The Purple Earth hypothesis is an astrobiological hypothesis that life forms of early Earth were retinal-based rather than chlorophyll-based thus making Earth appear purple rather than green. An example of a retinal-based organism today is the photosynthetic microbes called halobacteria.
Two difficulties with the hypothesis lie in halobacterial metabolism. While it is true that halobacteria can photosynthesize anaerobically, they require arginine to do so. As a complex amino acid, arginine is not likely to have been available in the levels needed. Second, the retinal of the photosynthetic purple membranes requires oxygen for its synthesis. Oxygen is made available by chlorophyll-based photosynthesis, so the halobacteria cannot be the precursors to it.
Video Purple Earth hypothesis
See also
- Red edge
Maps Purple Earth hypothesis
References
External links
- Colorful Worlds: Plants on Other Planets Might Not Be Green
- [1] 2007 AAS/AAPT Joint Meeting, American Astronomical Society Meeting 209, #06.05; Bulletin of the American Astronomical Society, Vol. 38, p. 901
- [2] BR Green, E Gantt - J Phycol, 2000 - interscience.wiley.com
- [3] Softpedia article
- [4] Fox News article
Source of the article : Wikipedia
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