The violent youth of solar proxies. Courtesy of IAU.

Sun, Earth Are Unlikely Pair to Support Life

Article Updated: 24 Dec , 2015

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We don’t know how lucky we are — really.

We know the interaction between Earth and Sun is a rarity in that it allowed life to form. But scientists working to understand the possibility that it could have happened elsewhere in the Universe are still far from drawing conclusions.

What is becoming clearer is that life probably shouldn’t have formed here; the Earth and Sun are unlikely hosts.
A series of presentations at this year’s meeting of the International Astronomical Union meeting, in Brazil last week, focused on the role of the Sun and Sun-like stars in the formation of life on planets like Earth.

Edward Guinan, a professor of astronomy and astrophysics at Villanova University in Pennsylvania, and his collaegues have been studying Sun-like stars as windows into the origin of life on Earth, and as indicators of how likely life is elsewhere in the cosmos. The work has revealed that the Sun rotated more than ten times faster in its youth (over four billion years ago) than today. The faster a star rotates, the harder the magnetic dynamo at its core works, generating a stronger magnetic field, so the young Sun emitted X-rays and ultraviolet radiation up to several hundred times stronger than it does today.

A team led by Jean-Mathias Grießmeier from ASTRON in the Netherlands looked at another type of magnetic fields — that around planets. They found that the presence of planetary magnetic fields plays a major role in determining the potential for life on other planets as they can protect against the effects of both stellar particle onslaughts.

“Planetary magnetic fields are important for two reasons: they protect the planet against the incoming charged particles, thus preventing the planetary atmosphere from being blown away, and also act as a shield against high energy cosmic rays,” Grießmeier said. “The lack of an intrinsic magnetic field may be the reason why today Mars does not have an atmosphere.”

All things considered, the Sun does not seem like the perfect star for a system where life might arise, added Guinan.

“Although it is hard to argue with the Sun’s ‘success’ as it so far is the only star known to host a planet with life, our studies indicate that the ideal stars to support planets suitable for life for tens of billions of years may be a smaller slower burning ‘orange dwarf’ with a longer lifetime than the Sun — about 20-40 billion years,” he said.

Such stars, also called K stars, “are stable stars with a habitable zone that remains in the same place for tens of billions of years,” he added. “They are 10 times more numerous than the Sun, and may provide the best potential habitat for life in the long run.”

Not are planets like Earth the best places to harbor life, he said. Planets double or triple the size of Earth would do a better job of hanging onto an atmosphere and maintaining a magnetic field: “Furthermore, a larger planet cools more slowly and maintains its magnetic protection.”

Manfred Cuntz, an associate professor of physics at the University of Texas at Arlington, and his collaborators have examined both the damaging and the favorable effects of ultraviolet radiation from stars on DNA molecules. This allows them to study the effect on other potential carbon-based extraterrestrial life forms in the habitable zones around other stars. Cuntz says: “The most significant damage associated with ultraviolet light occurs from UV-C, which is produced in enormous quantities in the photosphere of hotter F-type stars and further out, in the chromospheres, of cooler orange K-type and red M-type stars. Our Sun is an intermediate, yellow G-type star. The ultraviolet and cosmic ray environment around a star may very well have ‘chosen’ what type of life could arise around it.”

Rocco Mancinelli, an astrobiologist with the Search for Extraterrestrial Life (SETI) Institute in California, observes that as life arose on Earth at least 3.5 billion years ago, it must have withstood a barrage of intense solar ultraviolet radiation for a billion years before the oxygen released by these life forms formed the protective ozone layer. Mancinelli studies DNA to delve into some of the ultraviolet protection strategies that evolved in early life forms and still persist in a recognizable form today. As any life in other planetary systems must also contend with radiation from their host stars, these methods for repairing and protecting organisms from ultraviolet damage serve as models for life beyond Earth. Mancinelli says “We also see ultraviolet radiation as a kind of selection mechanism. All three domains of life that exist today have common ultraviolet protection strategies such as a DNA repair mechanism and sheltering in water or in rocks. Those that did not were likely wiped out early on.”

The scientists agree that we do yet know how ubiquitous or how fragile life is, but as Guinan concludes: “The Earth’s period of habitability is nearly over — on a cosmological timescale. In a half to one billion years the Sun will start to be too luminous and warm for water to exist in liquid form on Earth, leading to a runaway greenhouse effect in less than 2 billion years.”

