Life May Have Formed on Earth Thanks to a Lush, Enveloping Haze

By Joseph Calamia | June 3, 2010 5:31 pm

titanYou can’t rise from the primordial ooze if that ooze is frozen. But about three billion years ago the sun was around thirty percent dimmer, meaning our planet should have been a snowball. The puzzle has haunted scientists for decades, but a study in Science has a new answer: It argues that a dense cloud of “fractal haze” enveloped the Earth.

Old Theories

This isn’t the first attempt to solve the early Earth conundrum. Carl Sagan, for one, had a few ideas. First, in 1972, he speculated that the atmosphere had ammonia which could trap heat, but later work showed that the sun’s ultraviolet radiation would have broken that ammonia down. In 1996 he tried again, saying that Earth might have had a thick haze, perhaps a nitrogen-methane mix, that blocked the ultraviolet but let in enough of the sun’s then-meager rays to warm the planet. Unfortunately, that too was a no go:

Early models assumed the haze particles were spheres, and that when individual particles collided, they globbed together to make bigger spheres. These spheres blocked visible light as well as ultraviolet light, and left the Earth’s surface even colder. “It basically led us to a dead end where we couldn’t have a warm early Earth,” said Eric Wolf, a graduate student in atmospheric sciences at the University of Colorado at Boulder and the first author of the new study. [Wired]

This Theory

The perfect haze was not too sparse (since it needed to provide some UV-protection for developing life), and not too dense (because then the planet would have been dark and cold). Just right, the new study suspects, might have been hydro-carbon clouds of what the study’s authors call fractal haze. Unlike the spherical haze particles, fractal haze is made of long chains of particles stuck together.

The end result of this arrangement, dubbed a fractal size distribution, would be an aerosol haze opaque enough to block the shortwave ultraviolet radiation that would have hindered or prevented life from arising. At the same time, it would have proven transparent enough in longer, visible wavelengths to let them keep the atmosphere warm and the planet wet enough for life to emerge. “It’s surprising that molecules with complex shapes could make such a difference,” said researcher Eric Wolf []

This theory also allows Sagan’s ammonia, protected from the UV, to exist in the atmosphere. The famous Miller-Urey experiment–in which scientists sparked what they believed comprised the earth’s early atmosphere and made amino acids, life’s building blocks–assumed that the young planet had ammonia to work with.

Alternate Theories?

But in April, scientists proposed another answer: that the young earth had smaller land masses and so reflected fewer of the sun’s rays, absorbing more heat. But it’s possible that the theories can work together.

Rather than being an alternate explanation to last month’s theory about how Earth stayed warm under a faint young sun, the newly proposed haze layer may actually be a complement to it, says Wolf. Researchers who conducted that study didn’t include a haze layer, which probably would have helped keep their darker world warm enough to prevent water at Earth’s surface from freezing. Future research could clarify the issue, Wolf notes. [Science News]

This all means that Earth’s baby picture probably looked a lot like a current shot of Saturn’s moon Titan (shown above).

Related content:
80beats: Our Alien Atmosphere? Earth’s Gases May Have Arrived Here Aboard Comets
Bad Astronomy: When did Earth’s Oxygen atmosphere appear?
Bad Astronomy: Titan’s shadow

Image Credit: NASA/JPL/Space Science Institute

  • toomuch

    if you all would remember that there is an almighty CREATOR you would not keep asking yourselves these questions. Yes there was a haze over the earth and then GOD said “let there be light” yes i am so sorry, but it is simply that simple. The reason it all works so well is because it is all controlled by an Almighty GOD that for some reason still loves the inhabitants of this planet. Even though we continue to kill it off day by day and even though many continue to believe it all just appeared out of the haze. Well you all may be a little dazed from the haze(or whatever you are smoking)but the final undisputablie answer is this. GOD created it all and GOD makes sure that it all works the way it should. You may say I am naive, but I am actually just a die hard believer in GOD and HE loves you too even in your arrogant ignorance thinking you can figure out the mind of GOD. What you should be doing is saying why hasn’t HE just finished it, because HE loves us that much and this is HIS most excellant work and HE is not ready to put an end to it. Whether it be 2012 of 3012 GOD is in control. So give yourself a break and just say it, GOD created it to be the way it needed to be so we could survive. Why? Because HE is a big GOD and there is more going on than you understand until you read HIS book.

  • BadWolf

    I think it’s really cool that you believe so strongly in god, and it’s great and all, but you shouldn’t push your own beliefs on others. I don’t believe in god, since i’ve seen no proof or anything, and i can’t imagine that there’s something else bigger than the universe, but I don’t care what you believe. You can believe what you want, and I can believe what I want. It’s perfectly fine for some people to not believe in god; they aren’t hurting you or anything, and if you believe that they’ll go to hell or something for not believing in god, then it’s only hurting them, but obviously they don’t mind because they don’t believe in god. It’s not that we’re ignorant or arrogant (actually, I think quite a few die hard believers in god are arrogant, since they believe they are right and everyone who doesn’t believe in god is wrong), we just believe in something else.

  • Jamal

    @ toomuch

    I don’t believe in God because as a theory it doesn’t really explain anything and just replaces one mystery with a bigger mystery (if God created the universe then who or what created God?) Also, even if there was a God, I don’t see any logical reason why we should associate him/her/it with any particular deity from any particular religion or mythology, given that there is absolutely zero evidence for doing so.

    However, having said all that, I agree that the seemingly fine-tuned nature of the universe (both on a cosmological and biological scale) towards the emergence of life is something that can’t be ignored. I have my own personal theory, which I won’t go into here, but I recommend the book “The Goldilocks Enigma” by Paul Davies as a balanced overview of the relevant issues.

  • messengers download

    hank you for the helpful tips! I might not need gotten this by myself! Could it be alright to reference things about this on my website if I add a backlink for this webpage?


Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!


80beats is DISCOVER's news aggregator, weaving together the choicest tidbits from the best articles covering the day's most compelling topics.

See More

Collapse bottom bar