Real-time solar observations

A system for real-time solar observation, the system comprising:

• an optical detector operable to detect sunlight and to produce image data from detected sunlight, wherein the optical detector is operable to provide sunrise image data from a substantially East-facing direction, and to provide sunset image data from a substantially West-facing direction;
• a shadow detector operable to produce image data relating to a shadow cast by a reference object;
• and
• a controller operable to receive image data from the optical detector and from the shadow detector, wherein the controller is operable to:
• determine at least one of a sunrise period, a midday period and a sunset period in dependence upon the received image data,
• detect the sunrise period by detecting a sunrise period start time at which substantially white light is first visible parallel above a predetermined horizon, and by detecting a sunrise period end time at which a solar disc image is substantially tangential with the predetermined horizon,
• detect the midday period by detecting a midday period start time at which said shadow has a minimum length, and by detecting a midday period end time at which said shadow has a length substantially equal the sum of the minimum length and the length of the reference obiect, and
• detect the sunset period by detecting a sunset start time at which a solar disc image is substantially tangential above the predetermined horizon, and by detecting a sunset end time at which no substantially red light is visible above the predetermined horizon.