fact without our moon the earth would wobble like a spinning top, and could possible even tip on its side, creating traumatic climatic and natural disasters such as tidal waves, and dramatic changes in the weather.

Also very important and unique among all other planets so far discovered is the position of earth in our solar system. It sits at a comfortable 93 million miles from the sun, and circles it in pretty much a circular orbit (already we have shown that this is almost wholly unique to our solar system).
Therefore we are not so close that the heat from our sun is unbearable, and yet we are not so far away that the temperatures are too frigid for humans.

The sun is perfect for our earth. It is a stable star. It neither shrinks nor grows in size. It doesn’t vary in intensity. It emits just the right amount of energy at all times. In fact because of this and many other reasons our sun has been called “a very special star.” – Perfect Planet, Clever Species – How Unique Are We? By William C. Burger, 2003, pp 24, 34.
Earth also has the perfect tilt and spin. Its tilt is about 23.4 degrees, which causes our annual seasons, moderate temperatures, and allows for a large variety of climates. “Our planet’s tilt axis seems to be ‘just right.’ – Rare Earth – Why Complex Life is Uncommon in the Universe by Peter D. Ward and Donald Brownlee, 2000, p. 224.

Because the spin of the earth is 24 hours each side of the earth gets equal amount of sunlight at just the right amounts. If it rotated any slower one side would bake while the other would freeze, while if it spun faster, the rapid spin would cause relentless gale-force winds and other harmful effects.
What about the earth itself?
We know that space is a dangerous place where deadly radiation is common place and meteorites are an ever present danger. Our earth is able to fly through this galactic danger zone with impunity. Why? Earth is protected by awesome armor – a powerful magnetic field and a custom-made atmosphere.

Take a look at our magnetic field.

At the center of our earth is a spinning ball of molten iron that causes a huge and powerful magnetic field that reaches far into space. This shield protects the earth from the full intensity of cosmic radiation and potentially deadly forces emanating from the sun; including solar wind, solar flares, and explosions in the corona of the sun which blast billions of tons of matter into space.

Earth’s atmosphereis a blanket of gases in our sky that not only keeps us breathing but gives us added protection. The outer layer of our atmosphere known as the stratosphere contains oxygen known as ozone that is able to absorb up to 99 percent of all ultraviolet light hitting earth. Thus our ozone layer helps protect not only humans, but also plankton, the form of life we most depend upon to produce most of earth’s oxygen. Furthermore ozone is not just static. It can actually change in size as the intensity of UV radiation changes. So the ozone layer is dynamic, a very efficient shield.

cont....

Of course earth’s atmosphere protects earth from a barrage of debris that rains down on us on a daily basis. The atmosphere while protecting us from dangerous debris, and radiation, allows beneficial light, and heat to get through. So it also serves as a filter that allows just the right amount of electromagnetic radiation needed for life through. Our atmosphere also helps to distribute heat, and acts as a blanket at night so the heat does not escape to fast into space.

These are but just a few of the very awesome facts that make the earth and its sun and the solar system we journey with it in around our Milky Way galaxy incredible.

So the next time you see a news story about a new exoplanetary system contemplate all of the aforementioned, and ask yourself. Have they found another system quite like ours?

reply to post by Calender


Ummm....ummm....a lot of flowery language, but filled with many incorrect assumptions and claims.

However, it has a ring of familiarity? I've read something very, very much like it before --- somewhere else?

You wouldn't happen to have a link to the source, where YOU read it, would you?

Thanks.

None of the aforementioned are spurious claims. I have no link to this as I just wrote it. Now, if you have proof to the contrary shoot away.

Originally posted by Calender
Of course earth’s atmosphere protects earth from a barrage of debris that rains down on us on a daily basis. The atmosphere while protecting us from dangerous debris, and radiation, allows beneficial light, and heat to get through. So it also serves as a filter that allows just the right amount of electromagnetic radiation needed for life through. Our atmosphere also helps to distribute heat, and acts as a blanket at night so the heat does not escape to fast into space.

These are but just a few of the very awesome facts that make the earth and its sun and the solar system we journey with it in around our Milky Way galaxy incredible.

So the next time you see a news story about a new exoplanetary system contemplate all of the aforementioned, and ask yourself. Have they found another system quite like ours?

Every Solar system and every planet out there is unique, asking that question is like asking if we will ever find another person that is quite like me. Yes you will find someone who resembles me and acts like me but he will not have the same DNA.

There is a planet out there that looks like Earth with Air like Earth and a Star like our sun, there is a chance that there is a Solar system very similar to ours but it won't be exactly like ours.

