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Spirit’s dimming Sun (sols 1220-1305)

Spirit’s dimming Sun (sols 1220-1305)
Spirit’s dimming Sun (sols 1220-1305) Several times a sol, the Mars Exploration Rovers take images of the Sun (using a very dark solar filter) to determine the opacity of the atmosphere (a property that is referred to as "tau"). Here, images of the sun taken since sol 1220 of Spirit's mission have been calibrated to show how dim the Sun appeared through the dust storm. Wherever a circle with an "X" appears, for example, for sols 1263-1265 (July 23-25, 2007), the skies were so dark that Spirit could not muster enough power to perform its usual tau measurements. NASA / JPL-Caltech / Cornell / Emily Lakdawalla