Why Does the Moon Glow? Causes of Illumination

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Discussion Overview

The discussion centers on the reasons behind the Moon's illumination as observed from Earth, exploring the causes of its glow, including the role of sunlight and the Moon's surface properties. The scope includes conceptual explanations and technical reasoning regarding albedo and light reflection.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • Some participants propose that the Moon glows due to sunlight reflecting off its surface.
  • Others argue that the Moon's surface has a high albedo, contributing to its brightness.
  • One participant notes that the Moon has a low albedo, reflecting approximately 14% of the light, comparing it to coal.
  • Another participant suggests that while the Moon reflects more light than a perfectly diffuse surface, it is not a Lambertian reflector.
  • Some participants mention the visibility of the Moon during the day, indicating it appears dimmer against the bright sky.

Areas of Agreement / Disagreement

Participants generally agree that sunlight is the source of the Moon's illumination, but there are differing views on the specifics of its albedo and how it compares to other materials.

Contextual Notes

There are unresolved aspects regarding the exact nature of the Moon's reflectivity and how it interacts with sunlight, as well as the implications of comparing its albedo to other surfaces.

dirtypunk
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why does the moon appear to glow from our view on earth? what causes the illumination?
 
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The sun

A flashlight and an orange will also let you work out why we see cresent, full and half moons
 
Yes the reason it glows is the sun but the cause is because the surface of the Moon has an extremely high albedo (high-reflectivity).
 
Kevin_Axion said:
Yes the reason it glows is the sun but the cause is because the surface of the Moon has an extremely high albedo (high-reflectivity).

The moon has rather low albedo, only reflecting ~14% of the light that hits it...similar to coal. It looks bright at night because it's lit by the sun against a black sky...it's like a lump of coal, but sunlit coal, in an otherwise perfectly dark room. (okay, a smattering of tiny, dim pinprick lights for the stars)

When seen in the day, with your eyes adapted to sunlight, it's much dimmer, largely blending in with the daytime sky.
 
cjameshuff said:
The moon has rather low albedo, only reflecting ~14% of the light that hits it...similar to coal.

Yep. Coal... Pavement...
 
Although it does reflect more than a diffuse flat 0.12 albedo surface so it's not really a fair comparison - it's far from a Lambertian reflector.
 

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