(13) http://commons.wikimedia.org/wiki/Image:750.JPG. Public Domain.
(14) http://en.wikipedia.org/wiki/Image:Salyut_7_from_Soyuz_T-13.jpg.
GNU-FDL.
(15) http://en.wikipedia.org/wiki/Image:Sts_mprof.jpg. Public Domain.
(16) NASA.http://history.nasa.gov/sputnik/sputnik1.jpg. Public Domain.
(17) http://en.wikipedia.org/wiki/Image:V-2_Rocket_On_Meillerwagen.jpg. Public
Domain.
(18) http://spaceflight.nasa.gov/gallery/images/station/assembly/html/
s117e08045.html. Public Domain.
(19) http://en.wikipedia.org/wiki/Image:EM_spectrum.svg. GNU-FDL.
(20) http://en.wikipedia.org/wiki/File:
Yerkes_40_inch_Refractor_Telescope-1897.jpg. Public Domain,.
(21) http://commons.wikimedia.org/wiki/Image:Salt_mirror.jpg. Public Domain.
(22) http://en.wikipedia.org/wiki/File:
Yerkes_40_inch_Refractor_Telescope-2006.jpg. Public Domain.
(23) http://hubblesite.org/newscenter/archive/releases/2004/27/image/a. Public
Domain.
(24) Public Domain.http://commons.wikimedia.org/wiki/Image:Galileos_Moon.jpg.
(25) http://en.wikipedia.org/wiki/Image:Newton_Cannon.svg. GNU-FDL.
(26) NASA. http://en.wikipedia.org,http://en.wikipedia.org/wiki/File:
Spitzer-_Telescopio.jpg/wiki/File:Cartoon_CGRO.jpg,
http://commons.wikimedia.org/wiki/File:Chandra_X-ray_Observatory.jpg.
Public Domain.
(27) CK-12 Foundation.. CC-BY-SA.
(28) NASA.http://en.wikipedia.org/wiki/Image:Aldrin_Apollo_11.jpg. GNU-FD.
(29) http://www.jpl.nasa.gov/missions/mer/images.cfm?id=284. Public Domain.
(30) NASA.http://en.wikipedia.org/wiki/Image:Launch_Pad_39B.jpg. Public
Domain.
(31) NASA/ESA.http://commons.wikimedia.org/wiki/Image:
Betelgeusestar%28Hubble%29.jpg. Public Domain.