Title: evidence Earth is round ships horizon Eratosthenes NASA NOAA education at DuckDuckGo

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## [Empirical evidence for the spherical shape of Earth - Wikipedia](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FEmpirical_evidence_for_the_spherical_shape_of_Earth&rut=1de0a1982c2cc8ac3a6d32e23142bda832729c752a31d78575720023aac4f3f0)

[![Image 1](https://external-content.duckduckgo.com/ip3/en.wikipedia.org.ico)](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FEmpirical_evidence_for_the_spherical_shape_of_Earth&rut=1de0a1982c2cc8ac3a6d32e23142bda832729c752a31d78575720023aac4f3f0)[en.wikipedia.org/wiki/Empirical_evidence_for_the_spherical_shape_of_Earth](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FEmpirical_evidence_for_the_spherical_shape_of_Earth&rut=1de0a1982c2cc8ac3a6d32e23142bda832729c752a31d78575720023aac4f3f0)

[Empirical **evidence** for the spherical shape of **Earth** A sequence of pictures taken at Strait of Magellan, Chile, showing a tanker **ship** sailing towards the camera and rising over the **horizon**, demonstrating the **Earth's** curvature. Distance at first picture is about 18 km which would imply a theoretical **horizon** vertical drop of about 23 meters.](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FEmpirical_evidence_for_the_spherical_shape_of_Earth&rut=1de0a1982c2cc8ac3a6d32e23142bda832729c752a31d78575720023aac4f3f0)

## [90 Years of Our Changing Views of Earth - NASA](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fwww.nasa.gov%2Fhistory%2F90%2Dyears%2Dof%2Dour%2Dchanging%2Dviews%2Dof%2Dearth%2F&rut=27a9c47a20e0b0a059b6f31bbafa13ae49fa620af1c05bbc3a2c0eb500ec1be7)

[![Image 2](https://external-content.duckduckgo.com/ip3/www.nasa.gov.ico)](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fwww.nasa.gov%2Fhistory%2F90%2Dyears%2Dof%2Dour%2Dchanging%2Dviews%2Dof%2Dearth%2F&rut=27a9c47a20e0b0a059b6f31bbafa13ae49fa620af1c05bbc3a2c0eb500ec1be7)[www.nasa.gov/history/90-years-of-our-changing-views-of-earth/](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fwww.nasa.gov%2Fhistory%2F90%2Dyears%2Dof%2Dour%2Dchanging%2Dviews%2Dof%2Dearth%2F&rut=27a9c47a20e0b0a059b6f31bbafa13ae49fa620af1c05bbc3a2c0eb500ec1be7)

[Indirect **evidence** of the **Earth's** spherical shape has existed for a long time, but the photographic proof was lacking until well into the 20th century. The ancient Greeks believed the **Earth** was **round** and calculated its circumference with remarkable accuracy, while observers inferred our planet's spherical shape as it cast a curved shadow on the Moon during lunar eclipses. With the advent of ...](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fwww.nasa.gov%2Fhistory%2F90%2Dyears%2Dof%2Dour%2Dchanging%2Dviews%2Dof%2Dearth%2F&rut=27a9c47a20e0b0a059b6f31bbafa13ae49fa620af1c05bbc3a2c0eb500ec1be7)

## [Is Earth Round? - ABOUT SCIENCE](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fabout%2Dscience.org%2Flesson%2Fis%2Dearth%2Dround%2F&rut=ba87be43121784b7b9c06415dfcbac0e75ffd1430776e3375bf13d332b21db96)

[![Image 3](https://external-content.duckduckgo.com/ip3/about-science.org.ico)](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fabout%2Dscience.org%2Flesson%2Fis%2Dearth%2Dround%2F&rut=ba87be43121784b7b9c06415dfcbac0e75ffd1430776e3375bf13d332b21db96)[about-science.org/lesson/is-earth-round/](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fabout%2Dscience.org%2Flesson%2Fis%2Dearth%2Dround%2F&rut=ba87be43121784b7b9c06415dfcbac0e75ffd1430776e3375bf13d332b21db96) 2026-03-16T00:00:00.0000000

[**Horizon** and **ship** observations: The most accessible **evidence** comes from watching **ships** disappear bottom-first over the **horizon**, indicating curvature. Lunar eclipses: During a lunar eclipse, **Earth** casts a **round** shadow on the Moon regardless of the eclipse's timing, possible only if **Earth****is****round**.](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fabout%2Dscience.org%2Flesson%2Fis%2Dearth%2Dround%2F&rut=ba87be43121784b7b9c06415dfcbac0e75ffd1430776e3375bf13d332b21db96)

