Author Topic: Alien Planet 'Super-Earth' Called Best Candidate To Support Life  (Read 10117 times)

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Offline Yla

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Re: Alien Planet 'Super-Earth' Called Best Candidate To Support Life
« Reply #15 on: February 03, 2012, 06:17:04 am »
Given that the habitable zone of a star constantly moves chances are that far more planets can be found where water is liquid. Of course, solar events can cause a planet to shift in its orbit resulting in a planet that was perhaps too close being dragged further out in into the habitable zone.
What kind of solar event would change the planetary orbit and not blow the planet to bits with it?
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Offline Sylvana

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Re: Alien Planet 'Super-Earth' Called Best Candidate To Support Life
« Reply #16 on: February 03, 2012, 06:49:12 am »
Given that the habitable zone of a star constantly moves chances are that far more planets can be found where water is liquid. Of course, solar events can cause a planet to shift in its orbit resulting in a planet that was perhaps too close being dragged further out in into the habitable zone.
What kind of solar event would change the planetary orbit and not blow the planet to bits with it?

Well the late formation of a planet like Jupiter would. The obits of all the inner planets were much closer to the sun before Jupiter formed from the outer solar system dust. This event was also responsible for the heavy late bombardment.

Offline Askold

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Re: Alien Planet 'Super-Earth' Called Best Candidate To Support Life
« Reply #17 on: February 03, 2012, 08:22:10 am »
Given that the habitable zone of a star constantly moves chances are that far more planets can be found where water is liquid. Of course, solar events can cause a planet to shift in its orbit resulting in a planet that was perhaps too close being dragged further out in into the habitable zone.
What kind of solar event would change the planetary orbit and not blow the planet to bits with it?

Well the late formation of a planet like Jupiter would. The obits of all the inner planets were much closer to the sun before Jupiter formed from the outer solar system dust. This event was also responsible for the heavy late bombardment.

Impact with a large asteroid or another planet would also do the trick and would not necessarily reduce the planet to bits. (The surface of the planet though would probably go through a quick and violent make over.)
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Offline Sigmaleph

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Re: Alien Planet 'Super-Earth' Called Best Candidate To Support Life
« Reply #18 on: February 03, 2012, 11:20:09 am »
Given that the habitable zone of a star constantly moves chances are that far more planets can be found where water is liquid. Of course, solar events can cause a planet to shift in its orbit resulting in a planet that was perhaps too close being dragged further out in into the habitable zone. On a planet like this it would be the ideal temperature for water to be liquid, but because of the water being boiled away earlier in the planets existence there would be no water now.
Question: Wouldn't the water still remain in the planet's atmosphere? And thus become liquid again once the planet reaches the habitable zone?
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Offline Random Gal

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Re: Alien Planet 'Super-Earth' Called Best Candidate To Support Life
« Reply #19 on: February 03, 2012, 01:23:29 pm »
I've never liked the idea that liquid water is essential for life, personally. I think we are putting too many arbitrary limits on what constitutes life by assuming it has to have the same chemical makeup as Earth life.

Offline Vene

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Re: Alien Planet 'Super-Earth' Called Best Candidate To Support Life
« Reply #20 on: February 03, 2012, 03:15:26 pm »
I've never liked the idea that liquid water is essential for life, personally. I think we are putting too many arbitrary limits on what constitutes life by assuming it has to have the same chemical makeup as Earth life.
You'd like this.

The assumption that life requires water, for example, has limited thinking about likely habitats on Mars to those places where liquid water is thought to be present or have once flowed, such as the deep subsurface.  However, according to the committee, liquids such as ammonia or formamide could also work as biosolvents -- liquids that dissolve substances within an organism -- albeit through a different biochemistry.  The recent evidence that liquid water-ammonia mixtures may exist in the interior of Saturn's moon Titan suggests that increased priority be given to a follow-on mission to probe Titan, a locale the committee considers the solar system's most likely home for weird life. 
...
Additionally, studies in chemistry show that an organism could utilize energy from alternative sources, such as through a reaction of sodium hydroxide and hydrochloric acid, meaning that such an organism could have an entirely non-carbon-based metabolism. 

