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> Nobody had a clue In the 3rd century BC, Aristarchus calculated that the Sun was between 18 and 20 times farther away from the Earth than the Moon, and prop
by luc4sdreyer 3y ago
> Nobody had a clue
In the 3rd century BC, Aristarchus calculated that the Sun was between 18 and 20 times farther away from the Earth than the Moon, and proposed the Heliocentric model as a result. The true value is instead approximately 400 times. But it's incredible given that he didn't have lenses, the value of Pi, and that the Geocentric model was considered correct until 1800 years after his death.
https://en.wikipedia.org/wiki/Aristarchus_of_Samos#Distance_to_the_Sun https://en.wikipedia.org/wiki/Aristarchus_of_Samos#Distance_...
Nice video about the cosmic distance ladder by Terence Tao: https://www.youtube.com/watch?v=7ne0GArfeMs https://www.youtube.com/watch?v=7ne0GArfeMs
- whimsicalism 3y agoyeah i would call estimating it as 20x when it is actually 400x firmly within “not having a clue”. He didn’t say nobody had a clue about heliocentrism.
- dexterdog 3y agoBut I believe he was the winner for many years under price is right rules.
- cwmma 3y agoPlus they didn't know the distance to the moon
- Cthulhu_ 3y agoI appreciate that he worked on it at least. Around the same era, someone else calculated the circumference of the earth (and that it was round) in a pretty accurate fashion (between −2.4% and +0.8% off) based on measuring shadows on equally sized posts at different locations on the same date. Googled, it was Eratosthenes, the cities were Alexandria and Syene/Assuan.
- ubutler 3y agoOne of my favourite episodes of Cosmos centres around Eratosthenes’ calculation of the circumference of the Earth: https://youtu.be/G8cbIWMv0rI?si=CuX49ki1GIvBLpeL https://youtu.be/G8cbIWMv0rI?si=CuX49ki1GIvBLpeL
- drexlspivey 3y agoHow did they take measurements in two different cities at the same time without clocks?
- wmanley 3y agoIIRC they walked directly north and measured at midday.
- sapiogram 3y agoHis method was fundamentally sound though. He realized that moonlight is reflected sunlight, and that if you observe the angle between the sun and the moon in the sky at exactly half moon, you can calculate the distance to the sun relative to the distance to the moon.
- Etherlord87 3y agoCan we call it an estimation if it's a range (18 to 20 times further than the Moon) and yet it is incorrect? If he said "between 2 and 1'000'000 times farther than Moon", it would be very imprecise, but not incorrect. If he said "20 times farther" - it would be an extremely inaccurate estimate.
- cryptonector 3y agoHe almost certainly knew that it was closer to 400x, but could not believe it, or did not think others would believe it. Given the size of the Earth (which he knew), that would have made the distance to and the size of the Sun something hard to stomach.