Research on Red Stars in
the Hipparcos
The Tychonic Model
The graphic above comes from Astronomia Danica, Longomontanus’ book published in 1640.
Longomontanus basically expounded on Brahe’s model in A.D. He kept Tycho’s arrangement which differed from all the other models in the fact that the Sun and Mars’ orbit crossed one another.
Tycho’s model did not have a diurnal motion for Earth, i.e. it did not spin. Longomontanus’ updated Tychonic model did have the Earth spinning on its axis. In both versions, Earth was stationary at the center of the solar system. Both men were heavily influenced by the Bible.
Brahe’s arrangement featured the Sun revolving around the Earth/Moon while Venus and Mercury revolved around the Sun. So in that aspect, Mercury and Venus are heliocentric, well in actuality, so are Mars, Jupiter and Saturn. All of the planets, except the Earth, orbit the Sun in the Tychonic model.
Object
It is my goal to translate Astronomia Danica from Latin into English. Something that should have already been done a long time ago.
As I go along thru the book I will point out the reasons why I find their observations to be accurate and show how these determinations were made at the time as best I can.
Ptolemy’s Sun Angle Finder
Full disclosure, I came upon this instrument at the Following Kepler blog. He made one from scratch and I thought that I might be able to improve on his a bit.
It’s a nightmare cutting a circle out of metal unless you have some specific equipment that I do not. These days however, there are a multitude of online businesses that will do just that for you. After looking at several I chose SendCutSend because they have an app that you can basically draw the piece with online. They offer many different metals and other materials. I was originally looking at brass but its expensive, so I opted for 3/16” aluminum for $91.
The pieces arrived within a week and they are just about dead on the money dimensionally. I think they used a laser to do the cutting. They have an upgrade where you can have them deburr the part which I opted not to do. It only took me a few minutes with a file and sandpaper and I had the two pieces fitting together quite nicely.
After a couple of attempts to put the tick marks on the outer ring using a protractor a better idea dawned on me. I laid it out in Autocad and printed it and then taped that down to the ring. Then I put the tick marks in using a chisel. That worked out well.
I have the pieces of the dial on temporarily with double sided tape. They are just pieces of wood. When I have figured out exactly how I want it to be I will put some metal parts on permanently with screws.
Test Run
I have it temporarily mounted to a post and I tried it out this morning. I was going by a latitude that’s a bit south of here but it was reading fairly close. The pic below shows the angle at about 8:40 a.m. that should have been about 43° and this was right on 40°. Not plumbed and I am actually a bit north of that city’s latitude I was going by.
I need to figure out how the size and shape of the “pointer” affects things. I do not think the rear pointer is even necessary other than helping to hold the plates together. I will probably add a plumb line to it as well.
Real World/Sphere World
Even something this simple shows that Earth is spherical. You could go either north or south a couple of hours and at the same time of the day the reading would change due to the latitude. It should read precisely the same if you went east or west as long as the local time was the same.
So in theory you could have a dozen of these at various places around your region and then at given times write down the reading and then compare notes later on. You would then be able to deduce a) Earth is spherical and b) the size of the sphere I’m pretty sure.
Longomontanus.net
Welcome to the home of all things Christian Sorensen, aka Longomontanus!
From this moment forward everything that I learn from the translation of Astronomia Danica from Latin will find its home here.
Longomontanus was Tycho Brahe’s most trusted and long lived assistant at Uraniborg, were he observed for over ten years.