Question for the forum: What would the ancients have needed to determine planetary orbits?

First off I don't have the math(s) ability to answer this question myself so if I could call upon the many gifted posters here to answer it.

One see's claims that the ancient knew the orbits of the inner (and outer) planets.

So what instruments, mathematics and skills would be required to obtain that information? The Europeans and others seemed to have worked on this problem for centuries until they resolved it.

So having placed the question I back away and hope that those more gifted by Saint Hubertus can answer it.

a reply to: Hanslune

These would probably be useful reads:

Wikipedia: Babylonian Astronomical Diaries
Wikipedia: Hipparchus
Wikipedia: Ptolemy

I'd say a concise answer is it started with observations by ancient scholars who logged events and tracked the motions of the heavens and the understanding of celestial mechanics advanced alongside mathematics. Later prominent figures:

Wikipedia: Tycho Brahe
Wikipedia: Johannes Kepler
Wikipedia: Isaac Newton

originally posted by: Hanslune
First off I don't have the math(s) ability to answer this question myself so if I could call upon the many gifted posters here to answer it.

One see's claims that the ancient knew the orbits of the inner (and outer) planets.

So what instruments, mathematics and skills would be required to obtain that information? The Europeans and others seemed to have worked on this problem for centuries until they resolved it.

So having placed the question I back away and hope that those more gifted by Saint Hubertus can answer it.

The first thing they would need is a theory of Heliocentrism, which the certainly did not have and almost certainly could never have had, since the Sun, the Moon and planets obviously circled around the Earth.

Armed with heliocentricity, they could have established reasonable estimates of the orbits of visible planets using the same means they were using to plot their positions in the sky - good eyeballs and standard positioning equipment. They had the former, and they built the latter (stone circles, the edges of ziggurats, etc.) However, they could not have begun to do this without having the concept that these bodies orbited the Sun.

This is why Europeans had the various layers of "crystal spheres" turning around the Earth for so many years, with the planets turning little circles on their individual spheres; until moons were observed to be going around Jupiter.

Harte

most maths is pretty basic and you would know the calendar year by using a simple stone to record a point in the calendar and then count until you got the sun to the same place so it would allow you to basically define a year as number of day/night cycles and then you would notice the closer (more moving) stars so you could work out a ratio and from there i'm sure pretty much astrological can be done, it would take time to record the planets movements but its nothing that cannot be pretty much be calculated using basic physics/maths

a reply to: Hanslune

Aliens disseminating the information...

a reply to: Hanslune


That's kind of a trick question Hans,

1)By orbits do you mean an actual mathematical representation of the motion of the planet based on a limited observation?, 2)or being able to predict the passage of the planet across sky in relation to the other visible planets based on copious historic observations?, as these are two very diffent things.

 As to the first, you would have to have a basic understanding on "Newtonian" physics, which implies a mathematical understanding of geometry, algebra, trigonometry, and calculus.

 You would also need a way to record and track motion of planets as you observe them. 



Something such as a tanawah or torquetum

Tanawah

The torquetum's value, as an analogue calculator, must have been immense, because, once a planet or the Moon are not on the meridian, all "straight lines" become curves—so that calculations are difficult, even with a modern calculator. However, the 23.5-degree plane on the torquetum allows one to directly read the longitude and latitude of a planet or the Moon, relative to the ecliptic, without calculation. These data would be invaluable for predicting eclipses and occultations of various stars or planets by the Moon.

www.21stcenturysciencetech.com...

 A fascinating article, but I take the Egyptian stuff with a healthy pinch of salt.


Torquetum




 users.humboldt.edu...

The torquetum or turquet is a medieval astronomical instrument designed to take and convert measurements made in three sets of coordinates: Horizon, equatorial, and ecliptic. In a sense, the Torquetum is an analog computer.


The first torquetum is thought to have been built by Jabir ibn Aflah (Geber)[1] in the 12th century or 13th century,[2] though the only surviving examples date from the 16th century.

en.m.wikipedia.org...


 With such tools you could mathematically represent the motions of the planets.


 As to predicting their motion across the sky in some sort of cycle, first you need an observation spot. A good set of eyes, language, writing or some other symbolic way to pass information would also be helpful.

 A concept of time and how to mark it, being able determine the solstice or equinoxes.

 Then a whole lot of time spent watching them move.

 After a great deal of time you would see the patterns in the movement of the planets and be able to predict their movement.

  

a reply to: punkinworks10
I'd like to add , though the ancient Greeks could predict eclipses, and the Mayans knew the orbital period of Venus and the Egyptians observed the precession of the earth, none of these cultures knew of or could describe motions of the planets, simply for one reason, they had no understanding of gravity.

The Sumerians used to record astronomical events on hand sized clay tablets; phases of the moon, positions of the visible planets and solar eclipses. Then around 800BCE the Babylonians started analyzing this data, and derived procedures for the calculation of the Moon and other celestial objects.

en.wikipedia.org...

The Mayans recorded all the phases of the moon and other events on basement walls. Then they improved the accuracy and compiled these into the Dresden Codex.
en.wikipedia.org...

upload.wikimedia.org...

