January 7

1610: Galileo Galilei sighted four of Jupiter's moons (Io, Europa, Ganymede, and Callisto). 1785: Jean Blanchard and John Jeffries made first air crossing of the English Channel from England to France in a hot-air balloon (first international flight). 1904: Marconi established "CQD" (-·-· --·- -··, CQ=be quite and listen, D=distress) as the first international radio distress signal, but two years later, "SOS" (··· --- ···, Save Our Souls) became the radio distress signal because it was faster to send by wireless radio. 1927: Commercial transatlantic telephone service was inaugurated between New York and London. 1935: Sir Alfred Ewing, the physicist who discovered and named hysteresis, died. 1943: Serbian-American high voltage experimenter Nikola Tesla died. 1980: The first solar-cell power plant  was dedicated at Natural Bridges National Monument, UT (266,029 solar cells in 12 producing 100 kW). 1998: Richard Hamming, of error correction code fame, died. 2004: American electrical engineer Oswald "Mike" Villard Jr., who developed over-the-horizon radar, died.