Related by context. Frequent words. (Click for all words.) 65 observatories 59 observatory 59 astronomical observatory 56 optical telescope 55 interplanetary spacecraft 55 telescopes 55 astronomical observations 53 Pan STARRS 53 infrared telescope 53 Kitt Peak 53 telescope 53 spacecraft orbiting 52 Voyager spacecraft 52 IceCube 52 astronomy 51 geodesy 51 optical telescopes 51 X ray telescope 51 robotic explorers 51 astronomers 51 Keck Observatory 50 unmanned spacecraft 50 remote sensing satellites 50 Mauna Kea Hawaii 50 spacecrafts 50 WM Keck Observatory 50 orbiting Saturn 50 XMM Newton 50 Southern Observatory ESO 49 Cassini Huygens 49 MARSIS 49 Palomar Observatory 49 planetary missions 49 CALIPSO 49 ESO Very Large Telescope 49 orbiting telescope 49 Remote sensing 49 Very Large Array 49 Lick Observatory 49 microlensing 49 Thirty Meter Telescope 49 lunar orbiter 48 WFC3 48 spacecraft 48 Astrophysicists 48 sundials 48 solar corona 48 satellites orbiting 48 NASAs 48 polar orbiting 47 Titan Saturn 47 Opportunity rover 47 lava tubes 47 particle detector 47 Hinode 47 geodetic 47 Observatories 47 physicists 47 Telescope 47 rock outcrop 47 rovers Spirit 47 colliders 47 outer planets 47 Polar Regions 47 Observatory 47 scientists 46 interferometer 46 ringed planet 46 Cosmic rays 46 satellites 46 DubaiSat 1 46 moon Charon 46 Mars Pathfinder 46 reconnaissance satellites 46 Very Large Telescope 46 Arecibo Observatory 46 Jodrell Bank 46 Nicolaus Copernicus 46 COROT 46 OSIRIS 46 adaptive optics 46 remote sensing satellite 45 hydrothermal vent 45 remote sensing 45 SMOS 45 gravitational wave 45 Orion Nebula 45 Galaxy Evolution 45 planetary exploration 45 powerful particle accelerator 45 NASA Cassini spacecraft 45 robotic spacecraft 45 orbiting observatory 45 seismographs 45 Lowell Observatory 45 VLBA 45 IKONOS 45 lunar 45 manned spacecraft 45 Saturn moon Enceladus 45 NASA ESA Hubble