Fact check: Clouds can appear behind the sun in photos due to optical illusion

Kate S. Petersen, USA TODAY
·3 min read

The claim: Photos appearing to show clouds behind the sun suggest it orbits the earth, isn't millions of miles away

Earth orbits the sun, a star located more than 90 million miles away at the center of the solar system.

However, some social media users claim a set of photos challenges this scientific conclusion about the distance to the sun and its position relative to the Earth.

One Facebook post dated Jan. 4 includes what appear to be photos of the sun with clouds both in front of the sun and behind it.

"If the Sun is 93 million miles away, how are there clouds behind it?" reads the post. "Doesn't make sense, unless the Sun is orbiting around the Earth."

The post accumulated more than 600 interactions in a few weeks.

However, the clouds are, in fact, located between the sun and the Earth's surface, according to Rona Oran, a computational space physicist at Massachusetts Institute of Technology. When clouds appear behind the sun in a photo, it is an optical illusion.

USA TODAY found additional versions of the claim on Facebook dating back to 2019. It was also posted recently on Twitter.

Special access for subscribers! Click here to sign up for our fact-check text chat

USA TODAY reached out to the social media users who shared the claim for comment.

The appearance of clouds behind the sun is an optical illusion

The post appears to be related to a "Flat Earth" belief system — a collection of theories asserting Earth is flat rather than spherical. Some Flat Earth adherents believe the sun is smaller and closer to the Earth, moving in circles over the Earth, ostensibly low enough to contact the clouds.

However, the photos in the post do not actually support the theory of a small, close sun.

"It's an optical illusion," Oran told USA TODAY. "All the clouds are ... in front of the sun."

The distance between Earth and the sun — roughly 93 million miles — has been established through multiple lines of evidence. These include radar measurements, geometric calculations based on ground observations, and a spacecraft mission to the sun.

The effect seen in the picture is related to how transparent different clouds are.

When a photo is taken of a relatively opaque cloud passing between the sun and a photographer, the cloud covers up enough of the sun's light that the cloud shows up in the resulting photo.

Fact check: NASA did not deny warming or say polar ice has increased since 1979

But when a very translucent cloud passes between the sun and the photographer, the part of the cloud in front of the sun doesn't show up in the photo. This is because too much light passes through the cloud and strikes the camera's film or sensor.

"It's like an overexposure," said Oran.

This gives the impression that part of the cloud has disappeared behind the Sun, she said. But it has not.

Our rating: False

Based on our research, we rate FALSE the claim that photos appearing to show clouds behind the sun suggest it orbits the Earth and is not millions of miles away. The clouds only appear to be behind the sun when too much light passes through the cloud and strikes the camera's film or sensor, causing overexposure.

Our fact-check sources:

Thank you for supporting our journalism. You can subscribe to our print edition, ad-free app or electronic newspaper replica here.

Our fact-check work is supported in part by a grant from Facebook.

This article originally appeared on USA TODAY: Fact check: Photos do not prove sun close and orbiting Earth