earth and universe

• Science


  A collection of known truths about the Universe that develops and expands over time
• Cosmos


  Another word for universe
• Cosmology


  The study of the origin, evolution and fate of the universe
• Science is dynamic and ever changing
• Science develops when better models are found, clearer and more useful mechanisms are used to explain a group of phenomena, more accurate and precise details are observed
• Constant change


  Brought about by disintegration or corruption of things into more basic parts, and the need for constant intervention (e.g. force) that keep things from their original state or condition
• Modern scientists know these patterns are produced because the Earth spins on its own axis and revolves around the sun
• Greeks believed that objects were made up of four elements: air, earth, fire, and water
• They supposed that there were different types of motion that caused stationary objects to move and moving objects to stop
• Terrestrial domain


  Imperfect, tendency of things to attain perfection is the cause of their motion
• Celestial domain


  Perfect, can only be made up of the perfect substance they called "ether" and can only move in perfect motion: circular in path and constant in speed
• Fire and water naturally move away from the center
• They already know the effect of air drag being related to medium density (air or water) as well as the mass of the object
• Natural Motion


  The tendency of objects to go back to their natural state
• Voluntary Motion


  The ability of humans (as well as other animals) to move because they have the will or the capacity to do so
• Involuntary Motion


  The motion caused by unnatural conditions
• Diurnal motion/daily motion of the sky


  The apparent movement of stars and other celestial bodies around the Earth, caused by Earth's rotation from west to east
• Annual motion of the sky


  The apparent yearly movement of the Sun across a background of stars, caused by Earth's revolution around the Sun
• Earth's precession


  The conical motion of Earth's axis as it spins, completing one cycle every 26,000 years
• Around 500 BCE, Pythagoras and his pupils proposed that Earth was round
• Anaxagoras conducted observations that supported Pythagoras' proposal, observing that during a lunar eclipse, the Earth's shadow was reflected on the moon's surface
• Aristotle listed several arguments for a spherical Earth, including the shape of the moon and the Sun, the positions of the North Star, and the disappearance of the ships when they sailed over the horizon
• Eratosthenes attempted to measure the circumference of the Earth, using observations from Syene and Alexandria
• Models of the universe


  • Geocentric
  • Heliocentric
• Eudoxus' Model


  27 concentric spheres with Earth as the center, for the Sun, Moon, planets, and the stars
• Aristotle's Model


  56 spheres guiding the motion of the Sun, Moon and the five known planets, filled with the divine and eternal "ether"
• Aristarchus' Model


  The Sun is the center of the universe, with the Moon orbiting a spherical Earth which revolves around the Sun
• Ptolemy's Model


  Geocentric model with epicycles, deferents, and equants to explain the "imperfect" motions of the planets
• Copernicus' Model


  The Sun, not the Earth, is the center of the universe, with the Earth rotating on its axis, revolving around the Sun, and undergoing precession
• Eudoxus', Aristotle's, and Ptolemy's models have the Earth as the center of the universe while Aristarchus' and Copernicus' models have the Sun as the center
• Ptolemaic model introduced the concepts of epicycle, deferent, and equant to explain the observed "imperfect" motions of the planets
• Copernicus' model recognized that the Earth rotates on its axis, revolves around the Sun, and undergoes precession