Touching down on this day in 1976, the seventh anniversary of the Apollo 11 Moon landing, Viking 1 became the second probe to successfully reach Mars after the Soviet Union’s Марс-3 five years earlier—beginning what would turn out to be a rather incredible six-year monitoring mission (sadly, the previous effort failed after seconds) with a battery of biological experiments to search for evidence of life.
Scientists were also able to use this distant beacon that’s sometimes occulted by the Sun to confirm the phenomenon of gravitational time dilation as predicted by the theory of General Relativity, the Sun’s gravity causing delays in transmission times. The Viking sent back this incredible panoramic vista (landing site in the title) shortly after its arrival.