Homework #1 - Exploring the Heavens/Introduction &...

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Fill in the Blank Part 1 1. Earth and the Sun are part of a vast collection of matter called the Milky Way Galaxy . 2. The apparent path of the Sun across the sky is known as the ecliptic . 3. On December 21, known as the winter solstice , the Sun is at its lowest point on the celestial sphere. 4. The solar day is measured relative to the Sun; the sidereal day is measured relative to the star . 5. To explain the daily and yearly motions of the heavens, ancient astronomers imagined that the Sun, Moon, stars, and planets were attached to a rotating celestial sphere . 7. Declination measures the position of an object north or south of the celestial equator . 8. A lunar eclipse can be seen by about half of Earth at once. Discussion Questions Part 1 3. How and why does a day measured by the Sun differ from a day measured by the stars? A sidereal year, which is measured by the stars, is about 20 minutes longer than a tropical year, which is measured by the sun. This is because of precession. Because of the tilt of Earth’s axis, it slowly changes its direction over the course of time. 4. Why do we see different stars in summer than in winter? Because of the Earth’s rotation. 5. Why are there seasons on Earth? Seasons result from the tilt of Earth’s axis with respect to the plane of its orbit. 6. If one complete hemisphere of the Moon is always lit by the Sun, why do we see
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Homework #1 - Exploring the Heavens/Introduction &...

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