What was the first man made signal to leave earth, and how far has it traveled by now?
The first intentional wireless transmission of a signal was most likely done in an experiment performed by David Edward Hughes around 1880. Some of that energy might have left the earth (however, the Ionosphere do block some signals, we are not sure whether or not that transmission really could have made it out to space), and if so have been traveling through space ever since, some 132 years or so. As it turns out, radio signals travel with the speed of light, so it will have traveled 132 light years by now, or about 30 parsecs. That’s 1.2298 x 1015 kilometers, or 7.6420 × 1014 miles. Or about 30.68 billion times around the equator. Sounds like a lot, but our galaxy is a whopping 100,000 to 120,000 light years in diameter. However, the signal will have passed a lot of stars already, many which are known to have planets, such as Gliese 674, Gliese 832 and Gliese 876. It passed Sirius, the brightest star in the sky, only about eight and a half year after being transmitted.
The first radio broadcast that was intended to be sent to extraterrestrial civilizations was transmitted on November 19, 1962 by a Soviet planetary radar. The transmitted message was “MIR” (means “peace” and “world”), “LENIN” and “SSSR” (Acronym for the Soviet Union). This message is commonly referred to as The Morse Message. Having traveled for a little more than 51 years, which means it has traveled little more than 51 light years or 4.8248 x 1014 km, it will have traveled past the stars we mentioned in the first paragraph.
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