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| is the study of all physical objects beyond Earth. |
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| the time required for the Earth to revolve once around the sun. |
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| is roughly the amount of time required for the moon to revolve once around the earth. |
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| is the time required for the Earth to rotate once on its axis |
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| 140 CE, was a Greek astronomer that developed the theory that the Earth was at the center of the universe and that the sun and other planets revolved around the earth. This was called the Ptolemaic theory which was incorrect but was used in Europe for more than 1500 years. |
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| 1543, was a Polish astronomer who published a new theory that the sun was the center of the universe and the planets revolved around the sun in circular paths; Copernicus's theory was correct but not widely accepted at the time. |
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| late 1500's, was a Danish astronomer that favored an Earth-centered universe; he believed that other planets revolved around the sun but that the sun and the moon both revolved around the Earth. While this was incorrect, he did record very exact data on the positions of the sun, moon and planets. |
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| was Brahe's assistant; Kepler in 1609, announced some new laws of planetary motion. He stated that all the planets revolve around the sun in an ellipse (elongated circle), and that the sun is not in the exact center of their orbital path. |
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| 1609, became the first person to use a telescope to observe objects in space; he discovered four moons orbiting Jupiter, craters and mountains on the moon, and sunspots. |
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in 1687, explained why planets revolve around the sun and why moons revolve around planets; Newton explained that gravity keeps all these objects in orbit. Newton formulated 3 laws of motion:
1. The Law of Inertia-Newton's 1st Law of Motion-an object at rest will remain at rest; and an object in motion will remain in motion unless acted upon by an unbalanced force.
2. Newton's 2nd Law of Motion-shows the relationship between force, mass and acceleration. Force=Mass*Acceleration.
3. Newton's 3rd Law of Motion-for every action there is an equal and opposite reaction. |
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| 1924, began researching galaxies beyond our galaxy, the Milky Way. He discovered a fuzzy patch in the sky-a new galaxy; this meant that the universe was much larger than just our galaxy. |
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| Robert Wilson & Arno Penzias |
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| 1964, two scientists that accidentally found radiation coming from all direction in space; they believed that this radiation called cosmic background radiation was left over from the big bang. |
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| An instrument that collects light and concentrates it for better observation. |
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| telescope with two lenses that allows the viewer to see millions of stars. |
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| telescope that uses a set of lenses to gather and focus light. A refracting telescope's size is limited by the size of the objective lens. |
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| use curved mirrors to gather and focus light; this type of telescope is the most widely used by astronomers. |
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| an optical telescope that produces images that are as good as or better than any images produced by optical telescopes in Earth. |
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| Electromagnetic Radiation |
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| all forms of energy that travel through space as waves. EM waves travel the speed of light (3.00*108 m/s) |
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| is all of the wavelengths of electromagnetic radiation, most of which is invisible to our eyes. Earth's atmosphere blocks most EM radiation. Some ultraviolet and wavelengths as well as all visible light and radio wavelengths can pass through the Earth's atmosphere.l |
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| galaxies that have a bulge at the center and spiral arms which are caused by the rotation of the galaxy. These arms are formed from the stars at the outer edges of the galaxy. Astronomers believe our galaxy (The Milky Way) is a spiral galaxy. |
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| galaxies that are shaped like elongated circles; these galaxies are composed of mostly old stars because they have very little dust and gases to form new stars. |
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| galaxies that have irregular shapes that don't fit into any other class. Many of these galaxies are close to spiral galaxies which may be distorting their shape. |
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| giant clouds of gas and dust; nebula's are found in spiral galaxies. |
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| are groups of older stars; looks like a ball of stars located in a spherical halo, or ring that surrounds spiral galaxies. |
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| groups of stars that are usually located along the spiral disk of a galaxy. New open clusters have bright, blue stars. |
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| are star-like sources of light that are extremely far away; they are among the most powerful energy sources in the universe. Some scientist believe that quasars may be the core of young galaxies that are in the process of forming. |
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| is equal to the distance that light travels through space in 1 year (9.5 trillion km in one year.) |
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| the study of the origin, structure, and future of the universe. |
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| states that the universe began with a tremendous explosion. |
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| a year in which a day is added to the calendar |
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