^* The four observatories, were they to act in concert, seek to observe the universe through a considerable portion of the electromagnetic spectrum—Hubble, the best known, investigating all the way from ultraviolet to the near-infrared, by way of the entirety of the visible spectrum. The Compton Gamma Ray Observatory, sent into orbit aboard a shuttle in 1991, looked at violent and high-energy events out in space, those that emitted bursts of gamma rays. In 1999, the Chandra X-ray Observatory, also dropped from a shuttle, looks at X-ray emissions from black holes and quasars. Finally, in 2003, a Delta rocket took the Spitzer Space Telescope up into high solar orbit, from where it observes thermal infrared emissions, invisible from Earth because the very short wavelengths (as low as three microns) cannot penetrate Earth’s atmosphere. The Compton Gamma Ray Observatory reentered the atmosphere and is no more: the remaining three are still working like a charm.