This affects the actual length of a day, as the earth does not always spin at the same speed. Moreover it tilts slightly on it’s axis in different quasi periodic patterns. The tilting motion is termed precession and nutation, with several overlapping periods of motion. Some periods correspond approximately to a year, (some also less), longer period can be seen over e.g. 18 years, and there is a grand period of tilting happening over approximately 26.000 years.


Earth Orientation Parameters


We normally tend to think of our globe as a solid chunc of rock. This is not so. You could say it is more like a ball of jelly. It is commonly known that we have water tides, where the oceans is being pulled by the gravity of the moon. What is less commonly known is that we have earth tides, with the actual crust of the earth moving up and down in synchrony with the water tides. These and other forces work on the earth and makes it stretch and contract. This affects the spin of the earth. Like a ballet dancer or ice skater doing pirouettes, when keeping the limbs close to the body, the rotational speed goes up. Similarly, when the extremities are more loosely held, the rotational speed goes down.


In the installation we can hear this earth orientation parameter mapped to a synthesized singing voice. I tend to think of it like a lonely mother earth singing her uneven motion through space.