Skylab was an orbiting laboratory launched by a
Saturn V rocket in May 1973.
pictured above, was visited three times by
who sometimes stayed as long as two and a half months.
Many scientific tests were performed on
including astronomical observations in
Some of these observations yielded valuable information about
our Sun and about the
mysterious X-ray background -
radiation that comes from all over the sky.
Skylab fell back to earth on 1979 July 11.