[edit on 26-8-2010 by Segador]

Originally posted by Segador

Originally posted by Calender
Of course earth’s atmosphere protects earth from a barrage of debris that rains down on us on a daily basis. The atmosphere while protecting us from dangerous debris, and radiation, allows beneficial light, and heat to get through. So it also serves as a filter that allows just the right amount of electromagnetic radiation needed for life through. Our atmosphere also helps to distribute heat, and acts as a blanket at night so the heat does not escape to fast into space.

These are but just a few of the very awesome facts that make the earth and its sun and the solar system we journey with it in around our Milky Way galaxy incredible.

So the next time you see a news story about a new exoplanetary system contemplate all of the aforementioned, and ask yourself. Have they found another system quite like ours?

Every Solar system and every planet out there is unique, asking that question is like asking if we will ever find another person that is quite like me. Yes you will find someone who resembles you and acts like you but he will not have the same DNA.

There is a planet out there that looks like Earth with Air like Earth and a Star like our sun, there is a chance that there is a Solar system very similar to ours but it won't be exactly like ours.

This is a statement of fact, meaning that it can be proven. Please prove to me there is another solar system out there that is similar to ours in every way mentioned above.

reply to post by Calender


Well....(not peeing all over your work, just quibbling with some of the more blatant assumptions. SOME things you mention are not up for argument, though. Like, the fact that WE are here, and our planet is fairly stable, because of our fortuitous Moon...but, it isn't as simple as all that, either...).


Early on, in just the opening post, I had a great deal of difficulty with this:

Firstly, our solar system is in an ideal spot in the Milky Way Galaxy.

??? Come on! No way to make a statement that absolute, because we KNOW LITTLE about the Galaxy!!

There is still much to explore, and discover. Our distance and remoteness? Nice, and useful for us..but there's a LOT of Galaxy too...

_________________________

What I'm trying to express is --- it is too soon to call "unique" on the Earth.

Granted, in a sense...it IS "unique", but only in the way of thinking that there is no "identical twin" out there. By that measure, all humans, each individual, is also "unique" --- doubt there's any argument there, yes?

The claims of the types of other stars, and such...again, it is taking a small, small local sample, and trying to "conflate" and "infer" to the rest of the Galaxy. Sorry, but the gist of the post seems to smack a little bit of some "religious" agenda...I certainly hope that isn't the case, here.

Sometimes, some folks seem to get it "backwards"....thinking that ONLY the Earth and its environment is possible for life-as-we-know-it to exist.

They forget that it works the other way: WE are here, not because the Earth is "perfect" for us...WE are "perfect" for it!!!

Change the conditions on this planet, going back millions or billions of years, and the end result types of species that may then be produced, if conditions warrant, WOULD be very different from what we know...( and "they" might possibly then be making the same incorrect assumptions about themselves, and "their" existence, too! ).





[edit on 26 August 2010 by weedwhacker]

I remember reading an article stating that a planet just like ours was discovered in some remote galaxy (could be even our own) that contains water and is close enough to it's sun to sustain life.


Now, if there are some differences, I am sure that life on that planet could ADAPT to the different conditions. If radiation there is higher, for example, than life simply has higher tolerance of radiation and so forth

Originally posted by weedwhacker
reply to post by Calender

 

Well....(not peeing all over your work, just quibbling with some of the more blatant assumptions. SOME things you mention are not up for argument, though. Like, the fact that WE are here, and our planet is fairly stable, because of our fortuitous Moon...but, it isn't as simple as all that, either...).


Early on, in just the opening post, I had a great deal of difficulty with this:

Firstly, our solar system is in an ideal spot in the Milky Way Galaxy.

??? Come on! No way to make a statement that absolute, because we KNOW LITTLE about the Galaxy!!

There is still much to explore, and discover. Our distance and remoteness? Nice, and useful for us..but there's a LOT of Galaxy too...

You did not negate what science has discovered. We indeed live in "prime real estate" in the galaxy. This is not a spurious statement. If you were to go much closer to the center of the galaxy harmful raidation would not allow life to exist on the planet earth. And further out the heavier elements needed to sustain life do not exist.

This is according to Scientific American, Special Issue 2008 entitled "Majestic Universe". You can specifically look up page 11.

There are many other scientific works that testify to this statement. Do you have any other arguments?

Originally posted by frozenspark
I remember reading an article stating that a planet just like ours was discovered in some remote galaxy (could be even our own) that contains water and is close enough to it's sun to sustain life.


Now, if there are some differences, I am sure that life on that planet could ADAPT to the different conditions. If radiation there is higher, for example, than life simply has higher tolerance of radiation and so forth

There is no remotely possible way that planets could have been discovered in remote galaxies. They are much too distant to have observed planets.

