How many space telescopes and observatories have been launched into space?

In this new Hubblecast episode, Dr. J guides us through the sixth chapter of Eyes on the Skies, the International Astronomical Union’s movie celebrating the telescope on its 400th anniversary in 2009. There’s no better place for a telescope than space itself. Above the Earth’s atmosphere observations are no longer hampered by air turbulence, so telescopic images of distant stars and galaxies are razor-sharp. Unlike a ground-based telescope, an instrument in Earth orbit can operate twenty-four hours a day a