Change in Positions of the Sun, the Moon and the Stars
The sun appears to move across the sky from day to day due to the rotation of the earth around its own axis. This forms the basis of a night and a day as the sun sets in the east and sets in the west due to the rotation of the earth. The monthly shift in the sun’s position in the sky is due to the year-long revolution of the earth around the sun with its axis staying fixed in space, making it tilt various regions of our planet to the sun more than others in its revolution.
The moon appears to change its position in relation to the earth due its 27-day-long revolution around the earth. This causes the above pointed motion of our planet’s satellite in the sky as the earth is also rotating around its axis and revolving around the sun. These changes occur as the moon’s appearance varies in accordance to its relation to the earth as well as the sun changing the shape of its visible surface.
Stars seem to change their positions in the earth due to the changing position of the earth to them as it revolves around the sun and rotates about its axis. In fact, the stars are stationary within space making the earth the dynamic factor that leads to different views of the stars from different angles.
Ancient Geocentric Models of the Universe
By 350 BC, the geocentric model of the universe prevailed. This came after the confirmation that the earth is spherical. Aristotle and Ptolemy had their models of the universe based on the facts and theories that existed at the time. The earth was the center of the universe according to these models. Aristotle explicated his model based on the four elements of life: earth, water, air and fire. Air and fire rose when in the atmosphere and heavenly bodies did not fall onto the earth thus he hypothesized that different elements formed them. Ptolemy introduced equations into his geocentric model explaining that the center of orbits of the planets did not land on the earth.
Several discoveries and means of explaining the structure of the universe arose during renaissance. The heliocentric model of the universe brought back Plato’s ideas of symmetry and order in the structure of the universe. New stars, sunspots and several heavenly objects discoveries led to the understanding of the universe. Instruments like the telescope that were invented during the renaissance aided in the exploration of the universe. Great scientists like Copernicus, Kepler, Brahe, Galileo and Newton turned tables in astronomy settling on correct astronomical deductions.
Galileo and Kepler
Johannes Kepler’s work contributed in astronomy in turning the view of the orbits of the planets as circular to elliptical. He improved on the Copernicus model that explained circular orbits that led to discrepancies in calculations. The elliptical orbits that Kepler suggested fitted into the data perfectly.
Galileo improved the Copernican view of the universe after developing a telescope that enabled him to scrutinize space efficiently. He observed the features of other planets and explained them to detail up to Saturn. The scientist observed the moons on other planets and explained the stars within the Milky Way. Galileo published works on the heliocentric model of the universe against the church’s warning.
The electromagnetic waves are electric and magnetic disturbances that have the capability of transferring energy from one point to another. They carry energy through space in the form of quanta (small energy packets). The analyzed waves are not affected by electric and magnetic fields making them resistant to alteration. Furthermore, they either have de-ionizing, rotational or vibratory properties that act as a measure with which information of their source can be obtained. Heavenly bodies emit them, and interception of those waves gives information about such heavenly objects.