... Day З In common usage the word "day" unfortunately has two different meanings: (1) the period of time when the Sun is up (what we have been calling "daytime") (2) the period of time between consecutive sunrises (or sunsets), or one daytime + one nighttime. ... The sky turns dramatically dark and bright stars and planets can be seen. ... З The planets move roughly along the same path as the Sun and Moon. ... The Moon took a month to circle the sky, the Sun a year, each planet its own period of time. ...

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• http://www.aaa.org/EyepieceFiles/aaa/2010_04_April_Eyepiece.pdf

... THE 'VON OPEL FLIGHTS' . ... Raab, with his partner Diploma Engineer Kurt Katzenstein would apply to their lightest aeroplane the solid-propellant Sander rockets that had proven themselves so well in Fritz von Opel's rocket cars. ... The von Opel-Sander-Stamer-Lippisch tests were elevated to a full-scale airplane immediately after the model flights ; in effect, this was to be the first manned rocket flight. ... FRITZ VON OPEL at the controls of the Opel Sander Rak. 1 rocket plane. ...