Astronomy Essay Example | Topics and Well Written Essays - 500 words - 8

Astronomy - Essay Example Astronomical units are used for any measurement which has a certain reasonable length that humans can attain or reach. Light-years are usually reserved for objects too far away to ever be reached by one human’s lifetime. Stellar magnitude is the size and direction of a star. This is basically the star’s displacement. The difference between absolute and apparent magnitudes is that absolute magnitudes are fixed, real-time figures of information—whereas apparent magnitudes are just estimates based on what the human eye can see. That is the difference between the two phrases. Hipparchus originally drew his magnitude scale using very rudimentary calculations and tools. Today’s astronomers have modified it slightly by using more advanced techniques and a much more modern approach to the magnitude scale. Now, physics students all over use the magnitude scale developed by today’s most advanced and talented scientists. A. Compare the Ptolemaic and Copernican models of the universe. State the main tenet of each theory; how they are alike or different, what evidence each used to support the ideas, and how each explained the retrograde motion of the inner planets. (150 words)†¨ The Ptolemaic model of the universe stated that the universe revolved around the earth. Copernican theory stated that the model of the universe which was correct basically involved the universe revolving around the sun. They are both alike in the fact that both models involved the universe revolving around something—it was just that Ptolemy got it wrong. The evidence that Ptolemy used to support his claim was basically, he didn’t have evidence. It was by royal decree that the ruler in power wanted the earth to be the center of the universe. The evidence Copernicus used to show that the earth revolved around the sun was the entity of the eclipse—showing that the