A Sun outage is an interruotion in or distortion of geostationary satellite signals caused by interference from solar radiation.The effect is due to the sun's radiation overwhelming the satellite signal.At these times,the apparent path of the sun across the sky takes it directly behind the line of sight between an earth station and a satellite .As the sun radiates strongly at the microwave frequencies used to communicate with satellite ( c band and k band),the sun swaps the signal from the satellite.The effect of a sunoutage can include partial degration,that is an increse in the error rate,or total destruction of the signal.

In India the BSE and NSE use VSATs ( Very Small Aperture Terminal)for members to connect to their trading system.VSATs depend upon satellites for connectivity between the terminals.Hence these exchanges are affected due to the sun outage. So exchanges normally remain closed from 11:45 to 12:30 deu to sun outage for some week.This times vary depending on the scientific factor.