Then some simple pattern matching would reveal that full moons repeat every 28.5 days, drifting back and forth through calendar dates. Transits of Venus repeat every 243 years and eclipses follow the Saros cycle.



You can imagine a shaman being fascinated with the stars and planets, wondering how they moved, and starts creating a log book. Eventually, other people join in and eventually, all the notes are compiled into a single document.

a reply to: punkinworks10

Thanks for the detailed and informative post - and sorry no 'trick' intended!

a reply to: stormcell

Especially if they thought these motions were messages or signs from the Gods and from them they could derive 'magical' powers or information of use to them on 'earth'.

originally posted by: punkinworks10
a reply to: punkinworks10
I'd like to add , though the ancient Greeks could predict eclipses, and the Mayans knew the orbital period of Venus and the Egyptians observed the precession of the earth, none of these cultures knew of or could describe motions of the planets, simply for one reason, they had no understanding of gravity.

So are you saying that unless a culture had an understanding of gravity they would not be able to ascertain / work out the orbit of a planet?

a reply to: Hanslune
Yes, I am saying that.

They could work out it's orbital period , that's just basic observation, it's relationships to other orbital periods and cyclic celestial phenomena.
They couldn't tell you how far away it is, how fast it's moving ir how it's movemnt through space is affected by the other objects in space or how it's motion is fixed about some point of reference.
As was previously mentioned, you have to accept a basic helio centric view, which is illustrating gravitational effects.

a reply to: Hanslune

No math or instruments just a memory of creation itself. What we seem to be trying to do is reverse engineer the system and they were probaly just explaining what they had witnessed.

originally posted by: deadeyedick
a reply to: Hanslune

No math or instruments just a memory of creation itself. What we seem to be trying to do is reverse engineer the system and they were probaly just explaining what they had witnessed.

Ah who witnessed what?

a reply to: Hanslune
as above so below perhaps the watchers?lol
it would be the same as watching your neighbor build a house.
I will definitly in explaination due to yrs of programming we went through recently.
Let's say you were a helper for a swiss watch maker and decided to write down the process. You would be very accurate but let's say that today someone just out of school decided to open up a swiss watch and then tried to explain how it works from scratch.

originally posted by: deadeyedick
as above so below perhaps the watchers?lol
it would be the same as watching your neighbor build a house.
I will definitly in explaination due to yrs of programming we went through recently.
Let's say you were a helper for a swiss watch maker and decided to write down the process. You would be very accurate but let's say that today someone just out of school decided to open up a swiss watch and then tried to explain how it works from scratch.

Sorry dude no idea what you are talking about. What do Swiss watch makers have to do with what the ancients would have needed to know to work out planetary orbits???

a reply to: Hanslune

They both represent the knowledge of motions with respect to other motions, within a frame of reference.
Ultimately the art of the watch maker is a direct descendant of the Antykathera mechanism, which is constructed to represent the motions of the planet's and moon to each other.

I find it very akward that some people are starting to understand me sometimes nowdays.

a reply to: Hanslune

Too bad the majority of Pythagoras' work was destroyed.

"There's music int he spheres"

How far would you go, with this instrument as technological advanced possible. Incorrect theories account for the imperfections of the mechanism.
At this point the Greek where already aware that the Sun was going around the Earth right ? Or isn't this obvious for people able to calculate the stuff in the instrument, and more or less the diameter of the Earth from the difference of a shadow created by the Sun between to wells 900 miles apart or something... Surprisingly close to the current answer.

Sorry I've gotta read up on that Helio centrinism thing yet...

Antykathera mechanism

Accuracy[edit]
Investigations by Freeth and Jones[31] reveal that their simulated mechanism is not particularly accurate, the Mars pointer being up to 38° off at times. This is not due to inaccuracies in gearing ratios or such in the mechanism, but rather to inadequacies in the Greek theory at that point in time. This could not have been improved until first Ptolemy introduced the equant in about 150 AD, and then when Johannes Kepler changed orbits to ellipses and broke from the concept of uniform motion and circular orbits in 1609 AD.

In short, the Antikythera Mechanism was a machine designed to predict celestial phenomena according to the sophisticated astronomical theories current in its day, the sole witness to a lost history of brilliant engineering, a conception of pure genius, one of the great wonders of the ancient world—but it didn’t really work very well!

In addition to theoretical accuracy, there is the matter of mechanical accuracy. Freeth and Jones note that the inevitable "looseness" in the mechanism due to the hand-built gears with their triangular teeth and the frictions between gears and in bearing surfaces would have probably swamped the finer solar and lunar correction mechanisms built into it:

Though the engineering was remarkable for its era, recent research indicates that its design conception exceeded the engineering precision of its manufacture by a wide margin—with considerable accumulative inaccuracies in the gear trains, which would have cancelled out many of the subtle anomaly corrections built into its design.

Bumping the the first step to a pc... too. Plug in Bagdhad battery and you would have had less wear and tear. My brain sometimes sucks me into these silly things, which I can still do with my unlimited lay men's boundaries