Seeing stars during the day seems like a concept straight out of a fairy tale, but it is scientifically possible under specific conditions. Normally, stars are obscured by the sun's bright light scattering in the atmosphere. However, if you are at the bottom of a tall chimney or a deep well, your field of view narrows significantly due to the structure’s vertical walls. This setup essentially creates a natural pinhole camera with a very limited angle of view, reducing the amount of scattered sunlight that enters your eye.
In such a scenario, looking upwards through this narrow tube filters out a significant portion of the blue sky, which is just scattered sunlight. What remains is a darker patch of the sky, allowing the brighter stars to become visible. The concept behind this involves limiting the amount of sunlight entering your line of sight, which minimizes the blue light caused by atmospheric scattering, thereby diminishing the sky’s brightness. This concept can also explain why the sky at high altitudes appears darker, as thinner air scatters less sunlight.
Despite the scientific explanation, observing stars from the bottom of a deep, narrow structure during the day remains a challenging feat. The conditions need to be just right: the sky must be clear, and the sun needs to be positioned away from your direct line of sight up the shaft. Moreover, the stars that might be seen are generally limited to the very brightest, such as Sirius or Canopus.
This technique of observing stars from such locations highlights interesting principles of optics and atmospheric science. While it's an uncommon method and less practical than simply waiting for nightfall, it serves as a fascinating demonstration of how our environment can be manipulated to reveal the cosmos at times and in ways we might not expect. This method also underscores the ingenuity humans have applied throughout history to understand the universe, even before the advent of modern telescopes and astronomical equipment.