Do you have a reference to this claim?

reply to post by Calender


I think this may be it, though I read it on CNN

www.dailymail.co.uk...

it was so long that I read this article, it is very possible that it is not some remote galaxy but our own Milky Way. But the point remains, there are planets out there that have conditions that could sustain life.

reply to post by frozenspark

You remember wrong. Smallest discovered exoplanet thus far has about 4 times the mass of Earth and is 60 times closer to its star.

reply to post by Calender


I get what you're saying, and I do like to read SA...

...but, think about it. We are in the "backwaters" of ONE of the spiral arms (we really don't know for sure the EXACT shape of this Galaxy, we have to guess a bit, and compare to others that we can see, from afar...so, observations seem to point to the "spiral" shape...still, we ARE observing from within. It's like, trying to figure out what your house looks like, but you can't leave it to look back at it....you can see the houses across the street, though....).

However, there ARE other 'arms', and locations of equi-distance from the center (wehre, yes...conditions likely are NOT conducive for our carbon-based fragile lifeforms' benefit).

PLUS, you forget to think in three dimensions, too. Space is VAST.....









[edit on 26 August 2010 by weedwhacker]

Originally posted by frozenspark
reply to post by Calender

 

I think this may be it, though I read it on CNN

www.dailymail.co.uk...

it was so long that I read this article, it is very possible that it is not some remote galaxy but our own Milky Way. But the point remains, there are planets out there that have conditions that could sustain life.

Thank you for the link. I remember reading this article awhile back. Yea, it's in our own neighborhood, only 20 light years away.

If you read the statistic of the star though, it is much different than ours. The star is a different color, a third of the size of our sun, 50 times cooler than the sun, and if you notice a huge planet circles the inner planetary system, as was mentioned in the post above. That planet alone would make the stability of the orbit of the outer one much to questionable to sustain life.

Originally posted by weedwhacker
reply to post by Calender

 

I get what you're saying, and I do like to read SA...

...but, think about it. We are in the "backwaters" of ONE of the spiral arms (we really don't know for sure the EXACT shape of this Galaxy, we have to guess a bit, and compare to others that we can see, from afar...so, observations seem to point to the "spiral" shape...still, we ARE observing from within. It's like, trying to figure out what your house looks like, but you can't leave it to look back at it....you can see the houses across the street, though....).

However, there ARE other 'arms', and locations of equi-distance from the center (wehre, yes...conditions likely are NOT conducive for our carbon-based fragile lifeforms' benefit).

PLUS, you forget to think in three dimensions, too. Space is VAST.....

[edit on 26 August 2010 by weedwhacker]

I am aware of this. I would like to add I am not saying there are not other planets out there like our own. I don't know, and do not claim to know.

My point is so far our solar system has been shown to be quite unique.

Also, if you are looking for life out there, shouldn't you take into account these factors, and not just randomly look for it everywhere?

Nice work. S&F.

I wish more people would appreciate the uniqueness of the planet we live on. If more people did, perhaps our home would not be such a mess.

Thanks for your message!

Here is a movie that goes along with your post. I hope you enjoy it.




[edit on 26-8-2010 by ByteChanger]

I agree with probably 98% of weedwhacker's posts, but I think this thread may fall into the 2% where he is a little harsher than I would be about the discrepancies in the OP. First, I had to look up the definition of the word "unique" and of the two main definitions, it makes a great deal of difference which one you use.

unique

I think Weedwhacker is using the "sole" definition while maybe Calender is using the "unusual" definition. Obviously there is no way to support the first definition so we (the people who aren't some kind of religious zealot) must be talking about the second one.

I have often considered many of these same factors myself and it is for this reason I think many estimates for factors in the Drake equation look a little on the large side to me, and some of these factors may warrant somewhat lower estimates. Even when you use some extreme estimates like Carl Sagan did in the Series Cosmos, he still came up with 10 intelligent species in the Milky way, clearly these 10 intelligences would be unique in the "unusual" sense but not unique in the "sole" sense.

Having said I agree with many of your statements, I will just pick out 2 things where I don't agree, one is really a correction and the other is a biased conclusion:

Originally posted by Calender
One is the nearly circular orbit that our planets have around our central star, the sun. Almost all exo-planetary systems have very ecliptic orbits, not circular at all.

I think the word you are looking for here, is eccentric, not ecliptic? Ecliptic is related to the 23 degree tilt of the Earth's axis relative to its orbit around the sun:

ecliptic

Two, is the position of our planets in the solar system seems to be unique. Not only are all of the orbits circular but the larger planets are in the outer solar system. Again almost uniformly all exoplanetary system discovered to date have huge planets in the inner solar system.

Your data may be correct, but the conclusions you are drawing from it may be unfounded and incorrect. The reason we find large exoplanets close to their stars is because they are the easiest objects to find. How long do you think scientists have had the technology to detect a planet like our earth orbiting a star like our sun?

en.wikipedia.org...

