Why Aren't the Stars Visible at Night?

  • Thread starter lufc88
  • Start date
  • Tags
  • #1

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.
Last edited by a moderator:
Science news on Phys.org
  • #2
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.

1. Why can't we see stars during the day?

During the day, the bright light from the sun outshines the light from the stars, making them difficult to see. The sun's light is scattered and reflected by the Earth's atmosphere, making it almost impossible for stars to compete in brightness.

2. Why do stars only appear at night?

Stars are always present in the sky, but they are only visible at night because the Earth rotates away from the sun, allowing the dark side of the planet to face the sky. This lack of sunlight allows us to see the stars more clearly.

3. Why do some stars appear brighter than others?

The brightness of a star depends on its distance from Earth and its size. The closer a star is to Earth, the brighter it will appear. Additionally, larger stars emit more light and thus appear brighter in the night sky.

4. Why do stars twinkle?

Stars appear to twinkle due to the Earth's atmosphere. As light from a star travels through the atmosphere, it is refracted or bent, causing the star's position and brightness to appear to change. This creates the twinkling effect that we see.

5. Why do some stars have different colors?

The color of a star is determined by its temperature. Hotter stars emit more blue light, while cooler stars emit more red light. This is why we see stars with different colors in the night sky. The color of a star can also be affected by the composition of gases in its atmosphere.

Suggested for: Why Aren't the Stars Visible at Night?