Related by context. Frequent words. (Click for all words.) 47 sundials 46 telescope 46 planetarium 44 telescopes 42 astronomy 41 observatory 41 astronomical observatory 41 Astronomy 40 Telescopes 40 astronomical observations 40 optical telescope 40 Planetarium 39 CubeSat 39 sundial 38 seismometer 37 constellations 37 microscopes 37 infrared telescope 37 scanning electron microscope 37 Arecibo Observatory 36 Celestron 36 panoramic camera 36 Telescope 36 eyepiece 35 Observatories 35 spectrometer 35 optical microscope 35 adaptive optics 35 spectrometers 35 stargazer 35 celestial objects 35 Astrophysicist 35 camera obscura 35 Exploratorium 34 Lick Observatory 34 observatories 34 NRAO 34 celestial bodies 34 Planetary Laboratory 34 Rocketry 34 CCD camera 34 Sci Port 34 spectrograph 34 Lowell Observatory 34 Gemini Observatory 33 HiRISE 33 Starry Night 33 transmission electron microscope 33 thermal emission spectrometer 33 lunar 33 optical illusions 33 Hinode 33 binocular 32 Earth Observing 32 Palomar Observatory 32 LSST 32 LIGO 32 interferometer 32 astronomer 32 Astronomer 32 HRSC 32 Alpha Centauri 32 celestial 32 telescopic 32 occultation 32 IceCube 32 ESO Very Large Telescope 32 Kitt Peak 32 Thirty Meter Telescope 32 Johannes Kepler 31 Aurora Borealis 31 pinhole camera 31 infrared camera 31 carillon 31 Stargazing 31 celestial object 31 Pleiades 31 SMART Boards 31 remote sensing 31 Spectrometer 31 hay maze 31 Chabot Space 31 robotic arm 31 gravitational wave 31 cupola 31 Adler Planetarium 31 optical telescopes 31 overhead projector 31 remote sensing satellites 30 Orion Nebula 30 planetariums 30 Mars rover 30 amateur astronomers 30 astrophysics 30 PARI 30 WM Keck Observatory 30 Very Large Telescope 30 binoculars 30 seismographs 30 rover 30 NASA Lunar Reconnaissance