71. How many lightning strikes occur worldwide every second?
On average, about 100. Those are just the ones that hit the ground, though. During any given minute, there are more than a thousand thunderstorms around the Earth causing some 6,000 flashes of lightning. A lot of it goes from cloud-to-cloud.
72. Are rivers alive?
Not in the traditional sense, of course. But like all living creatures, rivers have a life span. They are born, grow in size, and they age. They can even die during the span of geological time.
73. Can asteroids create islands?
Speculation has existed for decades that ancient asteroid impacts might create hot spots of volcanic activity, which could give rise to mountains that poke up through seas that didn't used to be there. There's no firm answer to this question, but a recent computer model suggested Hawaii might have been formed in this manner.
74. Is the state of Louisiana growing or shrinking?
Louisiana loses about 30 square miles (78 square kilometers) of land each year to coastal erosion, hurricanes, other natural and human causes and a thing called subsidence, which means sinking. Much of New Orleans actually sits 11 feet (3.4 meters) below sea level. Parts of the French quarter have sunk 2 feet in the past six decades. The city is protected by dikes, but all experts agree that storm tides from a direct hit by a major hurricane would breach the system and swamp much of the city. In 2000, the director of the U.S. Geological Survey, Chip Groat, said: "With the projected rate of subsidence, wetland loss and sea-level rise, New Orleans will likely be on the verge of extinction by this time next century."
75. How much would seas rise if the Antarctic Ice Sheet melted?
The Antarctic Ice Sheet holds nearly 90 percent of the world's ice and 70 percent of its fresh water. If the entire ice sheet were to melt, sea level would rise by nearly 220 feet, or the height of a 20-story building. Scientists know there's a melting trend underway. The United Nations has said that in a worst-case scenario -- depending on how much global air temperatures increase -- seas could jump 3 feet (1 meter) by 2100.
77. Is ice a mineral?
Yes, ice is a mineral and is formally described as such in Dana's System of Mineralogy.
77. What is the softest of all minerals?
Talc is the softest of minerals. It is commonly used to make talcum powder.
78. What is the hardest of all minerals?
The one that becomes emotionally useless after a divorce but still retains monetary value.
79. How are colors produced in fireworks?
Mineral elements taken from Earth provide the colors. Strontium yields deep reds, copper produces blue, sodium yields yellow, and iron filings and charcoal pieces produce gold sparks. Bright flashes and loud bangs come from aluminum powder.
80. Does Earth have the worst weather in the solar system?
Right now, it's the worst that most humans I know ever experience. But there's lots of wilder weather elsewhere. Mars can whip up hurricane-like storms four times bigger than Texas. Dust storms on the red planet can obscure the entire globe! Jupiter has a hurricane twice the size our entire planet, and it's lasted for at least three centuries (another storm on Jupiter is even bigger). Venus is a living hell, and Pluto is routinely more frigid than the coldest place on Earth (though may change one day, and Pluto may in fact become the last oasis for life).
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