Claim: Is the earth flat?

First requested: April 7, 2026 at 10:17 AM
3%

IsItCap Score

Truth Potential Meter

Not Credible

AI consensusMedium

Grader consensus is moderate.
Range 0%–10% (spread Δ10).
The graders lean in the same direction but differ on strength. Skim the summary and sources.
Read analysis summary

OpenAI Grade

0%
20%
40%
60%
80%
10%

Perplexity Grade

0%
20%
40%
60%
80%
0%

Google Gemini Grade

0%
20%
40%
60%
80%
0%

Analysis Summary

The claim that the Earth is flat is false. Mainstream scientists and educators overwhelmingly support the understanding that the Earth is a sphere based on extensive evidence. Alternative sources, often driven by conspiracy theories, dispute this by promoting debunked arguments and misinformation about scientific observations and evidence. All three graders point in the same direction, with minor differences. OpenAI comes in highest (10%), while Gemini is lowest (0%). While some individuals and groups assert that the Earth is flat, their claims are largely based on misunderstandings or misinterpretations of scientific principles. Opposing sources argue that the spherical nature of the Earth is supported by centuries of scientific observations, such as the curvature of the horizon and the way ships disappear from view. These counterarguments reinforce the established scientific consensus and do not alter the overall verdict of falsehood regarding the flat Earth claim.

Source quality

Truth (from sources)1.00 / 10
Source reliability9.00 / 10
Source independence8.00 / 10

Claim checks

Fits established facts10.00 / 10
Logical consistency10.00 / 10
Expert consensus10.00 / 10

Source Analysis

Common arguments (from Perplexity)
For
  • Historical disagreements suggest uncertainty in shape.
  • Some distrust space photos as fabricated.
  • Personal observations seem flat locally.
Against
  • Horizon effect shows convexity when climbing high.
  • Science affirms spherical Earth with repeated proofs.
  • Ship masts appear over horizon before hulls.

Mainstream Sources

Publication

bbcearth.com

Title

Why some people believe the Earth is flat | BBC Earth

Summary

There have been disagreements throughout history over whether the planet is flat or spherical. The simple answer is that <strong>we live on a bumpy, mountainous, cavernous globe</strong>. Earth Lab’s Dom Burgess shines a light on the science behind the real ...

Source details

Type: Major Media
No Date

Publication

answersingenesis.org

Title

Is the Earth Flat? | Answers in Genesis

Summary

But these arguments have been repeatedly disproven. Those who believe the earth is flat are flatly mistaken—<strong>science does not call into question a spherical earth but rather affirms it</strong>.

Source details

Type: Blog
No Date

Publication

uwr.edu.pl

Title

Is the Earth flat? - Uniwersytet Wrocławski

Summary

The first indication that it is not, however, is the effect of the horizon. Looking around we can only see places up to a certain distance. If we climb a hill or a tower, we will see further away. This means that the Earth must be convex. What could we see from Wrocław if the Earth were flat?

Source details

Type: Primary

Alternative Sources

Publication

pursuit.unimelb.edu.au

Title

Why do some people believe the Earth is flat? | Pursuit by the University of Melbourne

Summary

A flat Earth map drawn by Orlando Ferguson in 1893. Picture: Wikimedia · As well as observations of the sun and its shadows, Ms Jayasuriya says many scientists throughout history continued to gather observations and evidence that the Earth is spherical including: That we see the top of a ship’s mast coming into port and not the entire ship

Source details

Type: Primary

Publication

space.com

Title

How to debate a flat-Earther - Proven scientific arguments and strategies | Space

Summary

Paul M. Sutter is an astrophysicist ... in Space. For many centuries a wealth of scientific evidence has demonstrated that <strong>the Earth is a sphere</strong>....

Source details

Type: Major Media

Publication

astronomy.com

Title

Why Earth is not flat: The conspiracy debunked

Summary

They claim that light, perspective, ... at all. Furthermore, flat earthers claim that <strong>all images of the globe are fraudulent inventions and all testimony from astronauts is false</strong>....

Source details

Type: Major Media

Analysis Breakdown

True/False Spectrum (1.0)Source Credibility (9.0)Bias Assessment (8.0)Contextual Integrity (10.0)Content Coherence (10.0)Expert Consensus (10.0)80%

Understanding the Grades

Metrics

  • Verifiability: Evidence strength
  • Source Quality: Credibility assessment
  • Bias: Objectivity measure
  • Context: Completeness check

Scale

  • 8-10: Excellent
  • 6-7: Good
  • 4-5: Fair
  • 1-3: Poor

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