Why is the Sun yellow?

Source: International Astronomical Union (IAU). A link to the meeting is here.


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tacitus
Member
August 10, 2009 4:25 PM

No doubt the “rare-earthers” (i.e. creationists) will be touting this research as confirmation of how “special” Earth is as a harbor for life. But as Torbjorn says, a proper reading of the findings is actually more encouraging, not less, given the abundance of orange dwarfs in the galaxy.

Of course there are orders of magnitude more red dwarf stars that orange dwarfs, and they are stable for tens of billions of years. They have their own challenges regarding being places where life can form (many of them are flare stars) but given their numbers, we certainly can’t rule them out as yet either.

tomkaten
Member
tomkaten
August 10, 2009 1:27 PM

I thought the probability of finding a life-harboring planet orbiting a brown dwarf is smaller, since the habitable zone is much closer to this kind of star and being close to your host star is never a good thing.

Planets that are that close might become tidally locked and permanently expose one side to the host star, with devastating effects on the planet’s climate. Not to mention the increased star wind and radiation inherent to such small distances.

Sure, it’s nice to be able to include smaller and ultra stable stars into equation, while boosting the odds of life appearing in the process, but I don’t think that the expected life span of a star tells the whole story here.

Jon Hanford
Member
Jon Hanford
August 10, 2009 1:52 PM

Missed the presentation on the ‘electric comet’ theory. Those modern astronomers are surely delusional on this proven fact smile

Torbjorn Larsson OM
Member
Torbjorn Larsson OM
August 10, 2009 3:46 PM
tomkaten, I suspect that you mean red dwarfs (M type, I believe) and I suspect your concerns is why they discuss orange dwarfs (K type). Also, I suspect that the article describes planets regardless of habitable zone, since we don’t know that life is rare. Rather the IAU talks seems to suggest the reverse, i.e. if life could get hold in a tempestuous environment it could easily get hold in more calm ones. “”The Earth’s period of habitability is nearly over — on a cosmological timescale.” OTOH, on its own scale of habitability it will continue for at least 10 % of its lifetime, or possibly up to 40 %. I tend to think the later is favored,… Read more »
Anaconda
Member
Anaconda
August 10, 2009 5:33 PM

@ Jon Hanford:

“Missed the presentation on the ‘electric comet’ theory. Those modern astronomers are surely delusional on this proven fact smile

Well…since your asked:

http://thunderbolts.info/pdf/ElectricComet.pdf

Now, the underlying basis for the “electric” comet theory is that there is an ‘electric field’ that accompanies the solar wind, and how would we know that?

Easy, the solar wind’s charged particles accelerate past the Earth and what else would accelerate the charged particles besides an ‘electric field’ which is undisputedly known to accelerate charged particles.

The ball is in your court, Jon smile

Jon Hanford
Member
Jon Hanford
August 10, 2009 8:19 PM

So now you’re telling us that ‘all’ comets are electromagnetic phenomena but that they cannot be a low-density object in our solar system or a soot-covered body of icy molecules? Meaningful citations, please smile

Ivan3man_At_Large
Member
Ivan3man_At_Large
August 11, 2009 1:17 AM

@ Anaconda,

By “meaningful citations”, Jon Hanford means from independent, peer-reviewed sources, not from that Thunder[bollocks].info outfit, which is to science what the Ku Klux Klan is to civil rights.

The Eclectic Exterminator of Stupid Electricians
Member
The Eclectic Exterminator of Stupid Electricians
August 11, 2009 2:12 AM

@ Anaconda
Enough of you acting like a jackass. No one believes you stupid personal theories, and frankly no one is really interested in your fringe personal idiotic ideas.
My advice to you is to just go away. Nobody is interested anymore.
As for quoting from the fraudulent and deceptive Thunderdolts.Info site – everyone already they are liars and deluded fools.
Now go away you totally pathetic fool!

Nexus
Member
August 11, 2009 2:26 AM

Yes, the electric universe theory is a lot of twaddle and crackpot nonsense but I don’t think there’s any call for those kinds of personal attacks.

Jon Hanford
Member
Jon Hanford
August 11, 2009 4:38 AM

“Missed the presentation on the ‘electric comet’ theory.” Actually, I still missed a peer-reviewed, published paper giving a complete EU description of comets?

