Earth Science Facts to Know



220 Environmental Science Facts to Know[pic]

Collated by K. Oshinsky for use at Wakefield High School

Introduction to Earth Science / Mapping

1. The Age of the Earth is 4.6x109 years old, 4.6 billion years old, 4,600 million years.

2. Earth science is the name for the group of sciences that deals with Earth and its neighbors in space.

3. Earth consists of four major spheres: the hydrosphere, the lithosphere/geosphere, atmosphere and the biosphere.

4. Earth can be divided into layers based on physical properties—the lithosphere, asthenosphere, outer core, and inner core.

5. The true shape of the Earth is an oblate spheroid. It is flattened at the poles and bulging at the equator. The best evidence for the spherical shape of the Earth are pictures from space.

6. No matter what kind of map is made, some distortion will always be present. Mercator maps are the most common “flat map” and have the greatest distortion near the poles.

7. Latitude lines (parallels) are drawn from east to west and measured from north to south (Equator). Longitude lines (meridians) are drawn from North Pole to South Pole and are measure from east to west (Prime Meridian). Latitude is based on the altitude of Polaris, (the North Star). Longitude is based on the observations of the sun (also a star).

8. The geographic poles (“True North” and “True South”) are fixed points located where the Earth’s axis passes and all lines of longitude converge (90oN and 90oS latitude).

9. The magnetic poles are the focus of the Earth’s magnetic fields and shift position due to changes in circulation within the Earth’s core. The geomagnetic poles are the points in the magnetosphere where Earth’s magnetic field passes into space (Auroras).

10. Topographic maps represent the Earth’s three-dimensional surface on flat maps. Contour lines connect points on a topo map with the same elevation. The closer the contour lines the steeper the slope. Contour lines bend upstream as they cross a stream or river.  

Chemistry and Minerals

11. An element contains only one type of atom. Therefore, an element cannot be broken down, chemically or physically, into a simpler substance.

12. An atom is a submicroscopic particle made of even smaller components called protons, neutrons, and electrons. An element contains only one type of atom.

13. Protons and neutrons each have a mass of one AMU (atomic mass unit). The atomic mass of an element is the mass of all protons plus the average mass of all neutrons found in an atom. Electrons do not contribute to the atomic mass.

14. Atoms with the same number of protons but different numbers of neutrons are isotopes of an element. Atoms with the same number of protons but different numbers of electrons are ions of an element.

15. Minerals have different properties due to their internal arrangement of their atoms.

16. Silicon and oxygen form earth’s basic mineralogical structural unit – the tetrahedron.

17. Streak is the color of a mineral in its powdered form.

18. Luster describes how light is reflected from the surface of a mineral.

19. Crystal form is the visual expression of a mineral’s internal arrangement of atoms.

20. The Mohs scale is a scale that can be used to determine a mineral’s hardness.

21. Cleavage is the tendency of a mineral to cleave, or break along flat, even surfaces; fracture is uneven breakage.

22. Density is a property of all matter that is the ratio of an object’s mass to its volume.

Rocks

23. [pic] The Rock Cycle

24. The three major types of rocks are igneous, sedimentary, and metamorphic.

25. Interactions among Earth’s water, air, and land can cause rocks to change from one type to another. The continuous processes that cause rocks to change make up the rock cycle.

26. Rocks that form when magma hardens beneath Earth’s surface are called intrusive igneous rocks. Magma at the Earth’s surface is called lava. When lava hardens, the rocks that form are called extrusive igneous rocks.

27. Igneous rocks are classified by texture (grain size). Coarse (large) grains = Intrusive - (cooled slowly below surface). Fine (small) grains = Extrusive (cooled quickly). Glassy (no visible crystals) = Extrusive.

28. Sediments are compacted and cemented to form sedimentary rocks. Sedimentary rocks (strata) form (flat) horizontal layers.

29. Under extreme pressure and temperature conditions, rock will change into metamorphic rock. These conditions are found a few kilometers below Earth’s surface and extend into the upper mantle. Metamorphic rock shows banding/foliation (stripes) and distorted structure.

30. The formation of igneous rock causes contact metamorphism.

Resources

31. A renewable resource can be replenished over fairly short time spans, whereas a nonrenewable resource takes millions of years to form and accumulate.

