On February 10, 1958, scientists at MIT's Lincoln Laboratory bounced radar waves off of Venus.
At the time, Venus was at a point in its orbit called inferior conjunction, where it is directly in between the Earth and the sun. Scientists beamed a radar signal toward Venus, which was about 28 million miles away at the time. It took about 5 minutes for the signal to bounce off of Venus and return to Earth. This was slightly shorter than they anticipated, which means that Venus was actually closer to Earth than scientists believed at the time.
