What is the Analemma?
The Analemma is an unequal figure-of-eight shape, created by tracking the sun’s position in the sky at the same time each day over a period of one year.
Image: courtesy S.D. Smith.
This graphic shows the path of the sun captured at 2pm each day for the period of one year. The vertical axis shows angle up from the horizon with 90 degrees at the top being right above your head. The horizontal axis shows that the sun appears in the south south west at this time of day in Dundee.
Why do we see an unequal figure of eight?
- The earth is tilted at 23°
- Earth’s orbit is an ellipse
- The orbital speed changes
Johannes Kepler was one of the most important scientists who discovered the three laws of planetary motion. These describe the elliptical path all planets follow as they orbit around a star such as in our solar system.
You can see an image of Kepler’s 2nd Law cast in the bronze sundial sculpture. The sun shape on the other side of the bronze alludes to our sun-centred solar system.
The monthly shadows cast by the sun have been marked into the landscape, giving the analemma shape, inverted because it is the sun’s shadows that are cast here, shown in the image below. It helps us to understand the importance of the sun’s influence on seasons and for life on this planet here in Dundee.
Visible in the stone plinth is a timeline of scientists from history who have contributed to the development of Astronomy. Each scientist has built upon the knowledge and discoveries of those who have gone before.