32. Fossil fuels include coal, oil, and natural gas.

33. Solar energy has two advantages: the “fuel” is free, and it’s non-polluting.

34. Nuclear fusion: combining atomic nuclei to produce energy (H ( He in stars). Clean but cannot be done with human technology. Nuclear fission: splitting atomic nuclei to release energy (nuclear reactors). Humans have the technology but don’t know what to do with the radioactive waste.

35. Some experts estimate that in the next 50 to 60 years, wind power could provide between 5 to 10 percent of the country’s demand for electricity.

36. Hydroelectric power: the water held in a reservoir behind a dam is a form of stored energy that can be released through the dam to produce electric power. Tidal power is harnessed by constructing a dam across the mouth of a bay or an estuary in coastal areas with a large tidal range. The strong in-and out flow that results drives turbines and electric generators.

37. Geothermal energy: hot water or steam, from fissures or volcanoes, is used directly for heating and to turn turbines to generate electric power.

38. Starting in the 1970s, the federal government passed several laws (including The Clean Air Act) to prevent or decrease pollution and protect resources.

Weathering, Erosion and Soil

39. Water, in any form, is responsible for most chemical weathering.

40. In nature, three physical processes are especially important causes of mechanical weathering: frost wedging, unloading, and biological activity.

41. When a rock is broken into smaller pieces, surface area increases and weathering rate increases.

42. Erosion involves weathering and the removal of rock. When an agent of erosion—water, wind, ice, or gravity—loses energy, it drops the sediments. This process is called deposition.

43. Human activities that remove natural vegetation, such as farming, logging, and construction, have greatly accelerated erosion.

44. Soil has four major components: mineral matter, or broken down rock; organic matter, or humus, which is the decayed remains of organisms; water; and air.

45. The most important factors in soil formation are parent material, time, climate, organisms, and slope.

46. Soil varies in composition, texture, structure, and color at different depths. The noticeable layers, or horizontal bands, in soil are soil horizons. The entire arrangement of horizons is called a soil profile. Each horizon has distinct features that reflect the characteristics of the parent rock and the conditions in which the soil formed.

47. Three common types of soil are pedalfer, pedocal, and laterite.

Groundwater

48. Porosity (percentage of empty space) does NOT depend on particle size.

49. Permeability, the ability to flow through ground material, pores must be connected. As particle size increases, permeability also increases.

50. Capillarity, the upward movement of water through the ground, depends on surface area. As Particle size decreases, capillarity increases.

51. Gravity is the main FORCE behind all erosion. Running water (streams, rivers) is the primary AGENT of erosion.  

52. Water constantly moves among the oceans, the atmosphere, the solid Earth, and the biosphere. This unending circulation of Earth’s water supply is the water cycle. Balance in the water cycle means the average annual precipitation over Earth equals the amount of water that evaporates.

53. The zone of aeration is the area where most of the pore spaces in the sediment and rock. The zone of saturation is the area where water fills all of the open spaces in sediment and rock. Groundwater is the water within this zone.

54. A drainage basin is the land area that contributes water to a stream. Much of the water in soil seeps downward until it reaches the zone of saturation.

55. A spring forms whenever the water table intersects the ground surface. A well is created when we dig down to the water table.

56. Stream velocity depends on slope and discharge (the amount of water moving through the stream at any one time).

57. Streams and rivers go through predictable life cycles based upon their supply of water.

58. Streams and rivers carve a V-shaped valley. Glaciers carve a U-shaped valley.

59. Karst areas typically have irregular terrain, with many caves and sinkholes due to their limestone bedrock and heavy rates of chemical weathering.

60. Measures to control flooding include the construction of artificial levees, building flood control dams, and placing limits on floodplain development. Overuse and contamination threatens groundwater supplies in some areas.

Plate Tectonics, Volcanism and Mountains

61. Wegner’s continental drift hypothesis stated that the continents had once been joined to form a single supercontinent (Pangaea).

62. Seismic data and drilling technology indicate that the geosphere is divided into three main parts: core, mantle and crust.

63. Earth’s core is thought to be mostly dense iron and nickel. Ocean crust is thin and composed of dense basalt. Continental crust is thick and composed of granite.

