Why Aren't the Stars Visible at Night?

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SUMMARY

The visibility of stars at night is primarily explained by Olbers' Paradox, which posits that the night sky is dark despite the vast number of stars due to the inverse square law of light intensity. As distance increases, the intensity of light diminishes, making stars less visible to the naked eye. Additionally, the quantization of light means there is a minimum brightness level that our eyes cannot detect, further contributing to the darkness of the night sky. The discussion highlights the balance between the increasing number of stars and the decreasing brightness of their light.

PREREQUISITES
  • Understanding of Olbers' Paradox
  • Familiarity with the inverse square law of light intensity
  • Basic knowledge of light quantization
  • Awareness of astronomical concepts related to star visibility
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  • Research the implications of Olbers' Paradox in cosmology
  • Study the inverse square law in detail with practical examples
  • Explore the concept of light quantization and its effects on visibility
  • Investigate the distribution of stars in the universe and its impact on night sky brightness
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Astronomy enthusiasts, students of physics, and anyone interested in understanding the reasons behind the darkness of the night sky will benefit from this discussion.

lufc88
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Isn't the reason the sky isn't bright at night ,due to all the stars, because the fact the stars aren't bright enough to be seen by the naked eye after a certain distance? So it doesn't necessarily depend on the fact the universe doesn't have to be infinite or expanding? I know the intensity of light decreases due to the inverse square law and I know that there would be a minimum level of brightness, as light is quantised, that would never be lower but would happen less frequent as the photons would be less frequent. But our eyes aren't that sensitive so eventually we would not see anything in terms of visible light.
 
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This is called Olbers' Paradox, and if you do forum search you'll find a plethora of threads explaining it. Wikipedia's article is also a good read.

In short, even though the light intensity falls down with square of the distance, the number of stars seen increases with square of the distance.
 

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