How Far Can the Human Eye See?

to see? Pretty far, as it turns out, if you're a person with normal visual acuity a rating of twenty twenty, and you gaze out in a horizontal line from around five feet or one and a half meters above the ground, you can see for about three miles or five kilometers into the distance, which is the point at which Earth's curvature bends away so that the surface is no longer

in view. And while your ability to discern objects depends upon their size and how much light the distant object emits or reflects on a dark night, it's possible to see a single candle flame from about one and a half miles or two and a half kilometers away. To understand how our eyes can see a distant object like a candle flame flickering, it helps to know something about how normal vision and the human eye work. A While visual acuity varies among individuals, the naked eye is definitely

an impressive piece of equipment. It's capable of twelve times the resolution of a high end smartphone's camera. We can perceive a nearly infinite range of colors and shapes, as will as detect very small changes in brightness and minute amounts of motion. Human vision is a complex, intricate process. A light emits from or reflects off of objects, and then passes through the cornea and the lens of the eye, a which bend and focus light onto the retina at

the back of the eye. There a layer of tiny nerve cells called rods and cones are activated by the light and send electrical impulses through the optic nerve to your brain, which creates an image or visual perception. For the article, this episode is based on How Stuff Works. Spoke with doctor Eric Lowell Singhman, a practicing optomologist with the University of Maryland Medical System and the Professor of

Optomology with the University of Maryland School of Medicine. He said, the eye turns light into biometric energy transmitted to the brain. Some nerve cells see colors, some see black and white, Some see motion only in one direction, others see motion in another. Direction, some see shapes, some just look at the overall ambient lighting. Together, those cells work as a team to tell your brain what to visualize, a transmitting

information about what's moving and what colors things are. The singman said, these are actually different, separate channels, and then your brain takes the images and converts them into something that your conscious mind can appreciate. In addition, the human visual system also transmits and creates visual information that you you aren't even necessarily aware of, for example, the amount of ambient light, which helps control your natural rhythms of

day and night. Without obstructions in the way, you can see about three miles where five kilometers into the distance from ground level before you reach the point where earth curves enough to block your view of what's on the ground. But that's based on a hypothetical person who's five feet or one and a half meters tall. If you're taller, you could see farther based just on your angle of sight. Similarly, the higher you go in elevation, the farther into the

distance you can see. A person looking out from the observation deck of the world's tallest building eight hundred and twenty eight meters skyscraper in Dubai that's about twenty seven hundred and seventeen feet. Reportedly can see for sixty miles or about one hundred kilometers, and our visual acuity extends beyond the horizon. Even if the curvature of the Earth didn't exist, and instead Earth was a flat surface, would have an uninterrupted visual angle from our eyes to the

farthest object visible. This is evidenced by the fact that we can see extremely distant objects in space. As long as the sky is clear and the object is bright enough on a dark night without light pollution, you should be able to see the Andromeda galaxy, which is two point five million light years away. That's the equivalent of fifteen quintillion miles or twenty four quintillion kilometers on Earth. Our atmosphere is also a major factor in how well

you can see distant objects. Theoretically, in a vacuum, there's no limit to how far away your eyes could see, since light rays can travel an infinite distance. But even though our air seems insubstantial, it actually contains a lot of stuff. Houstuffworks. Also spoke with doctor Timothy McCully, a professor and chair in the Department of Optomology and Visual Science with McGovern Medical School at UT Health Houston explained, you're seeing through the atmosphere and yellow particular matter in

the air is scattering the light. So depending on the medium that the light is traveling through, those electromagnetic waves will or will not reach your eyes. A similar problem occurs on a foggy day or night, or during rain or snow. That's why we're able to see that candle flame flickering a long way off when there's a dark, clear night sky, but not when the light is impeded by precipitation, even though we can see a glowing object

far in the distance. The human eye does have its limitations, especially when it comes to visual acuity, which is the scientific term for sharpness of vision. Our cone cells, the photoreceptors that are sensitive to red, green, and blue wavelengths of light, are concentrated in the macula, an area in the middle of the retina. Our sharpest vision is at the center of the macula, in a spot called the phobia that can zero in on a small part of

the world in front of you. A singmund said, you might think that you have a very wide visual field, but the reality is that your area of clearest vision is actually just a few degrees. You don't see the whole world clearly. If you take a big letter, eat a big as your hand and move it about fifteen to twenty degrees away to the side, you wouldn't be able to tell what that letter was. The clarity of your vision drops pretty quickly once you get off center.

That's why macular degeneration and eye condition in which the macula becomes damaged so that you lose that central vision, can be such a serious problem for people who get it. The risk increases as you get older. But your eyes are only part of the equation. That's evident in people who have some sort of brain injury that interferes with their vision, even if there's nothing wrong with their eyes. Singmund said, you've got to remember that the brain is

a really big part of this process. There are types of brain damage where you can't see something move, or where you can't recognize faces. You'll look and pick out an eye or a nose or mouth instead of the whole face. The brain can also perform tricks to make up for the eye's shortcomings. Singmann recalls the case of a patient who, after eye surgery, suddenly discovered that when he covered that eye, he couldn't see out of the

other but supposedly good eye. When a doctor examined the patient, it was discovered that he had a cataract, a natural clouding of the lens on that eye, but apparently had never noticed it because of his brain's ability to filter out the blur. Missingman said, that's a classic trick. The brain can shut things off. Today's episode is based on an article how far can the human Eye see? On

how stuffworks dot com written by Patrick J. Kiger. Brain Stuff is production by Heart Radio in partnership with how stuffworks dot Com and is produced by Tyler Klang. Four more podcasts from my heart Radio, visit the iHeartRadio app podcasts, or wherever you listen to your favorite shows. M