The Universe Essay Research Paper Student

The Universe Essay, Research Paper Student’s Name: Paul Blanton The Universe Summary : 100% 5 correct out of the 5 marked for grading 1. What is the composition of the Sun’s surface? Your Answer: 94% hydrogen, 5.9% helium, .1% other The Sun’s surface is called the photosphere and it is made up (by number of atoms) of about 94.0% hydrogen and 5.9% helium, with only traces of the heavier elements making up the other 0.1% 2. State the two primary motions that the Sun is undergoing. Your Answer: It rotates on its axis, and it revolves around the center of the Milky Way Galaxy. The Sun’s equatorial region rotates about its own axis every 25 Earth days, while the polar regions take slightly longer. The Sun also revolves about the center of the Milky Way Galaxy with a period

of one revolution every 250 million years. 3. What are sunspots. Your Answer:asdf Sunspots are patches on the surface of the Sun that are cooler than the surrounding region by several hundred degrees. They, therefore, appear as dark spots on the Sun’s hot surface, hence their name. They usually last for several days and sometimes up to several weeks. Sunspots are thousands of miles in width and are related to changes in the Sun’s magnetic field. Sunspots occur in greater numbers on the Sun’s surface in a regular 11-year cycle. 4. What is the celestial sphere? Your Answer: Imaginary transparent that surrounds the Earth which planets can be positioned. The celestial sphere is a huge, imaginary, transparent sphere that completely surrounds Earth and on which the observable

celestial objects that appear as part of the night sky can be positioned. This sphere undergoes an apparent rotation, as seen by an observer located on Earth’s surface, such that it accounts for the motions of all of the “fixed stars.” The Sun, Moon, and planets move across the surface of the celestial sphere with respect to the fixed stars along a general path called the ecliptic. An observer on Earth’s surface can only see half the celestial sphere at one time. It appears as a large, transparent, overhead dome moving westward, but this apparent motion is really caused by the motion of Earth as it rotates eastward. 5. What is the zodiac? Your Answer: a section which follows the path of the sun on the celestial sphere. The zodiac is a section extending around the

celestial sphere 8. above and 8. below the apparent path of the Sun across the sphere. This path is called the ecliptic. The zodiac is divided into 12 nearly equal sections, each of which is about 30. wide and 16. high. Each section has its apex at the Sun and extends outward to infinity. The names of these sections, often called the signs of the zodiac, are taken from the predominant constellation that can be seen in that region of the sky. 6. Define the unit of length called the parsec. Your Answer: Distance to a star when the star s parallel is one second of arc. One parsec is the distance to a star when that star exhibits a parallax angle of one second of arc. One parsec is equal to 3.26 light-years or 206,265 astronomical units. (See Figure 18.8 in the textbook for details

on parallax measurement and the distance unit, the parsec.) 7. What is meant by the absolute magnitude of a star? Your Answer: The apparent magnitude of a star if it were moved to ten parsecs from Earth. The absolute magnitude is defined as the apparent magnitude that a star would have if it were moved (in our imagination) to a location exactly 10 parsecs from Earth. Thus the absolute magnitude can be used to compare the true brightnesses of the stars. When we observe stars in their actual locations from Earth, their distances from us are primary factors in determining how bright they appear to be. The actual brightness that we observe when viewing a star from Earth is called the apparent magnitude of that star. 8. What is a Hertzsprung-Russell diagram? Your Answer: A plot of