Why Does Earth Appear Mostly Blue from Space?

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Discussion Overview

The discussion revolves around the reasons why Earth appears predominantly blue when viewed from space. Participants explore the properties of light, reflection, and the composition of Earth's surface, focusing on the implications of these factors for the observed color of the planet.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant questions why Earth appears blue rather than red, suggesting that higher energy light should be absorbed and radiated away in lower wavelengths.
  • Another participant emphasizes that the light observed is reflected light from Earth's surface, not blackbody radiation.
  • A third participant reiterates that the visible light seen in cameras is indeed reflected light, not emitted light.
  • It is proposed that a significant portion of incoming sunlight is reflected away without interaction, with a suggestion that water's properties lead to more reflection of blue light and absorption of red light.

Areas of Agreement / Disagreement

Participants generally agree on the nature of the light being reflected, but there are differing views on the reasons for the predominance of blue light and the implications of Earth's surface properties.

Contextual Notes

Some assumptions about light absorption and reflection properties are not fully explored, and the discussion does not resolve the underlying reasons for the observed color of Earth.

rootone
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Why does the Earth appear blue (mostly) when observed from outside.
Blue light is more energetic than red and lower wavelength.
Processes which happen on Earth seem to suggest that higher energy light arriving should be absorbed in one way or another and eventually some of it radiated away in infrared and lower wavelength.
Why does the Earth not look red when seen from outside?
 
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What does Earth's surface consist of? The reflected light is not blackbody radiation, it is reflected light.
 
As Orodruin said, it is light that is reflected from the Earth that is seen in visible light cameras, not the light emitted by the Earth.
 
OK, so on the sunlight side of Earth a high proportion of all the incoming light is just reflected away and doesn't otherwise interact.
I guess the reason why the reflected light is more in the blue end of the visible spectrum is simply because that is a just property of water - it reflects bluer light and absorbs more red.
 
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