Amazing Earth Facts - XII

67. What is the world's largest island?

Greenland covers 840,000 square miles (2,176,000 square kilometers). Continents are typically defined as landmasses made of low-density rock that essentially floats on the molten material below. Greenland fits this description, but it's only about one-third the size of Australia. Some scientists call Greenland an island, others say it's a continent.

Moon making

68. Where are most of Earth's volcanoes?

The most prominent topographic feature on Earth is the immense volcanic mountain chain that encircles the planet beneath the sea -- the chain is more than 30,000 miles (48,000 kilometers) long and rises an average of 18,000 feet ( 5.5 kilometers) above the seafloor. It is called the mid-ocean ridge and is where Earth's plates spread apart as new crust bubbles up -- volcanic activity. There are more volcanoes here than on land. The spreading, however, leads to scrunching when these plates slam into the continents. The result: More volcanoes and earthquakes in places like California and Japan.

69. What volcano killed the most people?

The eruption of Tambora volcano in Indonesia in 1815 is estimated to have killed 90,000 people. Most died from starvation after the eruption, though, because of widespread crop destruction, and from water contamination and disease.

70. Were Earth and the Moon separated at birth?

Not quite. But leading theory holds that our favorite satellite was carved partly from Earth shortly after the Earth formed. A Mars-sized object slammed into our fledgling planet. The impactor was destroyed. Stuff flew everywhere and a lot of it went into orbit around Earth. The Moon gathered itself together out of the largely vaporized remains of the collision, while Earth hung in there pretty much intact.

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.