## [The History of Geodes: Global Positioning Tutorial](https://duckduckgo.com/l/?uddg=https%3A%2F%2Foceanservice.noaa.gov%2Feducation%2Ftutorial_geodesy%2Fgeo02_hist.html&rut=36f92fd8f0b2f882bae4dfffc1d1646743a850b69fe756eeee5e4fef4ab9e102)

[![Image 4](https://external-content.duckduckgo.com/ip3/oceanservice.noaa.gov.ico)](https://duckduckgo.com/l/?uddg=https%3A%2F%2Foceanservice.noaa.gov%2Feducation%2Ftutorial_geodesy%2Fgeo02_hist.html&rut=36f92fd8f0b2f882bae4dfffc1d1646743a850b69fe756eeee5e4fef4ab9e102)[oceanservice.noaa.gov/education/tutorial_geodesy/geo02_hist.html](https://duckduckgo.com/l/?uddg=https%3A%2F%2Foceanservice.noaa.gov%2Feducation%2Ftutorial_geodesy%2Fgeo02_hist.html&rut=36f92fd8f0b2f882bae4dfffc1d1646743a850b69fe756eeee5e4fef4ab9e102)

[The accepted measurement of the **Earth's** circumference today is about 24,855 miles. Given the simple tools and technology that **Eratosthenes** had at his disposal over 2,000 years ago, his calculations were quite remarkable. **Eratosthenes'** calculations were based on two assumptions. The first was that Syene lay on the Tropic of Cancer.](https://duckduckgo.com/l/?uddg=https%3A%2F%2Foceanservice.noaa.gov%2Feducation%2Ftutorial_geodesy%2Fgeo02_hist.html&rut=36f92fd8f0b2f882bae4dfffc1d1646743a850b69fe756eeee5e4fef4ab9e102)

## [Spherical Earth - Wikipedia](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FSpherical_Earth&rut=84197007dc8571c88a7f0a9fc185d0f245985067cdcefb9c06dd539795b40044)

[![Image 5](https://external-content.duckduckgo.com/ip3/en.wikipedia.org.ico)](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FSpherical_Earth&rut=84197007dc8571c88a7f0a9fc185d0f245985067cdcefb9c06dd539795b40044)[en.wikipedia.org/wiki/Spherical_Earth](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FSpherical_Earth&rut=84197007dc8571c88a7f0a9fc185d0f245985067cdcefb9c06dd539795b40044)

[Spherical **Earth** or **Earth's** curvature refers to the approximation of the figure of the **Earth** as a sphere. The earliest documented mention of the concept dates from around the 5th century BC, when it appears in the writings of Greek philosophers. [1][2] In the 3rd century BC, Hellenistic astronomy established the roughly spherical shape of **Earth** ...](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FSpherical_Earth&rut=84197007dc8571c88a7f0a9fc185d0f245985067cdcefb9c06dd539795b40044)

## [The Round Earth and Christopher Columbus--lesson plan #12 - NASA](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fpwg.gsfc.nasa.gov%2Fstargaze%2FLcolumb.htm&rut=134e3f494566b6bf8896b4afe000a8454a8faf18fb7423f4835adffbb0156cea)

[![Image 6](https://external-content.duckduckgo.com/ip3/pwg.gsfc.nasa.gov.ico)](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fpwg.gsfc.nasa.gov%2Fstargaze%2FLcolumb.htm&rut=134e3f494566b6bf8896b4afe000a8454a8faf18fb7423f4835adffbb0156cea)[pwg.gsfc.nasa.gov/stargaze/Lcolumb.htm](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fpwg.gsfc.nasa.gov%2Fstargaze%2FLcolumb.htm&rut=134e3f494566b6bf8896b4afe000a8454a8faf18fb7423f4835adffbb0156cea)

[Goals: The student will Understand the concept of the **horizon** at sea as **evidence** that the **Earth****is****round**: the gradual disappearance of distant objects, bottom before top, and their reappearance if we climb higher. Calculate the way Erathosthenes estimated the size of the **Earth**. Know of other estimates of the size of the **Earth** before Columbus, and the origin of the idea of "sailing west to ...](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fpwg.gsfc.nasa.gov%2Fstargaze%2FLcolumb.htm&rut=134e3f494566b6bf8896b4afe000a8454a8faf18fb7423f4835adffbb0156cea)

## [What Scientific Evidence Proves the Earth Is a Sphere?](https://duckduckgo.com/l/?uddg=https%3A%2F%2Ffactually.co%2Ffact%2Dchecks%2Fscience%2Fscientific%2Devidence%2Dearth%2Dsphere%2Dbb48e4&rut=3e5a66c976231feda057f491020b291647d0318accb541c447119ae87ee2dc19)

