SDTV and high definition television (HDTV) are the two categories of display formats for digital television (DTV) transmissions, which are becoming the standard. In North America, digital SDTV is broadcast in the same 4:3 aspect ratio as NTSC signals with widescreen content being center cut.
Command pilot Neil Armstrong 's flight marked the second time a U.S. civilian flew into space (Joseph Albert Walker became the first U.S. civilian on X-15 Flight 90). Armstrong had resigned his commission in the United States Naval Reserve in 1960.
Student Features. Thirty-five years ago astronaut Neil Armstrong did something no one had ever done before. On July 20, 1969, he set foot on the moon. People around the world watched and listened as Neil slowly climbed down the ladder of the lunar lander.