Term
CHAPTER 26
Life developed: |
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Definition
| 4 billion years ago. No traces of life on land until 400 million yrs ago. |
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Term
CHAPTER 26
Cambrian Explosion |
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Definition
| 1/2 billion years ago, the diversity and complexity of life on earth dramatically increased. All fossils from Cambrian period are sea creatures. Best known fossils: Trilobites |
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Term
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Definition
| Meteoroid colliding with Earth and producing a visible light trace in the sky |
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Term
CHAPTER 26
Miller Experiment (1952) |
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Definition
| stimulating conditions on Earth when life began 4 billion yrs ago. Experiment produced some of the fundamental building blocks of life: amino acids, fatty acids, and urea. Water (oceans), primitive atmospheric gases (hydrogen, ammonia, methane) and energy from electric discharges (lightening). |
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Term
CHAPTER 26
Primordial Soup |
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Definition
| Early oceans on Earth were probably filled with a rich mixture of organic compounds |
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Term
CHAPTER 26
Theory of Extraterrestrial Origin of Life |
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Definition
| most primitive living entities transported to Earth in meteorites or comets. Some meteorites show traces of amino acids. Untestable. |
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Term
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Definition
| single amino acids assembled into long protein-like molecules when they cool in water |
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Term
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Definition
| oldest fossils known. Built up layer by layer from single-celled creatures similar to bacteria ~3.5 billion yrs ago |
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Term
CHAPTER 26
Humans have existed for? |
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Definition
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Term
CHAPTER 26
Could life originate on another world if conditions were suitable? |
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Definition
| miller experiement indicates probably |
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Term
CHAPTER 26
Will life always evolve toward intelligence? |
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Definition
| if intelligence favors one species over another, then yes |
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Term
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Definition
| for chemical reactions and as transport mediaum. REQUIREMENT OF LIFE |
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Term
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Definition
| to avoid rapid vaporization of water; gasses need for organic compounds. REQUIREMENT FOR LIFE |
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Term
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Definition
| keep water liquid; avoid disintegration of organic compounds; activate complex chemical reactions. REQUIREMENT FOR LIFE |
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Term
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Definition
| for life to evolve from simple organic compounds into higher life forms: several billion yrs. REQUIREMENT FOR LIFE |
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Term
CHAPTER 26
Most promising candidate for life outside of Earth |
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Definition
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Term
CHAPTER 26
Requirements for life in other planetary systems |
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Definition
1. stable orbit around the star
2. time for evolution (only F5 or less massive stars
3. Moderate temperatures: life zone around the star |
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Term
CHAPTER 26
Arecibo Message |
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Definition
| Resulting 23x73 grid contained basic information about our human society |
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Term
CHAPTER 26
Search for Extraterrestrial Intelligence (SETI) |
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Definition
| programs to listen for intelligent messages from space. Highly controversial because of the uncertain prospects of positive results |
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Term
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Definition
| The number of technological civilizations per galaxy. |
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Term
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Definition
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Term
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Definition
| meteor that survives the plunge through the atmosphere to strike the ground |
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Term
CHAPTER 25
One meteorite is expected to strike a building somewhere on Earth every: |
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Definition
|
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Term
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Definition
| tracing the tracks of meteors in a shower backwards, they appear to come from a common origin |
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Term
| A constellation must consist of a number of stars all: |
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Definition
| within a boundary in the same general angular area of the sky |
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Term
| As viewed from Earth's northern hemisphere, describe the daily motion of Polaris |
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Definition
| It stays fixed in the northern sky near the celestial pole |
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Term
| refer to the figure above. What is the Moon's phase as viewed from Earth? |
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Definition
|
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Term
| Refer to the figure above. If we were on the Moon, what would be the phase of the Earth? |
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Definition
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Term
| If a star crosses my local meridian at 11 PM tonight, one week later the same star will closes the meridian at: |
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Definition
About 10:32 PM
Sidereal Time: 4 minutes less/day. So 7x4=28 minutes. 11:00 PM-28 minutes= 10:32 PM |
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Term
| An elephant and a mouse would both have the same weight-zero- in gravitaion free space. both are moving toward you with the same speed. Which of the following correctly descirbes the effect when they bump into you? |
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Definition
| The mouse has less inertia and is easier to stop |
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Term
| The zodiac constellations mark the celestial equator in the sky. |
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Definition
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Term
| If the moon rotated once about its axis for every orbit around the Earth, then: |
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Definition
| We would never be able to see one side of the moon |
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Term
| Suppose you measure the length of a shadow cast by a telephone pole at 12PM (noon), on the day of the summer solstice (June 20), here in Denton, Tx (lattitude 33 degrees). A week later you measure the shadow again at noon. which of the following best describes the shadow on this second observation? |
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Definition
| The shadow will be longer because the sun will be lower in the sky |
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Term
| The _____ produces tides on the Earth. |
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Definition
|
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Term
| What causes summer here in the northern hemisphere? In the summer, ________ |
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Definition
| The Earth's northern hemisphere is tilted toward the sun |
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Term
| Newton concluded that some force had to act on the Moon because: |
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Definition
| a force is needed to pull the moon away from straight-line motion. |
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Term
| Although general relativity is currently the most general theory of gravitation, most everyday experiences are adequately described by Newton's Law of Gravity. |
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Definition
|
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Term
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Definition
| Heavy and light objects fall at the same rate |
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Term
| If the Moon will be third quarter phase on June 26, what phase will it be one week later? |
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Definition
|
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Term
| Our solar system contains |
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Definition
| a single star and planets |
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Term
| What would a person weigh if the mass of the earth were to double but the radius of the earth were to remain the same. |
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Definition
|
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Term
| the Earth's eastwardly rotation about its axis causes |
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Definition
| the stars to rise in the East and set in the West |
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Term
| The distance between Earth and Sun |
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Definition
| is called an Astronomical Unit |