NASA's Kepler mission was launched on March 6, 2009. Unlike previous searches, it is sensitive to planets as small as Earth, and with orbital periods as long as a year.

Not very long and it probably takes something like three years to make the first conclusive discoveries, of earth type planets/orbits, so it hasn't even been that long. I expect to hear some interesting discoveries announced in 2012-2016 resulting from the Kepler mission but the mission is still in its infancy now.

The reason we are finding what we are finding is because what we are finding is relatively easy to find. That doesn't mean it's a representative sample of what's out there.

note that most of the observed planets have very eccentric orbits, or orbit very close to the sun where the temperature is too high for earth-like life. However, several planetary systems that look more solar-system-like are known, such as HD 70642, HD 154345, or Gliese 849. These may well have smaller, as yet unseen, earth-sized planets in their habitable zones.

Just a few comments on some of your other ideas:

I've read the theories that Earth's rotation may be unstable without the influence of the moon, but I'm not entirely sure about the top-spinning analogy, but I think the most important part of the moon's creation is the spinning of the Earth, so one side doesn't bake as you said. However I don't think the spin rate is super-critical. For example would it be a problem if the Earth spun twice as fast, of half as fast? In fact the spin rate of the Earth as well as the distance of the moon from the Earth changes over time so they are not fixed parameters. Thank goodness a day isn't 12 hours long though, sometimes 24 hours doesn't seem long enough. But I don't think spinning is all that unique.

www.spacedaily.com...

the terrestrial day was only about five hours long when the Moon first formed close to the Earth.

(that's a guess based on models but we know the days were shorter even if that amount is an estimate instead of an exact value)

I would also like to say while the Earth's magnetic shield is a nice thing to have, Earth's magnetic field isn't that strong and neither is our radiation shield, and it varies over time, even reverses polarity. It's probably not strong enough, for example, to make an effective shield against the X-ray radiation of the most common type of stars, red dwarfs:

Living with a Red Dwarf

Roughly three quarters of the stars in the galaxy are red dwarfs...life might not be a picnic around a red dwarf. Several times per day flares shoot off the star, causing the UV radiation to jump by 100 to 10,000 times normal...This increased radiation could sterilize the surface of a nearby planet.Even between flares, the combination of UV light and stellar winds can strip away the atmosphere if nothing is protecting or replenishing it.
As they age, red dwarfs become less magnetically active, while continuing to shine steadily at visible wavelengths for 100 billion years or more. Therefore, if an orbiting planet can just hold onto its atmosphere through the wild early years of its red dwarf roommate, it could end up being a decent place to live.

Actually they can also emit intense X-ray emissions in addition to the UV radiation and Earth's protection would just be totally inadequate. However I suppose it's possible or even probable that other planets have stronger magnetic fields than earth's, but whether the atmosphere and life could survive the radiation bombardment from even a stronger magnetic shield is questionable at best.

Earth hasn't always been the relative Paradise it's been for the last 10,000 years or so. A little bit before that, maybe 13000 years ago there was an extinction of the clovis people in North America, and of course at least 5 mass extinctions like the one that wiped out the dinosaurs.

I would also note that the environment here seems ideal for us because, well, we evolved in an adaptation to live in it. I wouldn't find it odd if organisms that evolved on Jupiter find the conditions on Jupiter ideal, because, they evolved to live in those conditions. I'm not saying I think life on Jupiter is likely, but it may not be impossible and if there is life there or on a Jupiter-like planet elsewhere, such life may have a different idea of ideal conditions than we do.

[edit on 27-8-2010 by Arbitrageur]

Life exists on various levels, and it evolves according to his surroundings. So it is not by accident that our planet happens to be exactly right for us, but rather we adjusted with the planet.

This is funny... Cause I JUST read an artical on a science news website about one of the space probes searching for exo-planets.... It said they have looked at over 156,000 stars and not found to many planets that can be considered earth like. Most planets are yes very large and full of danger, like saturn and jupitor...

Our planet is EXTREMELY RARE! No matter what you think you know it's true. Clusters of stars may have radiation beyond what life as we know it can handle but there could be other life forms out there that are tolerant so I wouldn't exclude that fact of harmful radiation but thats only based off life as WE know it.

Also, weedwacker... You're kind of rude about your statements don't disregard useful information based off what you think you might know. Our moon is extremely vital to our solar system in general. Without it you could've possibly not even be here, in-fact probably wouldn't be here. Human life would have had a chance of not being here.

I'd also like to say that we are at a very good location in the universe not just our galexy... One more thing about the Earth is that it probably didn't sustain life some billions of years ago until it was struck by an aseroid containing the Iron that made our Electromagnetic field and water the essence of life.