jan 1, 500 - Angular size of Mars and its distance to Earth
Description:
The Indian astronomical text "Surya Siddhanta" - the oldest astronomy book ever known -
estimated the angular size of Mars as 2 arc-minutes (1/30 of a degree) and its distance to Earth as 10,433,000 km. From this the diameter of Mars is deduced to be 6,070 km, which has an error within 11% of the currently accepted value of 6,788 km.
Added to timeline:
Timeline of Mars Observation and Exploration
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