Related Experiment Video
Updated: Jun 12, 2026
11:28
Isolating and Incorporating Light-Harvesting Antennas from Diatom Cyclotella Meneghiniana in Liposomes with Thylakoid Lipids
Published on: August 28, 2018
Fractal organic hazes provided an ultraviolet shield for early Earth
1Department of Atmospheric and Oceanic Sciences, Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80309-0311, USA.
Science (New York, N.Y.)
|June 5, 2010
Summary
Archean Earth likely had a hydrocarbon haze that shielded it from ultraviolet radiation. This fractal haze was thick in UV light but transparent to visible light, preventing significant cooling.
Area of Science:
- Geoscience
- Atmospheric Science
- Astrobiology
Background:
- The Archean Eon (3.8 to 2.5 billion years ago) featured a unique atmosphere.
- Photochemical hazes, composed of hydrocarbon aerosols, are hypothesized to have existed.
- The fractal structure of these aerosols could significantly impact atmospheric radiative properties.
Purpose of the Study:
- To investigate the radiative properties of fractal aggregate hydrocarbon hazes.
- To determine the potential shielding effects of such hazes on early Earth.
- To assess the impact of haze on early Earth's climate.
Main Methods:
- Radiative transfer modeling of fractal aggregate haze.
- Analysis of optical thickness in ultraviolet and visible wavelengths.
- Estimation of haze impact on planetary temperature.
Main Results:
- The fractal aggregate haze was optically thick in ultraviolet (UV) wavelengths.
- The haze remained relatively transparent in the mid-visible wavelengths.
- A haze production rate of 10(14) g/year with 50 nm monomer radius offered strong UV shielding.
Conclusions:
- Archean photochemical haze provided significant protection from harmful UV radiation.
- The haze caused minimal antigreenhouse cooling, suggesting a limited impact on global temperature.
- These findings have implications for the habitability of early Earth and the search for life on exoplanets.
Related Concept Videos
02:06Conditions on Early Earth
Around 4 billion years ago, oceans began to condense on earth while volcanic eruptions released nitrogen, carbon dioxide, methane, ammonia, and hydrogen into the primordial atmosphere. However, organisms with the characteristics of life were not initially present on earth. Scientists have used experimentation to determine how organisms evolved that could grow, reproduce, and maintain an internal environment.
02:06Conditions on Early Earth
Around 4 billion years ago, oceans began to condense on earth while volcanic eruptions released nitrogen, carbon dioxide, methane, ammonia, and hydrogen into the primordial atmosphere. However, organisms with the characteristics of life were not initially present on earth. Scientists have used experimentation to determine how organisms evolved that could grow, reproduce, and maintain an internal environment.
01:26Origin of Photosynthesis
Photosynthesis represents a fundamental biological process that transformed Earth's atmosphere and paved the way for complex life. Emerging roughly 3.4–3.8 billion years ago, the earliest photosynthetic organisms harnessed light energy to produce organic compounds. These anoxygenic phototrophs used electron donors like hydrogen sulfide (H₂S) or ferrous iron (Fe²⁺), rather than water, and did not release molecular oxygen (O₂) as a byproduct. Various groups, including green sulfur and purple...
01:24Origin of Cellular Life
The origin of life on Earth is a complex and enigmatic event rooted in ancient biochemical processes and geological conditions. Experimental evidence supports the hypothesis that life began with the spontaneous formation of organic molecules such as RNA nucleotides, amino acids, and lipids under early Earth conditions. Factors like volcanic activity, intense UV radiation, and a reducing atmosphere without free oxygen likely facilitated these reactions. Hydrothermal vents on the ocean floor are...
02:35What is Evolutionary History?
Scientists record evolutionary history by analyzing fossil, morphological, and genetic data. The fossil record documents the history of life on Earth and provides evidence for evolution. However, both fossil and living organisms offer evidence that outlines Earth’s evolutionary history.Phylogenetic trees illustrate the evolutionary relationships among these organisms. Scientists infer organisms’ common ancestry by evaluating shared morphological and genetic characteristics. Together, the fossil...
02:56The Fossil Record
The fossil record documents only a small fraction of all organisms that have ever inhabited Earth. Fossilization is a rare process, and most organisms never become fossils. Moreover, the fossil record only exhibits fossils that have been discovered. Nevertheless, sedimentary rock fossils of long-lived, abundant, hard-bodied organisms dominate the fossil record. These fossils offer valuable information, such as an organism's physical form, behavior, and age. Studying the fossil record helps...