“Well…since your asked:”…..No. I didn’t ask (reread my post!) and if I did, it sure wouldn’t be from Anaconda.

In Anaconda’s post he mentions “what else would accelerate the charged particles besides an ‘electric field’ which is undisputedly known to accelerate charged particles.” Wouldn’t a nuclear bomb or a supernova accelerate charged particles sans an EM field?

Dark Gnat
Member
Dark Gnat
August 11, 2009 6:52 AM

I think this does show how precious this planet and the life it holds really is.

This is our only home. There is nohing else out there that is within reach.
Being “green” is all the rage these days, though I think it has more to do with appearances than actual conservationism.

If we really want to make a difference, we need to stop all deforestation, especially in the tropics.

EU controversy: Until EU = pseudoscience. So what if the big bang was discovered by a Christian? Guess what, the guy that discovered genetics was a Christian too, (and a priest) should we wipe that away?

Leave your political anti-religion/anti-science ideas at the door.

ND
Member
ND
August 11, 2009 7:45 AM

IVAN3MAN,

The KKK comparison was a bit harsh, no?

SteveZodiac
Member
SteveZodiac
August 11, 2009 8:35 AM

It does seem that we exist only because of several coincident factors, the Earth’s core makeup and its generation of a magnetic field, the moon’s stabilisation of the earth’s axis, tectonic plates, cometary impact water, the list keeps getting longer, If there is a creator of the cosmos then we must be its accident child. Perhaps that’s why nobody “out there” has come to visit us..

DrFlimmer
Member
DrFlimmer
August 11, 2009 9:55 AM

Gee…….

Btw: The earth is special. I don’t think that there is a planet anywhere in space that exactly is like the earth. Most likely there is life somewhere else – but will it look like life on earth? Will that planet look like the earth?

And I second SteveZodiac, yes, many factors came together….

Ivan3man_At_Large
Member
Ivan3man_At_Large
August 11, 2009 10:00 AM

@ ND,

I was never one to mince my words; I tell it like it is! wink

Dark Gnat
Member
Dark Gnat
August 11, 2009 10:06 AM

If God does exist and is the Creator, there is no reason why he would limit life to one world. ET life should be compatible with Christian religion,as Angels would technically be aliens, anyway.

A planet with a different chemical makeup, which orbits a different star type might yield life with vastly different bio-chemestry. Aliens on that planet may be searching for life that’s similar to them, because that’s the only model they have. We do the same thing.

How would a blind man and a deaf man who speak different languages communicate if they were miles from each other, especially without compatible technology?

ND
Member
ND
August 11, 2009 10:14 AM

IVAN3MAN, yes you do! smile

“Interviewer: Well, can you… blow up the world?
Tick: Egad. I hope not. That’s where I keep all my stuff. “

Anaconda
Member
Anaconda
August 11, 2009 10:36 AM
The personal attacks reflect more on the character of people making the attacks than on the person who is at the receiving end of the attacks. Personal attacks certainly don’t suggest an open-mind regarding the scientfic evidence. “Ridicule is man’s most potent weapon.” –Saul Alinsky, commited American Socialist. Jon Hanford wrote: “…but that they [comets] cannot be a low-density object in our solar system or a soot-covered body of icy molecules? Meaningful citations, please ” It’s possible, but that conclusion is based on assumptions that sublimation of ice into gasses causes the ‘coma’ and ‘tail’ of comets, but there is an alternative explanation that at the present time fits the observations & measurements better. Meaningful citations? I’ve linked… Read more »
Manu
Member
Manu
August 11, 2009 10:45 AM

Funny, I had always believed Lemaitre *calculated* a valid solution to Einstein’s general relativity equations. Also arrived at by Friedmann, incidentally.

Nereid
Member
Nereid
August 11, 2009 10:48 AM
In case anyone missed it … Anaconda posted a link to the infamous Thornhill “poster” in another UT story thread. I responded as follows (typo fixed): – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – Anaconda introduces the infamous Thornhill poster. I spent some time going through it, and posted my results in a thread, started by a self-admitted proponent of EU ideas, in BAUTForum, entitled “New research results from the “Stardust” mission”^. From one of those posts: Are Thornhill and Talbott being (intellectually) dishonest? Is there something fraudulent about the… Read more »
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