64. Isostasy describes Earth’s crust in equilibrium. Subsidence is the sinking of the crust and uplift is the lifting of the crust.

65. The three types of plate boundaries are convergent, divergent, and transform fault boundaries.

66. At the Mid-Ocean ridges (spreading center) new crust is created, age of the rock increases as distance from the ridge increases (divergent plate boundary) Ocean trenches (subduction zone) where old crust is destroyed.  (convergent plate boundary).

67. At a transform fault boundary, plates grind past each other without destroying the lithosphere.

68. According to the plate tectonics theory, the uppermost mantle, along with the overlying crust, behaves as a strong, rigid layer. This layer is known as the lithosphere.

69. Hot spot evidence supports that the plates move over Earth’s surface. The unequal distribution of heat within Earth causes the thermal convection in the upper-mantle (asthenosphere) that ultimately drives plate motion.

70. The primary factors that determine whether a volcano erupts violently or quietly include magma composition, magma temperature, and the amount of dissolved gases in the magma.

71. The three main volcanic types are shield volcanoes, cinder cones, and composite cones.

72. A caldera is a large depression in a volcano.

73. Intrusive igneous bodies, or plutons, are generally classified according to their shape, size and relationship to the surrounding rock layers.

74. The basic connection between plate tectonics and volcanism is that plate motions provide the mechanisms by which mantle rocks melt to generate magma.

75. The three types of stresses that deform rocks are tensional stress, compressional stress, and shear stress.

76. The three main types of folds are anticlines, synclines, and monoclines.

77. The major types of faults are normal faults, reverse faults, thrust faults, and strike-slip faults.

78. Mountains are classified by the dominant processes that have formed them. Mountains form due to uplifting, folding, faulting and volcanism.

79. Marine fossils (seashells…) on mountain tops indicate that the land has been uplifted.

Earthquakes

80. Earthquakes are vibrations of Earth, produced by the rupture and sudden movement of rocks, which are caused by stresses beyond the elastic limits of the rocks.

81. The point inside the Earth where the rupture generates earthquake energy is called focus. The point at the Earth's surface directly above the focus is the epicenter. A minimum of three (3)  seismograph station are needed to determine the location of an epicenter.

82. Elastic rebound theory: As rock is deformed, it bends, storing elastic energy. Once strained beyond its breaking point, the rock cracks, releasing the stored energy, which generates earthquake waves.

83. The Richter scale measures the energy released in an earthquake by measuring the size of the seismic waves. The Mercali scale measures the results of an earthquake, such as the shaking and damage that people actually feel and see.

84. [pic]Primary (P)waves : Pressure waves caused when rock is pushed or pulled forward or backward. Primary waves, the fastest wave sent out by an earthquake, travel down into the earth rather than along the surface.(Remember: P waves - primary, pressure, push-and-pull.

85. [pic]Secondary (S) waves: Shear waves caused when rock is shaken or whipped from side-to-side, like the wavy motion of a slithery snake. Secondary waves, the second-fastest wave sent out by an earthquake; travel down into the earth rather than along the surface. (Remember: S waves - second, shear, side-to-side).

86. [pic]Surface (L) waves: Up-and-down (rolling) or side-to-side motion of the earth surface. Surface waves, the slowest earthquake waves, travel along the surface of the earth rather than down into the earth. Although they are the slowest of all earthquake waves, L waves usually cause more damage to society than P or S waves. (Remember: L waves are always the last to arrive.

87. Mohorovicic Discontinuity “Moho": the boundary between the crust and the mantle. Differences in density between the two layers results in a change in velocity for seismic waves.

Earth’s History

88. Relative dating can’t tell us how long ago something took place. It can only tell us the sequence in which events occurred.

89. Radiometric/”Absolute” dating: calculating the approximate age of radioactive rocks based on the constant rate of decay of their radioactive isotopes (C-14 compared to C-12).

90. Uniformitarianism means that the forces and processes that we observe today have been at work for a very long time.

91. The law of superposition states that in an undeformed sequence of sedimentary rocks, each bed is older than the one above it and younger than the one below it. The principle of original horizontality means that layers of sediment are generally deposited in a horizontal position.

92. An unconformity represents a long period during which deposition stopped, erosion removed previously formed rocks, and then deposition resumed.

