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Download Explain. How is Copernicus`s description of the system of planets
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Warm up • People usually say that the sun rises in the east, moves across the sky, and sets in the west. Is this description literally correct? Explain. • How is Copernicus's description of the system of planets different from Ptolemy's description? The Solar System Brahe and Kepler • Brahe observed the positions of the planets for about 20 years • Kepler had discovered that the orbit of each planet is an ellipse Inertia and Gravity • Newton concluded that two factors—inertia and gravity—combine to keep the planets in orbit. • Inertia-the tendency of a moving object to continue in a straight line or a stationary object to remain in place. • Gravity- attracts all objects toward one another. The strength of gravity depends on the masses of the objects and the distance between them The Sun •The sun's energy comes from nuclear fusion •In the process of nuclear fusion, hydrogen atoms join together to form helium. occurs only under conditions of extremely high temperature and pressure The Sun's Atmosphere •The sun's atmosphere has three layers: the photosphere, the chromosphere, and the corona The Inner Planets •The four inner planets are small and have rocky surfaces The Outer Planets •The first four outer planets—Jupiter, Saturn, Uranus, and Neptune—are much larger than Earth, and do not have solid surfaces. Comets, Asteroids, and Meteors • Comets are chunks of ice and dust whose orbits are usually very long, narrow ellipses • asteroids, are too small and too numerous to be considered fullfledged planets. Most asteroids revolve around the sun between the orbits of Mars and Jupiter • meteoroid is a chunk of rock or dust in space. Meteoroids usually come from comets or asteroids Rockets and Satellites • A rocket moves forward when gases expelled from the rear of the rocket push it in the opposite direction • Satellites and space stations are used for communications, navigation, collecting weather data, and research. Phases, Eclipses, and Tides • The positions of the moon, Earth, and the sun cause the phases of the moon, eclipses, and tides. • The moon revolves around Earth and rotates on its own axis. • It takes the moon about 27.3 days to revolve around Earth. • When the moon's shadow hits Earth or Earth's shadow hits the moon, an eclipse occurs • solar eclipse occurs when the moon passes between Earth and the sun, blocking the sunlight from reaching Earth • A lunar eclipse occurs at a full moon when Earth is directly between the moon and the sun • As Earth rotates, the moon's gravity pulls water toward the point on Earth's surface closest to the moon. The Structure and Origin of the Moon • This diameter is only one fourth Earth's diameter. The moon's average density is about the same as the density of Earth's outer layers • The theory of the moon's origin that best fits the evidence is called the collision theory. • Material from the object and Earth's outer layers was thrown into orbit around Earth. • Eventually, this material combined to form the moon. Galaxies • Astronomers have classified most galaxies into three main categories: spiral galaxies, elliptical galaxies, and irregular galaxies. • Spiral Galaxies Photo A shows a galaxy that has the shape of twin spirals, called a spiral galaxy. These views show that spiral galaxies have arms that spiral outward, like pinwheels. • Not all galaxies have spiral arms. Elliptical galaxies look like flattened balls. So elliptical galaxies contain only old stars. • Irregular Galaxies Some galaxies do not have regular shapes. The Large Magellanic Cloud is an irregular galaxy about 160,000 light-years away from our galaxy.