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Term
| _____ is the slow change in the Earth's axis of rotation. |
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Definition
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Term
| On a clear evening in the summer we see a different set of stars than we see on a similar evening in the winter. why? |
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Definition
| The Earth's yearly motion around the sun points the observer in a different direction |
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Term
| The accurate observations of ____ allowed ___ to determine the three laws of planetary motion? |
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Definition
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Term
| Satellites remain in orbit instead of falling to Earth because they are beyond the remain pull of Earth's gravity |
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Definition
|
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Term
| the primary reason that the Moon goes through a full cycle of phases in a month is: |
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Definition
| the orbital motion of the moon about the earth |
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Term
| Astronomers have developed a system of celestial coordinates to define the position of objects on the sky. The east-west position is termed____ and the north south position is termed |
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Definition
| Right ascension and declination |
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Term
| If the orbit of a planet has a semi-major axis of 4 AU. What is its sidereal period |
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Definition
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Term
| Navigators can find their latitude by measuring the angle from the northern horizon to the north celestial pole |
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Definition
|
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Term
| The law of gravitation is termed universal because it is a property of all material objects |
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Definition
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Term
| An observer on Earth's equator would find |
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Definition
| the celestial equator coincides with the horizon |
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Term
| The ___ is the point on the celestial sphere direclty above any observer |
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Definition
|
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Term
| suppose you are an astronaut during a space walk outside the shuttle. Which of the following is true? |
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Definition
| Your body exerts as much force on the moon as the moon does on you |
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Term
| In Sci Fi movies, it is common to use a space craft to travel across the Milky Way Galazy or to assert that we have been visited by alien space craft from the other side of the galaxy. If one has a space craft that can travel at the speed of light, how long will it take to get to go from one edge of the galaxy to the other. Assume the galaxy is 75,000 light years in diameter. |
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Definition
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Term
| Galileo's observations of the gibbous phase of venus proved: |
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Definition
| that Earth orbits the Sun |
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Term
| When two objects of unequal mass orbit each other, the center of mass is: |
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Definition
| always closer to the more massive of the two objects |
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Term
| At the EArth's North Pole, you could see: |
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Definition
|
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Term
| What does Kepler's second law indicate about the orbital speed of a planet |
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Definition
| a planet moves at its slowest when it is farthest from the sun |
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Term
| What does Kepler's second law indicate about the orbital speed of a planet |
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Definition
| a planet moves at its slowest when it is farthest from the sun |
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Term
| Conservation of angular momentum means that a spinning body tends to |
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Definition
|
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Term
| on Earth, lunar and solar eclipses do not occur each month. Why? |
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Definition
| the moon's orbit plane is tilted with respect to Earth's causing the moon's/earth's shadow to miss the earth/moon most months |
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Term
| Total solar eclipses always occur: |
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Definition
| during the time of the new moon |
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Term
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Definition
| the tendency for a moving body to stay moving, or a body at rest to stay at rest |
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Term
| The vernal equinox occured on March 20, 2008. On that day, a UNT astro student noted that the time from sunrise to sunset was: |
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Definition
|
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Term
| The cornerstone of the scientific method of inquiry is: |
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Definition
| observation, explanation, and prediction |
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Term
| From Earth, the moon and classical planets are always seen within a few degrees of the ecliptic. |
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Definition
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Term
| An anular eclipse occurs when: |
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Definition
| the moon is too far from the earth to completely blcok the solar disk |
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Term
| What would be the EArth's period of revolution around the sun, if the earth were further from the sun |
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Definition
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Term
| You live at a latitude of 33 Deg N. What is the angle between your northern horizon and north celestial pole? |
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Definition
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Term
| A ____ orbit is one where the orbiting object is always above the same location on EArth's surface |
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Definition
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Term
| If the distance between two masses is doubled, what happened to the gravitational force between the masses? |
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Definition
| It decreases by a factor of 4 |
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Term
| In the solar system, the main"net external force" that changes the motion of the planet is: |
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Definition
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Term
| At the time of the winter solstice the sun is: |
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Definition
| farthest south of the celestial equator |
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Term
| Which of the folowing is the largest? |
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Definition
| the distance from EArth to the sun |
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Term
| According to Keplers 3rd lawy, which of the following statements is true? |
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Definition
| for given semi-major axis, orbital period is the same for any eccentricity orbit |
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Term
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Definition
| A line around the sky directly above EArth's equator |
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Term
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Definition
| The apparent path of the sun against the background stars during the course of a year |
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Term
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Definition
| A north-south arc that passes thru the zenith point |
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Term
| There are _____ nanometers in one meter |
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Definition
|
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Term
| What is the wavelength of the longest wavelength light visible to the human eye? |
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Definition
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Term
| Your favorite radio state broadcasts at a frequencey of 1x10^8 Hz, what is the wavelength of this transmission? |
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Definition
|
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Term
| Light with a wavelength of 300 nm has a lower frequency than light with a wavelength of 500 nm. |
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Definition
|
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Term
| Light can behave as a particle or as a wayve |
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Definition
|
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Term
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Definition
| First to use a telescope to observe the univers, making several major discoveries |
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Term
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Definition
| Discovered that the planets orbit the sun in eliptical, not circular orbits |
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Term
| Proposed a heliocentric model of the universe |
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Definition
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