93. Intrusions and faults are younger than the rock they cut through.

94. Fossils are the remains or traces of prehistoric life, and they are important components of sediment and sedimentary rocks. The type of fossil that is formed is determined by the conditions under which an organism died and how it was buried.

95. The principle of fossil succession combines the law of superposition and the study of the fossils the rock layers contain. Index fossils are good markers for relative dating (widely spread, lived a short time).

Geologic Time

96. Geologists have divided Earth’s 4.6 billion year history into specific time units. Eons represent the greatest expanses of time. Eons are divided into eras. Each era is subdivided into periods. Finally periods are divided into still smaller units called epochs.

97. The Precambrian encompasses immense geological time, from Earth’s distant beginning 4.56 billion years ago until the start of the Cambrian period, over 4 billion years later.

98. Earth’s original atmosphere was made up of gases similar to those released in volcanic emissions today—water vapor, carbon dioxide, nitrogen, and several trace gases. Primitive organisms evolved that used photosynthesis and released oxygen.

99. Following the long Precambrian, the most recent 540 million years of Earth history are divided into three eras: Paleozoic, Mesozoic, and Cenozoic.

100. Life in early Paleozoic time was restricted to the seas.

101. A major event of the Mesozoic era was the breakup of Pangaea.

102. Many environmental factors contributed to the extinction of the non-avian (not bird) dinosaurs. The mammals adapted more successfully to these changes and the rise of mammals is a key event that characterizes the Cenozoic. Birds are the descendents of the raptor-like dinosaurs, such as T-Rex.

Ocean Floor

103. Just over 70 percent of Earth’s surface is covered by the global ocean.

104. The world ocean can be divided into four main ocean basins—the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, and the Arctic Ocean.

105. The topography of the ocean floor is as diverse as that of continents.

106. Today, technology—particularly sonar, satellites, and submersibles—allows scientists to study the ocean floor in a more efficient and precise manner.

107. The ocean floor regions are the continental margins (shelf, slope, rise), the ocean basin floor (trenches, plains, seamounts, guyots), and the mid-ocean ridge (spreading, vents).

108. In the Atlantic Ocean thick layers of undisturbed sediment cover the continental margin. This region has very little volcanic or earthquake activity (Mid-Atlantic Ridge).

109. In the Pacific Ocean oceanic crust is plunging beneath continental crust. This force results in a narrow continental margin that experiences both volcanic activity and earthquakes (Ring of Fire)

110. Ocean-floor sediments can be classified according to their origin into three broad categories: terrigenous sediments, biogenous sediments, and hydrogenous sediments.

111. Major resources from the seafloor include sand and gravel, evaporative salts, and manganese nodules.

Ocean Water and Life

112. Seawater density is influenced by two main factors: salinity and temperature. As pressure increases, density increases. As temperature increases, density decreases.

113. Water expands when it freezes. Water is densest at 4oC as a liquid. Ice at or below 0oC is less dense and floats.

114. Salinity is the total amount of substances dissolved in water. The most abundant salt in seawater is sodium chloride— common table salt. The average salinity of the world ocean is 3.5% or 35‰. Because the proportion of dissolved substances in seawater is such a small number, oceanographers typically express salinity in parts per thousand (‰).

115. Chemical weathering of rocks on the continents is one source of elements found in seawater. The second major source of elements found in seawater is from Earth’s interior.

116. The ocean’s surface water temperature varies with the amount of solar radiation received, which is primarily a function of latitude.

117. Oceanographers generally recognize a three layered structure in most parts of the open ocean: a shallow surface mixed zone, a transition zone, and a deep zone.

118. Marine organisms can be classified according to where they live and how they move. Three factors are used to divide the ocean into distinct marine life zones: the availability of sunlight, the distance from shore, and the water depth.

119. Near-shore food webs start with plants and protists (algae). Open ocean food webs generally begin with phytoplankton. Animals that feed in the deep sea mostly rely on scavenging the chemosynthesis. The transfer of energy between trophic levels is very inefficient.

Dynamic Ocean

120. The Coriolis Effect: due to the Earth’s rotation, currents are deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

121. Surface currents develop from friction between the ocean and the wind that blows across its surface.

122. Currents traveling away from the equator are warm. Currents traveling away from the poles are cold.

123. Upwelling brings greater concentrations of dissolved nutrients, such as nitrates and phosphates, to the ocean surface.

