An amazing discovery of the last twenty years is that many galaxies have massive black hole in their centers. Dust and gas that fall into black holes radiate in the X-ray part of the spectrum. So if we look at the sky in visible light, we see stars. If we look at the sky in X-rays, we see black holes. NuSTAR will use advanced optics and detectors to observe the high-energy X-ray sky with much greater sensitivity and clarity than ever before. This June, NuSTAR will lift off on an Orbital Sciences Pegasus XL rocket. The rocket will be released from the bottom of a specially modified Lockheed L-1011 aircraft taking off from the Reagan Test Site on the Kwajalein Atoll in the Marshall Islands.