Green Lion Classical Colours
There are four classical Greek elements: air / wind, earth, fire and water. The four classical elements were accepted as theory for over 2000 years, and were later incorporated into the knowledge of alchemy. Each is associated with a colour:
- air - yellow
- earth - black
- fire - red
- water - white
Medieval Concept of the Universe
The classical elements were associated with the idea of time in the work of Medieval alchemists and philosophers. The interior dial in Wells Cathedral is a working model of the medieval concept of the universe, with the Earth and its four elements - earth, air, fire, and water - in the centre, surrounded by the first heavenly sphere of the moon, which rotates around it.
A spectrograph is used to obtain and record an astronomical spectrum. The spectrograph splits or disperses the light from an object into its component wavelengths so that it can be recorded then analysed.
- 1666 - The English astronomer and mathematician Isaac Newton recorded the spectrum of sunlight by drawing it. Newton set up a prism near his window, and projected a spectrum 22 feet onto the far wall. Further, to prove that the prism was not colouring the light, he refracted the light back together.
- 1801 - Dark absorption lines in the solar spectrum discovered by William Wollaston.
- 1814 - Joseph von Fraunhofer invented the spectroscope, and discovered 574 dark lines appearing in the solar spectrum.
- 1868 - Helium was first noticed when French astronomer, Jules-César Janssen, discovered lines in a spectrograph of the sun which belonged to no known element.
- 24 April 1990 - Hubble Space Telescope carried into orbit by the space shuttle Discovery.
Attributes of stellar objects are used to measure time taken for visible light to travel (light years). In astronomy:
- Redshift occurs when visible light is shifted towards the red end of the electromagnetic spectrum due to the Doppler effect or other gravitationally-induced effects.
- Conversely, a decrease in wavelength is called blue shift.
Four Colours of Classical Greece
Caius Plinius Secundus, (AD 23 - AD 79) made the claim that the painters of classical Greece only used a limited palette in their work and believed that additional colours were not needed:
"It was with four colours only that Apelles, Echion, Melanthius, and Nicomachus, those most illustrious painters, executed their immortal works... and yet a single picture of theirs has sold before now for the treasures of whole cities.... Everything, in fact, was superior at a time when the resources of art were so much fewer than they now are."
Pliny's four colours were based on actual pigments rather than abstract scheme of classification, naming for example, Attic yellow and "red from sinope on the Black Sea". The discolouraton of many of the pigments from Greek and Roman art with time has encouraged the appearance of a limited palette of colours, beyond the basic idea of the four elemental colours. Archaeology has corrected some impressions and increased our knowledge of the past. Roman textiles have been found with madder and indigo dyes, replacing the old Imperial Purple (purpura).