124. Most ocean waves obtain their energy and motion from the wind.

125. There are five main parts to any wave: wavelength, crest, trough, amplitude/height and resting point/sea level.

126. The height, length, and period that are eventually achieved by a wave depend on three factors: (1) wind speed; (2) length of time the wind has blown; and (3) fetch.

127. Circular orbital motion allows energy to move forward through the water while the individual water particles that transmit the wave move around in a circle.

128. Ocean tides result from the gravitational attraction exerted upon Earth by the moon and, to a lesser extent, by the sun.

129. Shoreline features originate primarily from the work of erosion. Sediment is transported along the shore and deposited in areas where energy is low produce depositional features.

Atmosphere

130. Temperature is the average kinetic energy (the energy of motion) of the molecules in a substance.

131. Conduction: energy transfer through molecular collisions; solids in contact. Convection: energy transfer through differences in density. Circulating currents of gasses and liquids. Radiation: energy transfer through space.

132. Energy moves from the source (highest temp.) to the sink (lowest temp.).

133. The atmosphere can be divided vertically into four layers based on temperature (troposphere, stratosphere, mesosphere, thermosphere).

134. Factors other than latitude that exert a strong influence on temperature include heating of land and water, altitude, geographic position, cloud cover, and ocean currents.

135. If ozone did not filter most UV radiation, Earth would be uninhabitable for many living organisms.

Moisture in the Atmosphere

136. When saturated, warm air contains more water vapor than cold air.

137. Relative humidity is a ratio of the air’s actual water vapor content compared with the amount of water vapor needed for saturation at that temperature and pressure.

138. Clouds are classified on the basis of their form and height. Fog is a cloud with its base at or very near the ground.

139. The type of precipitation that reaches Earth’s surface depends on the temperature profile in the lowest few kilometers of the atmosphere.

140. The closer the dew point temperature gets to the air temperature the greater the chance for precipitation.

141. Precipitation occurs when: warm, moist air rises, cools adiabatically (due to expansion), reaches the dew point temp., condensation occurs (on condensation nuclei), the droplets collect in masses (cloud formation) when the drops are large enough = precipitation.

142. [pic]

Air Pressure and Wind

143. As humidity (moisture content of the air) increases, air pressure decreases. As temperature increases, air pressure decreases. As altitude/elevation increases, air pressure decreases.

144. High Pressure = sinking air currents, dry conditions, little to no clouds.

145. Low Pressure = rising air currents, moist conditions, increase in cloud development.

146. Wind is the result of horizontal differences in air pressure. Air flows from areas of higher pressure to areas of lower pressure. The unequal heating of Earth’s surface generates pressure differences. Solar radiation is the ultimate energy source for most wind.

147. Three factors combine to control wind: pressure differences, the Coriolis Effect, and friction. These factors cause a net flow of air inward/convergent around a cyclone (counterclockwise) and a net flow of air outward/divergent around an anticyclone (clockwise).

148. The local winds are caused either by topographic effects or by variations in surface composition— land and water—in the immediate area.

149. Wind is named by the direction it is coming from.

Weather and Storms

150. Air masses are characterized by their temperature and moisture characteristics. When two air masses meet, they form a front.

151. [pic]

152. Polar (P) or tropical (T) indicates the temperature of an air mass. Continental (c) or maritime (m) indicates whether the air mass is dry or humid.

153. A thunderstorm generates thunder and lightning and frequently produces gusty winds, heavy rain, and hail. Thunderstorms form when warm, humid air rises in an unstable environment.

154. Tornadoes are violent windstorms that take the form of a rotating column of air called a vortex, which extends downward from a cumulonimbus cloud. Most tornadoes are associated with severe thunderstorms.

155. Hurricanes are whirling tropical cyclones with high winds that sometimes develop over the ocean when water temperatures are warm enough to provide the necessary heat and moisture to fuel the storms.

156. Weather moves from west to east (northeast trend) in the United States.

157. The oceans and the atmosphere balance differences in solar radiation in the tropics and the poles by acting as a giant heat-transfer system. This system moves warm air toward high latitudes and cool air toward the equator.

