<P> This discipline is the science of celestial objects and phenomena that originate outside the Earth's atmosphere . It is concerned with the evolution, physics, chemistry, meteorology, and motion of celestial objects, as well as the formation and development of the universe . </P> <P> Astronomy includes the examination, study and modeling of stars, planets, comets, galaxies and the cosmos . Most of the information used by astronomers is gathered by remote observation, although some laboratory reproduction of celestial phenomena has been performed (such as the molecular chemistry of the interstellar medium). </P> <P> While the origins of the study of celestial features and phenomena can be traced back to antiquity, the scientific methodology of this field began to develop in the middle of the 17th century . A key factor was Galileo's introduction of the telescope to examine the night sky in more detail . </P> <P> The mathematical treatment of astronomy began with Newton's development of celestial mechanics and the laws of gravitation, although it was triggered by earlier work of astronomers such as Kepler . By the 19th century, astronomy had developed into a formal science, with the introduction of instruments such as the spectroscope and photography, along with much - improved telescopes and the creation of professional observatories . </P>

What object do scientists use to explain ideas about the natural world