The Sun’s Analemma

The Sun’s Analemma The yellow line that resembles a “figure eight“ is called an analemma. It traces the continuous path of the Sun over the period of one year. The analemmas unique shape is the result of two unique properties of the Earth: The Earth’s axis of rotation is tilted 23.5º relative to the plane of the ecliptic. This tilt results in a perceived up and down (vertical) motion of the Sun when viewed from Earth. The shape of the Earth’s orbit is elliptical, and this causes the rate at which the Earth orbits the Sun to vary. The left and right motion (the distance from a vertical centerline) is the result of this changing rate. If the Earth’s orbit was perfectly circular, the analemma would become a vertical line. Further, if there were no tilt in the axis of the Earth relative to the plane of the ecliptic (and the Earth had a circular orbit), the Sun’s position would not change in this tour — it would appear in the same location each day