The German National Museum has a unique collection of astrolabies.

We have the largest collection of these devices in the German language, 13 in total.

Some of them come from the early times of the astrolabe, from the 11th and up to the 13th century,

when such instruments were still in the Arabian cultural space, in the Muslim cultural space.

A second collection is documented by the so-called Vienna School of Astronomy,

where the famous mathematician Johannes Regio Montanus collects the anus,

which we have some astrolabias from. And finally, from the later times of the astrolabias,

here we have an example of this, opulent astrolabias of the Mangerismus,

the height of the Renaissance, of the Renaissance art work.

This piece is first of all drawn by its sheer size, as you can see.

It is worked on the most elaborate way possible by a mathematician,

Johannes Pretorius, for the collection of scientific instruments of a Nuremberg doctor.

In the 1560s, Mönchio Eierer has added a number of such instruments,

on the one hand to represent how he is educated, how he is educated,

because he is the master of these instruments and their use.

On the other hand, Eierer has certainly also made scientific observations

of the astronomical species with this astrolabias.

For us, the Erlanger project is of course a welcome occasion.

We can also expand our knowledge about our astrolabias

and are very happy about this collaboration.

We have here a wonderful astrolabe.

If in the Middle Ages I were holding an instrument like this with my hands,

I could say that I was holding the wall in my hands.

This statement was neither a metaphor nor an exaggeration,

because an astrolabe was an accurate and fair image of the sky,

as it was seen from a specific place on the Earth,

which was the latitude or the climate for which the astrolabe was made.

It has remained functional until nowadays, despite the Copernican Revolution,

and the establishment of the heliocentrism in the 16th century.

The reason is that anyone who observes the sky is doing it from a specific place on the Earth

and ultimately from the Earth itself.

This situation makes any observation and calculation performed with an astrolabe

in the 21st century as geocentric as it was, let's say, in the 12th or the 11th century.

This astrolabe and any astrolabe consist of different components and two parts.

The components are the matter, which is literally the mother,

because it contains everything inside,

the rette, which is on top,

the alidate, which is always on the back and is the sighting tool,

the pin and the horse, which are just in the centre and keep all the components together,

and the latitude plate, which is placed below the rette

and inside the matter.

The two parts are the heavenly part, which is represented mostly by the rette,

and the Earth, which is a specific horizon, which is projected on the latitude plate

and works for a specific latitude.

The rette is a projection of the heaven and displays several stars with the pointers.

We can see here, this is one pointer, one star is laying here, one star here, other.

All these are pointers of stars.

It also displays the ecliptic or zodiac, which is the solar path, this one,

and we can read the names of the zodiac signs,

the axis and also the axis of the equinoxes, which here is, let me see, here, this one.