In clear weather conditions, the naked eye can see objects in the sky that are light-years away, which suggests that the human vision range is virtually infinite.
However, our ability to see distant objects depends on factors like the amount of light that enters the eye, the size and brightness of an object, and our overall vision health.
Read on as we discuss these factors and more, including how far the human eye can see and visual ranges in different conditions.
Before discussing how far human eyes can see, it’s important to explain how the human eye works.
Your eyes have different structures that work together to help you see. These structures include the:
The process of how your eyes receive and interpret light to enable vision involves the following steps:
The Triangulum Galaxy, also called Messier 33, is the most distant object a person can see from Earth when there is no light pollution and their eyesight is healthy.
We’re talking about a galaxy three million light-years away. However, not everyone can see objects this far.
Different factors affect how far the naked eye can see, including:
Your eye health is an important factor in determining the distance at which your eyes can see clearly. If your eyes and vision are in good health, you may be able to see farther than someone with an eye condition, like cataracts.
This is known as visual acuity. It determines how sharp your vision is at a certain distance.
For instance, 20/20 vision is considered normal vision. It means you can see objects at a distance of 20 feet as clearly as someone with normal or average eyesight.
20/30 vision means you can see an object 20 feet away as clearly as someone with normal eyesight can see it from 30 feet.
It is easier for the human eye to see bigger objects than smaller objects, as they reflect more light. Photons are the light particles produced by bright objects. So, the higher the number of photons that reach your eyes, the easier it is for you to see it.
Buildings, fog, trees, and clouds can block your view and affect your ability to see something at a certain distance, regardless of how far you can see.
When the skies are clear and nothing obstructs your line of sight, the curvature of the Earth’s surface creates a horizon. The surface gradually curves away from your line of sight, causing distant objects to disappear from view as they fall below this line.
There is no maximum distance the naked human eye can see when looking at the sky. That’s why you can see stars from galaxies far away.
The situation is a bit different when looking at the horizon.
When standing at ground level, the Earth’s curvature limits your visible distance to approximately 3 miles. Beyond this point, the curvature obstructs your view of more distant objects.
However, from the top of the Burj Khalifa in Dubai, the tallest structure in the world, you would potentially be able to see up to 50 miles. This higher vantage point extends your line of sight, allowing you to see further than you could at ground level.
How far you can see varies significantly based on environmental conditions and individual factors. The following variables provide insight into some of the boundaries and potentials of human vision:
This occurs when the air contains a high concentration of water droplets. It reduces visibility, limiting the human eye’s vision range to less than a 3,280-foot distance.
Snow reduces visibility, but this varies depending on the type of snowfall, such as blizzards, snowbursts, or blowing snow. For example, a person can only see within a quarter mile (approximately 440 yards) in a blizzard.
Unless you’re in a very well-lit area, there’s typically less light at night. The less light there is, the less light that reaches the retina. This makes it difficult to create a clear image.
This is why visibility at night can feel like looking at pixelated images. However, you may find it easier to spot brighter objects, such as stars, as these emit more light particles.
As you get older, you may also have an increased risk for night vision problems, so you may consult your eye doctor for advice.
This is known as nearsightedness and is characterized by seeing near objects clearly but having blurry vision when looking at a distance.
How far a myopic person can see depends on their visual acuity. For example, someone with 20/30 vision may still have relatively good distance vision, whereas someone with 20/100 vision has blurry distance vision.
If you’re having trouble seeing things far away, or your vision is getting blurry, it might be time to get your eyes checked. You could need a new eye prescription.
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