[![Image 7](https://external-content.duckduckgo.com/ip3/factually.co.ico)](https://duckduckgo.com/l/?uddg=https%3A%2F%2Ffactually.co%2Ffact%2Dchecks%2Fscience%2Fscientific%2Devidence%2Dearth%2Dsphere%2Dbb48e4&rut=3e5a66c976231feda057f491020b291647d0318accb541c447119ae87ee2dc19)[factually.co/fact-checks/science/scientific-evidence-earth-sphere-bb48e4](https://duckduckgo.com/l/?uddg=https%3A%2F%2Ffactually.co%2Ffact%2Dchecks%2Fscience%2Fscientific%2Devidence%2Dearth%2Dsphere%2Dbb48e4&rut=3e5a66c976231feda057f491020b291647d0318accb541c447119ae87ee2dc19) 2026-05-03T00:00:00.0000000

[These lines of **evidence** include geometric measurements of shadows and star positions, the way **ships** disappear over the **horizon**, circumnavigation and orbital photography, and precise gravitational and satellite measurements that refine the sphere into an ellipsoid and the geoid [3] [4] [5].](https://duckduckgo.com/l/?uddg=https%3A%2F%2Ffactually.co%2Ffact%2Dchecks%2Fscience%2Fscientific%2Devidence%2Dearth%2Dsphere%2Dbb48e4&rut=3e5a66c976231feda057f491020b291647d0318accb541c447119ae87ee2dc19)

## [Ancient Observatories | Educators - Sun-Earth Day](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fscience.gsfc.nasa.gov%2Fattic%2Fsunearthday.nasa.gov%2F2005%2Fastronomer%2Fact_5.htm&rut=ffb20b10f3d2a5857d5c30f9af04e8ac4d32b938a5a1ab288c21909989400f35)

[![Image 8](https://external-content.duckduckgo.com/ip3/science.gsfc.nasa.gov.ico)](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fscience.gsfc.nasa.gov%2Fattic%2Fsunearthday.nasa.gov%2F2005%2Fastronomer%2Fact_5.htm&rut=ffb20b10f3d2a5857d5c30f9af04e8ac4d32b938a5a1ab288c21909989400f35)[science.gsfc.nasa.gov/attic/sunearthday.nasa.gov/2005/astronomer/act_5.htm](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fscience.gsfc.nasa.gov%2Fattic%2Fsunearthday.nasa.gov%2F2005%2Fastronomer%2Fact_5.htm&rut=ffb20b10f3d2a5857d5c30f9af04e8ac4d32b938a5a1ab288c21909989400f35)

[ACTIVITY V ACTIVITY V: Using the **eratosthenes** method, calculate the circumference of the **Earth** This is a tad off topic but symbolizes the use of pre telescopic observations of the sun to understand our world. Over two thousand years ago, the knowledge existed that the **Earth** was **round**. Observing the changing height of the North Star or watching **ship** masts disappear over the **horizon** after the ...](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fscience.gsfc.nasa.gov%2Fattic%2Fsunearthday.nasa.gov%2F2005%2Fastronomer%2Fact_5.htm&rut=ffb20b10f3d2a5857d5c30f9af04e8ac4d32b938a5a1ab288c21909989400f35)

## [The Shape of the Earth - The European Southern Observatory](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fwww.eso.org%2Fpublic%2Foutreach%2Feduoff%2Fseaspace%2Fnavigation%2Fnavastro%2Fnavastro%2D1.html&rut=e87f9ee96107e27a75767fcd2137ef0c3e8d2e189e6f61f64930182fb79a9f23)

[![Image 9](https://external-content.duckduckgo.com/ip3/www.eso.org.ico)](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fwww.eso.org%2Fpublic%2Foutreach%2Feduoff%2Fseaspace%2Fnavigation%2Fnavastro%2Fnavastro%2D1.html&rut=e87f9ee96107e27a75767fcd2137ef0c3e8d2e189e6f61f64930182fb79a9f23)[www.eso.org/public/outreach/eduoff/seaspace/navigation/navastro/navastro-1.html](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fwww.eso.org%2Fpublic%2Foutreach%2Feduoff%2Fseaspace%2Fnavigation%2Fnavastro%2Fnavastro%2D1.html&rut=e87f9ee96107e27a75767fcd2137ef0c3e8d2e189e6f61f64930182fb79a9f23)

[When a **ship** sails away from the coast, it seems to disappear gradually behind the **horizon**. The next scientific step, directly measuring the size of our planet, was performed by Erathostenes (276-194 B.C.). In 1996 - 97, several EAAE - Astronomy On-Line students have repeated these measurements: click to see a general description.](https://duckduckgo.com/l/?uddg=https%3A%2F%2Fwww.eso.org%2Fpublic%2Foutreach%2Feduoff%2Fseaspace%2Fnavigation%2Fnavastro%2Fnavastro%2D1.html&rut=e87f9ee96107e27a75767fcd2137ef0c3e8d2e189e6f61f64930182fb79a9f23)

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