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Wikipedia puts discovery of the first six planets under 'prehistoric.' https://en.m.wikipedia.org/wiki/Timeline_of_discovery_of_Solar_System_planets_and_their_

Wikipedia puts discovery of the first six planets under 'prehistoric.' https://en.m.wikipedia.org/wiki/Timeline_of_discovery_of_Solar_System_planets_and_their_moons https://en.m.wikipedia.org/wiki/Timeline_of_discovery_of_Sol...

macksd 5y ago
I thought we weren't able to chart their orbits and thus know their orderings until the last few centuries. I'm sure we recognized them as being brighter than stars, visible as more than points of light, with non-sidereal motion, and we gave them names. But I don't think we knew Saturn was 6th "prehistorically".
- sdenton4 5y ago
  Here's some more fun reading: https://en.m.wikipedia.org/wiki/Aristarchus_of_Samos https://en.m.wikipedia.org/wiki/Aristarchus_of_Samos "... an ancient Greek astronomer and mathematician who presented the first known heliocentric model that placed the Sun at the center of the known universe, with the Earth revolving around the Sun once a year and rotating about its axis once a day. He was influenced by the concept presented by Philolaus of Croton (c. 470 – 385 BC) of a fire at the center of the universe, but Aristarchus identified the "central fire" with the Sun and he put the other planets in their correct order of distance around the Sun.[2]" The ancients were smarter than we think, usually.
- irrational 5y ago
  Wouldn’t they be able to know/guess based on the fact that it took longer to orbit the sun than Jupiter?
thaumasiotes 5y ago
> Wikipedia puts discovery of the first six planets under 'prehistoric.' Wikipedia is counting the Earth as a planet.
adrian_b 5y ago
In that Wikipedia article, "prehistorically" is improperly used. "Prehistoric" means before the appearance of written records, which means before the 3rd millenium BC (when there are many Egyptian and Sumerian/Akkadian written records). There is no evidence that the planets (i.e. excluding the Sun, Earth and Moon) were known prehistorically. The evidence is actually that 4 planets, Mercury, Mars, Jupiter and Saturn, have been discovered, as correctly written in the Wikipedia article, only in the 2nd millennium BC, in Babylonia. That is a historical time not prehistorical. The only planet known in prehistory was Venus, because it is much brighter than any star, so its movement on the sky is obvious, but it was known as 2 distinct stars, the Morning Star and the Evening Star. Only very late it became understood that there is actually a unique celestial body that appears in 2 forms. This discovery was made in Sumer, probably in the 3rd millenium BC, or maybe as early as the 4th millenium BC. (This Sumerian discovery is reflected in the legend of Inanna, who descends in the underworld, then she returns to the heavens, like the Evening Star disappears and then returns as the Morning Star). This knowledge has propagated to other places only very slowly. For example Homer mentions some stars and constellations and also both the Morning Star and the Evening Star, but there is not the slightest hint that he or the other Greeks of the 8th century BC might have known that those 2 "stars" are in fact the same body.
- sdenton4 5y ago
  Yeah, the use of 'prehistory' seems not great in this context; there's a fundamental problem of how we would know which bodies were known prior to the existence of a writing system. But there are a number of things that make these very discoverable: They are visible with the naked eye, all lie in the ecliptic plane, and behave a bit strangely if you watch them over time. Mars is a bit red, and absolutely stands out... And of course Venus can't be ignored. Once you've noticed Venus and Mars, finding the others is a matter of looking a bit harder. Using stars for navigation or for measuring the passage of time involves observing them consistently, which leads one to notice 'odd' things. So I wouldn't at all be surprised if the planets were known in, say, prehistoric Polynesian cultures... The appearance of mathematical astronomy in Babylonia tells us that the movement of celestial bodies is approximately the first scientific knowledge a civilization will bother to write down. https://en.wikipedia.org/wiki/Babylonian_astronomy#Old_Babylonian_astronomy https://en.wikipedia.org/wiki/Babylonian_astronomy#Old_Babyl...

macksd 5y ago

I thought we weren't able to chart their orbits and thus know their orderings until the last few centuries. I'm sure we recognized them as being brighter than stars, visible as more than points of light, with non-sidereal motion, and we gave them names. But I don't think we knew Saturn was 6th "prehistorically".

sdenton4 5y ago
Here's some more fun reading: https://en.m.wikipedia.org/wiki/Aristarchus_of_Samos https://en.m.wikipedia.org/wiki/Aristarchus_of_Samos "... an ancient Greek astronomer and mathematician who presented the first known heliocentric model that placed the Sun at the center of the known universe, with the Earth revolving around the Sun once a year and rotating about its axis once a day. He was influenced by the concept presented by Philolaus of Croton (c. 470 – 385 BC) of a fire at the center of the universe, but Aristarchus identified the "central fire" with the Sun and he put the other planets in their correct order of distance around the Sun.[2]" The ancients were smarter than we think, usually.
irrational 5y ago
Wouldn’t they be able to know/guess based on the fact that it took longer to orbit the sun than Jupiter?

thaumasiotes 5y ago

> Wikipedia puts discovery of the first six planets under 'prehistoric.' Wikipedia is counting the Earth as a planet.

adrian_b 5y ago

In that Wikipedia article, "prehistorically" is improperly used. "Prehistoric" means before the appearance of written records, which means before the 3rd millenium BC (when there are many Egyptian and Sumerian/Akkadian written records). There is no evidence that the planets (i.e. excluding the Sun, Earth and Moon) were known prehistorically. The evidence is actually that 4 planets, Mercury, Mars, Jupiter and Saturn, have been discovered, as correctly written in the Wikipedia article, only in the 2nd millennium BC, in Babylonia. That is a historical time not prehistorical. The only planet known in prehistory was Venus, because it is much brighter than any star, so its movement on the sky is obvious, but it was known as 2 distinct stars, the Morning Star and the Evening Star. Only very late it became understood that there is actually a unique celestial body that appears in 2 forms. This discovery was made in Sumer, probably in the 3rd millenium BC, or maybe as early as the 4th millenium BC. (This Sumerian discovery is reflected in the legend of Inanna, who descends in the underworld, then she returns to the heavens, like the Evening Star disappears and then returns as the Morning Star). This knowledge has propagated to other places only very slowly. For example Homer mentions some stars and constellations and also both the Morning Star and the Evening Star, but there is not the slightest hint that he or the other Greeks of the 8th century BC might have known that those 2 "stars" are in fact the same body.

sdenton4 5y ago
Yeah, the use of 'prehistory' seems not great in this context; there's a fundamental problem of how we would know which bodies were known prior to the existence of a writing system. But there are a number of things that make these very discoverable: They are visible with the naked eye, all lie in the ecliptic plane, and behave a bit strangely if you watch them over time. Mars is a bit red, and absolutely stands out... And of course Venus can't be ignored. Once you've noticed Venus and Mars, finding the others is a matter of looking a bit harder. Using stars for navigation or for measuring the passage of time involves observing them consistently, which leads one to notice 'odd' things. So I wouldn't at all be surprised if the planets were known in, say, prehistoric Polynesian cultures... The appearance of mathematical astronomy in Babylonia tells us that the movement of celestial bodies is approximately the first scientific knowledge a civilization will bother to write down. https://en.wikipedia.org/wiki/Babylonian_astronomy#Old_Babylonian_astronomy https://en.wikipedia.org/wiki/Babylonian_astronomy#Old_Babyl...