AST101H5 Lecture Notes - Lecture 4: Full Moon, Lunar Eclipse, Equinox
Document Summary
Many astronomical events repeat in regular cycles. The repetition of cycles help us understand them. Some cycles have been useful - timing of seasons, migration of animals - these were astronomy"s practical contributions. The stars in space are in different directions and at different distances - space is 3 - dimensional. However, stars are so far from the earth that they all appear to be the same distance. Therefore, we imagine the stars attached to the surface of a gigantic sphere surrounding. Wherever we are on earth, earth blocks half the sky from our view. To organize the sky, we imagine images that sort of match the pattern of stars = constellations. Because stars are so far away, the constellations don"t change for many thousands of years, even though the stars are moving at high speeds. From a different solar system the constellations would look different.
