The Earth and the Stars

angle apparent astronomers atmosphere atoms average body bright called caused celestial cent close clouds comet compared constellation curve dark density depends diameter direction discovered disk distance earth east eclipse effect electric elements equal equator fall follow force galaxy give heat Hence hydrogen indicate intensity Jupiter known length less lies light lines magnetic magnitude March mass means measure method miles million minutes mirror months moon moon's motion Mount moving nearly nebula object Observatory observed occurs orbit parallax pass period photographic planet PLATE pole position present probably radiation rays reach reflected relative rise rotation scale seen solar sometimes space spectra spectroscope spectrum stars sun's sunspot surface telescope temperature thousand tion variable variation Venus wave Wilson