Why the Sun Looks Smaller at Higher Altitudes

Elizabeth Borneman


Why is it that astronomers and their telescopes are commonly perched on the highest mountaintops? Atmospheric observations are often easier to make higher up, when there isn’t so much distortion or pollution in the way of an accurate look at the night sky.

Closer to sea level atmospheric distortion can include heat, dust, moisture, air pollution, and other materials that cloud the air. Up high these distortions are minimized.

The Sun Looks More Distorted at Lower Elevations

One way to see this kind of distortion is to stand near sea level and hold your thumb up to the sky, in front of the Sun (make sure not to stare directly into the Sun. The sun’s rays, or aureole, will expand far beyond what your finger can block.

This blur of the sun’s boundaries is caused by atmospheric distortions like dust, heat, air pollution, moisture, haze, and other materials in the air.

Free weekly newsletter

Fill out your e-mail address to receive our newsletter!

A setting Sun over the Arctic Ocean with chunks of ice floating in the ocean.
At lower elevations, dust, pollution, and moisture in the air can distort the Sun’s rays. Photo: Sun over the Arctic Ocean on Sept. 9, 2009 by Patrick Kelley, U.S. Coast Guard, public domain.

A fingertip held out at arm’s length is about one-half a degree of sky, which is about the same amount of space that the sun and moon take up from the same perspective on Earth.

Atmospheric Distortions of the Sun are Less at Higher Altitudes

Up high, these atmospheric distortions are much less. The atmosphere is much thinner higher up, making it difficult for distortions to appear and stay for very long. From their positions on high mountaintops, astronomers can view the sky both at night and during the day without things getting in the way.

An artistic view of the Earth and the Sun against a dark background.
Views of the Sun are much less distorted at higher elevations on Earth. Image: NASA, public domain.

Mountaintop viewpoints like Mona Lea in Hawaii give scientists the ability to look deep into space to the extent of their technological abilities.

At an elevation of 10,000 feet above sea level (or 3,050 meters), the sun looks very different. The sun’s disk can be easily placed behind your thumb if you hold it out at arm’s length.

The sun’s aureole is a lot smaller because there is less atmospheric distortion from dust, pollution, or moisture spreading out the sun’s visible rays.


Sun Size and Altitude, Universities Space Research Association.

Photo of author
About the author
Elizabeth Borneman
My name is Elizabeth Borneman and I am a freelance writer, reader, and coffee drinker. I live on a small island in Alaska, which gives me plenty of time to fish, hike, kayak, and be inspired by nature. I enjoy writing about the natural world and find lots of ways to flex my creative muscles on the beach, in the forest, or down at the local coffee shop.