The traditional story is that in olden times people were proudly stupid and thought the human animal lived at the centre of the universe, with all the planets, stars and the sun revolving around the God’s creation, made in his image. The church would send anybody that said the sun was at the centre to be burned at the stake. [1]
Except...
there is no absolute sense in which the sun is at the centre of the solar system [2]. It’s simply a question of perspective, a choice of frame of reference.
Geocentrism is empirically grounded: it is literally what you see! Your lieing eyes, the cold hard facts and 16th century Mathew Barnett all agree: geocentrism is right.
The heliocentric point of view is a formal transformation of the data—a transformation with potentially heretical implications, a dangerous figment of the imagination …
The Ptolemaic model fits the data well. It’s based on elegant principles of iterated circles (epicycles). The heliocentrists love to talk about how their model is more mathematically elegant but they haven’t made a single prediction that the Ptolemaic model hasn’t. The orbits of planets become ellipses which have more free variables than the astrally perfect circles.
“Venus in retrograde” nowadays evokes images of a cartoon gypsy woman hand reading but it is a real astronomical phenomenon that mystified early stargazers wherein Venus literally moves backward some of the time. In the Ptolemaic model this is explained by a small orbit (cycle) on a large orbit (cycle) going backward. In the heliocentric model it is a result of the earth moving around the sun rather than vice versa that causes the apparent backwards motion of Venus.
3. Epicycles can be computed FAST. For epicycles are the precarnation of GEARS. Gears, which are epicycles manifest.
How does the Antikythera mechanism work? It is a Ptolemaic-esque model where the epicycles are literally modelled by gears! In other words—the choice for epicycles wasn’t some dogmatic adherence to the perfection of the circle, it was a pragmatic and clever engineering insight!
[1] Contra received history, the Catholic Church was relatively tolerant of astronomical speculation and financially supported a number of (competent) astronomers. It was only when Giordano Bruno made the obvious inference that if the planets revolve around the sun, sun are other starts then… there might be other planets, with their own inhabitatns… did Jesus visit all the alien children too ?… that a line was crossed. Mr Bruno was burned at the stake.
[2] centre of mass not the sun. but the centre of mass is in the sun so this is a minor pedantry.
I think it’s pretty good to keep it in mind that heliocentrism is literally speaking just a change in what coordinate system you use, but it is legitimately a much more convenient coordinate system.
For everyday life, flat earth is more convenient than round earth geocentrism, which in turn is more convenient than heliocentrism. Like we don’t constantly change our city maps based on the time of year, for instance, which we would have to do if we used a truly heliocentric coordinate system as the positions of city buildings are not even approximately constant within such a coordinate system.
This is mainly because the sun and the earth are powerful enough to handle heliocentrism for you, e.g. the earth pulls you and the cities towards the earth so you don’t have to put effort into staying on it.
The sun and the planetary motion does remain the most important governing factor for predicting activities on earth, though, even given this coordinate change. We just mix them together into ~epicyclic variables like “day”/”night” and “summer”/”autumn”/”winter”/”spring” rather than talking explicitly about the sun, the earth, and their relative positions.
Since you’re already in it: do you happen to know if the popular system of epicycles accurately represented the (relative, per body) distance of each planet from earth over time, or just the angle? I’ve been curious about this for a while but haven’t had time to dig in. They’d at minimum have to get it right for the moon and sun for predicting eclipse type.
The Sun revolves around the Earth actually
The traditional story is that in olden times people were proudly stupid and thought the human animal lived at the centre of the universe, with all the planets, stars and the sun revolving around the God’s creation, made in his image. The church would send anybody that said the sun was at the centre to be burned at the stake. [1]
Except...
there is no absolute sense in which the sun is at the centre of the solar system [2]. It’s simply a question of perspective, a choice of frame of reference.
Geocentrism is empirically grounded: it is literally what you see! Your lieing eyes, the cold hard facts and 16th century Mathew Barnett all agree: geocentrism is right.
The heliocentric point of view is a formal transformation of the data—a transformation with potentially heretical implications, a dangerous figment of the imagination …
The Ptolemaic model fits the data well. It’s based on elegant principles of iterated circles (epicycles). The heliocentrists love to talk about how their model is more mathematically elegant but they haven’t made a single prediction that the Ptolemaic model hasn’t. The orbits of planets become ellipses which have more free variables than the astrally perfect circles.
2. Epicycles is Fourier analysis. No really!
“Venus in retrograde” nowadays evokes images of a cartoon gypsy woman hand reading but it is a real astronomical phenomenon that mystified early stargazers wherein Venus literally moves backward some of the time. In the Ptolemaic model this is explained by a small orbit (cycle) on a large orbit (cycle) going backward. In the heliocentric model it is a result of the earth moving around the sun rather than vice versa that causes the apparent backwards motion of Venus.
3. Epicycles can be computed FAST. For epicycles are the precarnation of GEARS. Gears, which are epicycles manifest.
Late Hellenistic age possibly had a level of science and engineering only reached in late 17th century Western Europe, almost 2000 years later. The most spectacular example of Hellenistic science is the Antikythera mechanism, a blob of bronze rust found by divers off the Greek Coast. X-ray imaging revealed a hidden mysterious mechanism, launching a many-decade sleuthhunt for the answer. The final puzzle pieces were put together only very recently.
How does the Antikythera mechanism work? It is a Ptolemaic-esque model where the epicycles are literally modelled by gears! In other words—the choice for epicycles wasn’t some dogmatic adherence to the perfection of the circle, it was a pragmatic and clever engineering insight!
[1] Contra received history, the Catholic Church was relatively tolerant of astronomical speculation and financially supported a number of (competent) astronomers. It was only when Giordano Bruno made the obvious inference that if the planets revolve around the sun, sun are other starts then… there might be other planets, with their own inhabitatns… did Jesus visit all the alien children too ?… that a line was crossed. Mr Bruno was burned at the stake.
[2] centre of mass not the sun. but the centre of mass is in the sun so this is a minor pedantry.
I think it’s pretty good to keep it in mind that heliocentrism is literally speaking just a change in what coordinate system you use, but it is legitimately a much more convenient coordinate system.
For everyday life, flat earth is more convenient than round earth geocentrism, which in turn is more convenient than heliocentrism. Like we don’t constantly change our city maps based on the time of year, for instance, which we would have to do if we used a truly heliocentric coordinate system as the positions of city buildings are not even approximately constant within such a coordinate system.
This is mainly because the sun and the earth are powerful enough to handle heliocentrism for you, e.g. the earth pulls you and the cities towards the earth so you don’t have to put effort into staying on it.
The sun and the planetary motion does remain the most important governing factor for predicting activities on earth, though, even given this coordinate change. We just mix them together into ~epicyclic variables like “day”/”night” and “summer”/”autumn”/”winter”/”spring” rather than talking explicitly about the sun, the earth, and their relative positions.
Since you’re already in it: do you happen to know if the popular system of epicycles accurately represented the (relative, per body) distance of each planet from earth over time, or just the angle? I’ve been curious about this for a while but haven’t had time to dig in. They’d at minimum have to get it right for the moon and sun for predicting eclipse type.