Offline Old Viking

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Re: Alien Planet 'Super-Earth' Called Best Candidate To Support Life
« Reply #21 on: February 03, 2012, 03:17:01 pm »
New Jersey is being closely examined to see if it is habitable by humans.  Preliminary data suggest that the outlook is, at best, poor.
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Re: Alien Planet 'Super-Earth' Called Best Candidate To Support Life
« Reply #22 on: February 03, 2012, 03:18:38 pm »
I've never liked the idea that liquid water is essential for life, personally. I think we are putting too many arbitrary limits on what constitutes life by assuming it has to have the same chemical makeup as Earth life.

It's seems like a good thing to look for though. Water is absurdly common in the universe and we already know how life forms around it (well, sorta).
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Offline Askold

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Re: Alien Planet 'Super-Earth' Called Best Candidate To Support Life
« Reply #23 on: February 03, 2012, 03:47:19 pm »
I've never liked the idea that liquid water is essential for life, personally. I think we are putting too many arbitrary limits on what constitutes life by assuming it has to have the same chemical makeup as Earth life.

We are looking for life similar to what we have on earth because we know what earth lifeforms require to live. There might be planets filled with energy beings or rock-based creatures or intellegent weather patterns but since we don't know what kind of world would support such a life we don't know how to look for it.

Besides there is so much space to search for life so we have to narrow it down somehow. Therefore we look for planets similar to earth and lifesigns similar to those on earth.
No matter what happens, no matter what my last words may end up being, I want everyone to claim that they were:
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Offline Sylvana

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Re: Alien Planet 'Super-Earth' Called Best Candidate To Support Life
« Reply #24 on: February 14, 2012, 05:27:33 am »
Given that the habitable zone of a star constantly moves chances are that far more planets can be found where water is liquid. Of course, solar events can cause a planet to shift in its orbit resulting in a planet that was perhaps too close being dragged further out in into the habitable zone. On a planet like this it would be the ideal temperature for water to be liquid, but because of the water being boiled away earlier in the planets existence there would be no water now.
Question: Wouldn't the water still remain in the planet's atmosphere? And thus become liquid again once the planet reaches the habitable zone?

In the event that a planet is too hot for liquid water you often have the problem of the sun blasting the atmosphere off of a planet, which includes the water that is in that atmosphere. Things like our magnetic field though protect earth from loosing too much atmosphere and if a planet has a similar field it should be reasonably protected. If it then enters the habitable zone, the water should begin to condensate.

Personally I think that is what happened to Mars. There are traces of rivers on mars which would imply running water. As such when the solar system was younger before the formation of Jupiter Mars could have been in the habitable zone and thus had running water. After the orbits shifted mars was pushed out of the zone into its current orbit. Part of the problem is that mars lacks a protective magnetic field and looses an enormous amount of its atmosphere daily, similarly with the high amount of insulating greenhouse gasses in mars' atmosphere causes the planet to be very hot, and thus water would evaporate and then be blasted away with the atmosphere.

With regards to the requirements of life being water, I agree that it is a fairly arbitrary definition. I think we use water as a requirements because it is so plentiful in the universe, while at the same time being a very stable compound. Other liquids should in theory work too, but might be more prone to chemical reactions. I think it will stick as a requirement until we can conclusively find life that is not water or fluid based. As usual, science is working with what we know now, and will fill in the gaps as we go along.