158. At irregular intervals of three to seven years, warm equatorial currents along the coasts of Ecuador and Peru become unusually strong and replace normally cold offshore waters with warm waters. This occurrence is referred to as an El Niño event.

159. When surface temperatures in the eastern Pacific are colder than average, a La Niña event is triggered that has a distinctive set of weather patterns.

Climate

160. Large bodies of water moderate coastal climates. Increases in latitude and increases in altitude have similar effects on climate.

161. Volcanic ash, dust, and sulfur-based aerosols in the air can cause a short-term cooling of the lower atmosphere.

162. Changes in the shape of Earth’s orbit and the tilt of Earth’s axis affect global climates.

163. The greenhouse effect is a warming of Earth’s lower atmosphere and Earth’s surface. As a result of increases in carbon dioxide levels (caused by human activity), as well as other greenhouse gases, global temperatures have increased to cause global warming. Global warming causes many changes to the planet including changes in sea level.

Origin of Modern Astronomy

164. In the geocentric model, the moon, sun, and the planets orbit Earth. Popularized by Ptolemy.

165. In the heliocentric model, Earth and the other planets orbit the sun. Proposed by many, proven by Copernicus.

166. Brahe’s observations, especially of Mars, were far more precise than any made previously. Using Brahe’s precise observations, Kepler discovered three laws of planetary motion.

167. Galileo described the behavior of moving objects. He made improvements to telescopes but did not invent them.

168. Newton was the first to formulate and test the law of universal gravitation.

169. People of all cultures have been studying the night sky for as long as humans have existed. The Greeks and Europeans simply did the best job of telling people about their ideas.

The Earth-Moon System

170. The earth rotates on its axis from west to east (counterclockwise). One Earth rotation takes approximately 24 hours. One hour equals 15o of rotation.

171. The earth revolves around the sun counterclockwise. One earth revolution takes 365.26 days in a slightly elliptical orbit.

172. The seasons are due to the tilt of the earth’s axis, 23½ o NOT its distance from the Sun. Earth is closer to the sun (perihelion) around January 3rd or 4th (winter).

173. Summer Solstice (June 21st) longest day of the year in the northern hemisphere – sunrise north of east. Winter Solstice (December 21st) shortest day of the year in the northern hemisphere – sunrise south of east.

174. Equinoxes (September 23rd) Autumnal and (March 21st) Vernal. 12 hours of daylight and 12 hours of darkness everywhere on earth. (Equinox means “equal night”.)

175. Hottest days of the year are usually 1-month after the day of maximum insolation, June 21st, “seasonal temperature lag”. Hottest time of any 24-hour period is usually 1 - 2 hours after noon (max insolation), “daily temperature lag”.

176. The equatorial region always has approximately 12 hours of daylight all year.  

177. The most widely accepted model for the origin of the moon is that when solar system was forming, a body the size of Mars impacted Earth.

178. The moon has phases because of the angle at which we view its surface. ½ the moon is always lit by the sun (we can only ever see 1 side of the moon). The moon’s phases take 29½ days to complete the cycle.

179. An eclipse can only occur during a new moon or full moon when the moon’s orbit crosses the plane of the ecliptic.

Our Solar System

180. The nebular hypothesis suggests that the bodies of our solar system evolved from and enormous rotating cloud of dust and gas (a nebula).

181. Planets appear to go backwards (retrograde) as Earth passes them in space.

182. All planets orbits are in the shape of an ellipse with the Sun at the focus point. The closer the planet is to the sun, the faster it travels in its orbit.

183. The terrestrial planets are rocky and found in orbits closest to our sun: Mercury, Venus, Earth and Mars.

184. The Jovian planets are primarily composed of gases and dust: Jupiter, Saturn, Uranus and Neptune.

185. Dwarf planets are small round objects in the solar system with weak gravitational fields and are not satellites. Pluto, Ceres and Eris are three of the largest.

186. Smaller Solar System Bodies: asteroids, meteors, comets and small objects orbiting the Sun.

Our Sun and Other Stars

187. Our local star’s name is Sol. It is a yellow star in the middle of its life cycle. The Sun’s energy drives many of the processes that occur in the atmosphere, hydrosphere and biosphere.

