THE Earth’s ocean could one day turn purple – and scientists say it used to be a totally different colour. The Earth’s seas have been predominantly blue for around the last 600 mi… ...

On a bright, clear day, the sky stretches above us in a brilliant shade of blue. But have you ever wondered why? The answer lies in a fascinating phenomenon known as Rayleigh scattering ...

"The blue wavelengths of light are scattered, similar to the scattering of blue light in the sky, but absorption is a much larger factor than scattering for the clear ocean water.

Between 3.8 and 1.8 billion years ago, during the Archean eon, the seas weren’t blue at all. Back then, high levels of dissolved iron from volcanic vents and eroded rock turned the oceans green.

The blue colour of sky has nothing to do with colour of the ocean, it is blue due to… If Earth had no atmosphere—like the Moon—there would be no scattering, and the sky would remain black ...