Offline Star Cluster

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Re: Alien Planet 'Super-Earth' Called Best Candidate To Support Life
« Reply #25 on: February 14, 2012, 10:02:14 am »
But then we have Venus, which also has no magnetic field, yet has the densest atmosphere in the solar system.  It is so dense, the pressure at the surface is 92 times greater than Earth.  Venus is only slightly smaller than Earth, has about the same mass and gravity, and is thought to have had oceans at one time.  However, while our atmosphere is mostly nitrogen and oxygen, the Venusian atmosphere is 97% carbon dioxide and 3% nitrogen with a few other trace elements, including water vapor.  This has caused an extensive runaway greenhouse effect which, if there were oceans there, caused them to evaporate.  And it's hot.  Damn hot.  The surface temperature is 460° C (860° F.)  Even if Venus were to move into the habitable zone, there is insufficient water to condense even if the planet were able to cool enough, which is doubtful anyway due to the massive amounts of CO2. 

Mars, on the other hand, is much smaller than Earth.  It's radius is only slightly more than half of Earth's and it's mass is only about 10% of our planet's, making it's gravity much weaker.  If it ever had a dense atmosphere, it is probably for this reason along with the lack of a magnetic field, that it was lost to space. It's atmospheric make-up is quite similar to Venus with carbon dioxide making up 95%, nitrogen 3%, argon 1.5%, with several other trace elements including oxygen and water.  Compare that to Venus and it is almost identical except that Mars' atmosphere is much more tenuous.  The atmospheric pressure at the surface is only about 1% of Earth.  However, it does have seasons much like Earth.  The temperatures range from highs of around -5° C (23° F) in the summers to -87° C (-125° F) in the winter.  The average mean temperature is -63° C (-82° F.)  It has polar ice caps which are probably water ice and it is possible there is a substantial amount of subterranean water.  If Mars were to warm sufficiently to melt the ice caps and bring the underground water to the surface, it is possible that the atmosphere could once more thicken and inject enough oxygen and other essential elements for human survival.  It is even hypothesized that Mars could be purposefully terraformed to support human life. 

Another factor that comes into play is a planet's rotational rate.  Mars has a rotation similar to Earth.  It's day is only slightly longer than Earth's, meaning each side of the planet faces the sun on a regular basis.  Venus, on the other hand, rotates so slowly that it's year is actually longer than it's day.  It takes approximately 225 earth days to orbit the sun, yet it takes 243 earth days to rotate once.  This has contributed to the massive greenhouse effect to the point that the climate is geothermic, meaning temperature doesn't vary from the day side to the night side or from the polar regions to the equator.  (Just as an aside, because I find it interesting, Venus also rotates backwards from most of the other planets.  This is probably due to a massive collision with a large body which literally turned the planet upside down.  And I say most others because Uranus is turned on it's side with one of it's poles pointed towards the sun and basically rolls along it's orbit.) 

All this is to show that there are many factors involved in what can make a planet habitable as we define that condition.  Venus, which is between the habitable zone and the sun, has a runaway greenhouse effect and is extremely hot.  Mars, which is on the other side of the zone, has only a thin atmosphere and is very cold. 

What if their positions had been reversed?  We can speculate that Mars would be like Mercury, the closest planet to the sun.  It has an atmosphere slightly thicker than Mars, and although smaller than Mars, is denser and has more mass, so the gravitational field is about the same.  But then it does have a magnetic field.  Had Mars been on that side of the habitable zone, it would have naturally been much warmer, but whether it could have retained a thicker atmosphere would depend on many factors.  Did it ever have a molten iron core to produce a magnetic field?  If so, would being closer to the sun keep it molten?  Would it's weak gravity have caused it to loose it's atmosphere anyway? 

If Venus were in Mars' position, the atmosphere would probably be cooler, but with it's make-up, would it be cool enough?  Carbon dioxide is a notorious greenhouse gas as we know due to our current experience here in Earth with global warming.  If oceans ever did exist there, the atmosphere could have been much different.  We know that the atmospheric make-up of Earth has changed since its formation, so perhaps the Venusian atmosphere could have supported life as we know it had the planet been in a different location.

I do agree with you and others that the scope of what we consider a habitable environment is narrow, but since the conditions in which we live are the only ones we know, that is to be expected.  That is why I interject the phrase "life as we know it" when talking about the possibility of life elsewhere. Who knows?  We may someday find that life can exist in conditions other than our own.
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