Solar Synoptic Map Building

A synoptic map shows a large portion of the surface of the Sun. From an observatory on Earth or in Earth orbit we can see only one side of the Sun at any one time. The Sun rotates fully about every 27 days, so over time we can see the whole surface. To make a synoptic map, over 100 images of the Sun are taken at six-hour intervals during the course of one rotation. Longitudinal strips are taken from the center of each image and placed side-by-side in sequence to create a composite image that shows almost the entire Sun.

The surface of the Sun is dynamic. From one period of six hours to the next the Sun changes only a little, so the transition between consecutive strips appears very smooth. However, the time difference between the first and last strip is more than 27 days, during which noticeable changes occur. This causes a visible discontinuity where the two ends of the map come together. The fact that the surface of the Sun rotates at slightly different rates at different latitudes adds to this discontinuity.

The north and south poles of the Sun are not well represented in this kind of map. Furthermore, due to a 7 degree tilt of Earth's orbit with respect to the Sun’s rotational axis, one of the Sun's poles is often not seen at all during a rotation.

The synoptic map on SOS shows the Sun from 10/1/2023 to 10/27/2023. The images are from the Atmospheric Imaging Assembly (AIA) of the Solar Dynamics observatory (SDO) which is in a geosynchronous Earth orbit. The images are made using ultraviolet light (30.4nm wavelength) which shows activity and detail in the solar chromosphere.

Length of dataset: 0:36