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| The Geocentric Theory | A theory with the earth at the center with everything else moving around it. Ptolemy, an ancient Greek philosopher, tried to perfect it but it was difficult to understand. |
| Problems with the Geocentric Theory | 1. Some planets appeared close at times and far away other times. The eccentric orbit ( oval shape ) of these was a good explanation. 2.Some planets seemed to slow down at times. Ptolemy tried to explain this with the idea of epicycles. 3.ÿÿÿÿ This model was both inaccurate and complex. |
| The Heliocentric Theory | With "helio" referring to the Sun (helium based) and "centric" referring to the center, this theory states that the Sun is at the center of the universe with all objects orbiting it in a circular motion. This model developed by Nicolaus Copernicus in the early 1500s was a more accurate model. One argument against the theory was that the earth would have to rotate to have days and nights if the Sun stood still. So birds in flight would be left behind if the earth rotated. Copernicus explained that the atmosphere drags along with the earth as it rotates, including the birds. Copernicus was able to answer all the arguments against his theory. |
| Foucault's Pendulum | The Foucault pendulum showed that as a pendulum moved over time it changed position. This was do to the earth's motion. |
| Tycho Brahe | was an accurate astronomical observer. His observations were so accurate that even though he supported Ptolemy, his work proved the heliocentric theory. |
| Johannes Kepler | was a strong Christian and a brilliant mathematician. When forced to move to Prague, he began work with Tycho. Kepler was able to explain many of Tycho's observations with math. This gave further evidence of the truth of the heliocentric theory. |
| Galileo Galilei | developed the first telescope for the purpose of looking to the stars. His first telescope was a retracting telescope that uses mirrors to enlarge the image. He observed that Venus had phases like the moon. He discovered that many objects orbited other object and not just the Sun. |
| Kepler's three laws of planetary motion. | 1.Planets move in an elliptical manner not circular. This means it has an oval shape. It has two foci; one is the Sun with the other point out in space. 2.The second law states that the speed of movement for the planet's year is determined by its distance from the Sun. The closer, the faster; the farther away the slower. 3.ÿÿÿÿ The average distance the planet is from the Sun will determine how long it takes to get around the Sun. They are proportional. P2=D3 |
| Sir Isaac Newton | developed laws on motion and gravity. |
| Law of Gravity | states that there is a force of attraction between all bodies in the universe. The greater the mass the greater the attraction, but as distance decreases so does the strength of attraction. The Moon is actually falling toward the Earth, but the movement of the Moon keeps it from hitting the Earth. |
| Our solar system | is defined as the Sun and all object that revolve/orbit around it. How far it reaches is debated. Planets are defined as objects that orbit the Sun. They must have a spherical shape. It does not share its orbital space with any other significant object other than the moons. |
| Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune | Name the Planets |
| Terrestrial planets | are those approximately the size of the Earth with rocky surfaces. These are Mercury, Venus, and Mars. |
| Jovian planets | are those with that have a gaseous atmosphere so thick that probes are not able to reach their surface. These are extremely large planets like Saturn, Jupiter, Uranus, and Neptune. |
| Inferior Planets | planets closer to the Sun than Earth |
| Superior Planets | planets closer to Earth than the Sun |
| Mercury is the closest to the Sun. It has th most elliptical orbit. And at 88 days it is the fastest planets. Due to its slow rotation it only has 1.5 days during a year. | planet that is the closest to the Sun. It has th most elliptical orbit. And at 88 days it is the fastest planets. Due to its slow rotation it only has 1.5 days during a year. |
| Venus | planet that is the second from the Sun. Its day is longer than its year. |
| Venus | the brightest and hottest planet |
| Mars | Its is known as the red planet. It is the second most studied planet. |
| Jupiter | It is the largest planet. The Great Red Spot is a storm that orbits it. It has rings. |
| Saturn | is the planet with the most rings. It rotates the fastest. |
| Uranus | The only planet known to be tilted on its side. Its has rings. |
| Neptune | Is the farthest planet from the Sun. It is sometimes farther than Pluto. The Great Dark Spot is also a storm. |
| Objects that orbit the sun. Almost spherical in shape and are rigid. They can share their orbit with another object. They are not moons; satellites of an object. They are not moons; satellites of an object. | Characteristics of Dwarf Planets |
| Pluto | was classified as a minor planet in 2006 because it is not large enough to clear its orbital space of other objects |
| Pluto | small planet with 5 moons |
| Pluto | Is it a planet or something else? |
| They are smaller (house size to about an 3rd of the moon). They have no atmosphere due to weak gravity. They have odd shapes; a lumpy appearance. They have an irregular composition. Many are not solid rock but clusters of rocks. | Characteristics of asteroids |
| Asteroids | Most are found in a belt between Mars and Jupiter |
| Comets | are an orbiting body with an extremely eccentric or elliptical orbit. They are composed of rock and ices; some believe they also may be made of frozen gases surrounded by gravel and dust. The tail is created by solar wind pushing radiation and gases away. The parts of a comet include two tails that are formed as ice melts; then dust and gas are pushed away by forces from the Sun. |
| Comets | composed of rock and ices and maybe frozen gases surrounded by gravel and dust |
| solar wind pushing gases and radiation away | Creates the tail of a comet |
