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The Purple Earth Hypothesis (PEH) is an astrobiological hypothesis, first proposed by molecular biologist Shiladitya DasSarma in 2007, [1] that the earliest photosynthetic life forms of Early Earth were based on the simpler molecule retinal rather than the more complex porphyrin -based chlorophyll, making the surface biosphere appear purplish ...
The biological and geological future of Earth can be extrapolated based on the estimated effects of several long-term influences. These include the chemistry at Earth 's surface, the cooling rate of the planet's interior, the gravitational interactions with other objects in the Solar System, and a steady increase in the Sun's luminosity.
In the 18th century, purple was a color worn by royalty, aristocrats and other wealthy people. Good-quality purple fabric was too expensive for ordinary people. The first cobalt violet, the intensely red-violet cobalt arsenate, was highly toxic. Although it persisted in some paint lines into the 20th century, it was displaced by less toxic ...
Purple has long been associated with royalty, originally because Tyrian purple dye—made from the secretions of sea snails—was extremely expensive in antiquity. [1] Purple was the color worn by Roman magistrates; it became the imperial color worn by the rulers of the Byzantine Empire and the Holy Roman Empire, and later by Roman Catholic ...
Fabrics dyed in the current era from different species of sea snail. The colours in this photograph may not represent them precisely. Tyrian purple (Ancient Greek: πορφύρα porphúra; Latin: purpura), also known as royal purple, imperial purple, or imperial dye, is a reddish-purple natural dye.
The value of Earth, i.e. the net worth of our planet, is a debated concept both in terms of the definition of value, as well as the scope of "Earth".Since most of the planet's substance is not available as a resource, "earth" has been equated with the sum of all ecosystem services as evaluated in ecosystem valuation or full-cost accounting.
Porphyry (geology) Porphyry (/ ˈpɔːrfəri / POR-fə-ree) is any of various granites or igneous rocks with coarse-grained crystals such as feldspar or quartz dispersed in a fine-grained silicate -rich, generally aphanitic matrix or groundmass. In its non-geologic, traditional use, the term porphyry usually refers to the purple-red form of ...
As of 2020, the most expensive non- synthetic element by both mass and volume is rhodium. It is followed by caesium, iridium and palladium by mass and iridium, gold and platinum by volume. Carbon in the form of diamond can be more expensive than rhodium. Per-kilogram prices of some synthetic radioisotopes range to trillions of dollars.