Changes

In the Middle East and Asia, astronomy had developed and retained knowledge from ancient periods to allow the development of accurate calendars and to make accurate predictions of the movement of celestial bodies. Astrolabes and other navigation equipment became commonly used to assist in observing the positioning of stars to inform sailors of their relative position, where such technologies derived from earlier, ancient observations (Figure 2). However, in Western Europe, after the fall of Rome, astronomy had made limited or few advancements. <ref>For more on navigation and star positioning, see: Denny, M. (2012). <i>The science of navigation: from dead reckoning to GPS.</i> Baltimore: John Hopkins University Press.</ref>

This changed by the 16th-17th centuries. Advancements in optics, made in the Islamic world by the early Medieval period, and then created into a telescope used by Galileo Galilei that could observe celestial bodies. Observations by Galileo led to him seeing moons in relation to other planets, craters on the moon, and many other observations. This, once again, led astronomy to become an important science that also led to other developments, in particular physics in the 18th century began to then be closely associated with astronomy. Phases of planets in their rotation were noticed by Galileo, leading him to support Copernicus in his observation on planetary rotation. Isaac Newton used calculus to explain gravity in relation to the planetary bodies. This helped Newton to more fully develop his theory of gravity. Mathematical laws now became the way in which planetary and celestial motion was understood, leading to the fuller development of the field of physics as well.<ref>For more on the development of telescope development and planetary motion, see : Cole, G. H. A., & Woolfson, M. M. (2013). <i>Planetary science: the science of planets around stars.</i> (2nd ed). Boca Raton: CRC Press.</ref>