188. The sun can be divided into four parts: the solar interior; the visible surface, or photosphere; and two atmospheric layers, the chromosphere and corona.

189. Sunspots appear dark because of their temperature, which is about 1500 K less than that of the surrounding solar surface.

190. Prominences are ionized gases trapped by magnetic fields that extend from regions of intense solar activity.

191. Solar flares release enormous amounts of energy, much of it in the form of ultraviolet, radio, and X-ray radiation.

192. The nearest stars have the largest parallax angles, while those of distant stars are too small to measure.

193. Three factors control the apparent brightness of a star as seen from Earth: how big it is, how hot it is, and how far away it is.

194. Color is a clue to a star’s temperature. When the spectrum of a star is studied, the spectral lines act as “fingerprints.” These lines identify the elements present and thus the star’s chemical composition.

195. A Hertzsprung-Russell diagram shows the relationship between the absolute magnitude and temperature of stars.

196. When the core of a protostar has reached at least 10 million K, pressure within is so great that nuclear fusion of hydrogen begins, and a star is born.

197. Stars like the sun begin as a nebula, spend much of their lives as main-sequence stars, become red giants, planetary nebulae, white dwarfs, and finally, black dwarfs.

198. During nuclear fusion, energy is released because some matter is converted to energy.

199. All stars, regardless of their size, eventually run out of fuel and collapse due to gravity.

Beyond Our Solar System

200. The big bang theory states that at one time, the entire universe was confined to a dense, hot, super massive ball. Then, about 13.7 billion years ago, a violent explosion occurred, hurling this material in all directions.

201. In astronomy, the Doppler Effect is used to determine whether a star or other body in space is moving away from or toward Earth. The red shifts of distant galaxies indicate that the universe is expanding.

202. There are two main types of telescopes: optical and radio. Optical telescopes (reflecting and refracting) use lenses to produce images by bending light. They work best in space where the atmosphere cannot distort the images. Radio telescopes collect electromagnetic waves which are interpreted to produce images.

203. Galaxies are classified by their size, shape and the age of their stars. We live in the Milky Way Galaxy. It is a large spiral galaxy whose disk is about 100,000 light-years wide and about 10,000 light-years thick at the nucleus.

North Carolina

204. North Carolina’s population has changed from primarily rural and centered in small towns to primarily urban and suburban.

205. North Carolina has three regions – the Coastal Plain, the Piedmont, and the Blue Ridge Mountains.

206. The Eastern Continental Divide runs through the Blue Ridge Mountains. All groundwater East of this point drains into the Atlantic Ocean. All groundwater west of this point drains into the Gulf of Mexico.

207. Raleigh in located in the Neuse River basin which drains to the Atlantic ocean.

208. The fall line is a zone where streams and rivers fall in rapids and waterfalls from the Piedmont to the Coastal Plain.

209. The Appalachian Mountains, which include the Blue Ridge and Great Smokey Mountains, occupy the western end of North Carolina. These mountains formed as the African and North American plates collided to create Pangea.

210. Erosion has shaped the mountains into the landforms they are today. Sediment eroded from the mountains to help form the Coastal Plain.

211. North Carolina has an abundance of natural resources including mineral resources, forests and fisheries

212. North Carolina is located in the temperate deciduous forest biome, which includes many ecosystems.

213. North Carolina has over 300 types of soil. Most of our soils are acidic and subject to leaching.

214. Freshwater resources in North Carolina include surface streams, rivers, lakes and aquifers.

215. Wetlands protect coastal areas from flooding, filter pollution from runoff before it enters streams and aquifers, and serve as a natural habitat. Many of North Carolina’s wetlands have been drained and filled, but there are now efforts to protect wetlands.

216. Coastal development has caused crowding, pollution and loss of natural wildlife habitat.

217. National seashores and other preserves protect large areas of North Carolina’s Atlantic Coast.

218. North Carolina has a humid, moderate climate of hot summers and short, mild winters. Distance from the coast and differences in elevation cause local variations in climate.

219. North Carolina experiences several types of severe weather, including hurricanes, tropical storms, tornadoes, floods, and winter storms.

220. Significant threats to North Carolina’s environment include air pollution, acid rain, poorly managed fisheries, groundwater depletion and pollution, and rising sea levels due to global warming.

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