Nature Facts

How far does regular dust blow in the wind?
A 1999 study showed that African dust finds its way to Florida and can help push parts of the state over the prescribed air quality limit for particulate matter set by the U.S. Environmental Protection Agency. The dust is kicked up by high winds in North Africa and carried as high as 20,000 feet (6,100 meters), where it's caught up in the trade winds and carried across the sea. Dust from China makes its way to North America, too.

How much space dust falls to Earth each year?
Estimates vary, but the USGS says at least 1,000 million grams, or roughly 1,000 tons of material enters the atmosphere every year and makes its way to Earths surface. One group of scientists claims microbes rain down from space, too, and that extraterrestrial organisms are responsible for flu epidemics. There's been no proof of this, and I'm not holding my breath.

Can rocks grow?
Yes, but observing the process is less interesting than watching paint dry. Rocks called iron-manganese crusts grow on mountains under the sea. The crusts precipitate material slowly from seawater, growing about 1 millimeter every million years. Your fingernails grow about the same amount every two weeks.

Can rocks float?
In a volcanic eruption, the violent separation of gas from lava produces a "frothy" rock called pumice, loaded with gas bubbles. Some of it can float, geologists say. I've never seen this happen, and I'm thankful for that.

What is the coldest place on Earth?
Far and away, the coldest temperature ever measured on Earth was -129 Fahrenheit (-89 Celsius) at Vostok, Antarctica, on July 21, 1983.

What is the hottest place on Earth?
Count one wrong if you guessed Death Valley in California. True enough on many days. But El Azizia in Libya recorded a temperature of 136 degrees Fahrenheit (57.8 Celsius) on Sept. 13, 1922 -- the hottest ever measured. In Death Valley, it got up to 134 Fahrenheit on July 10, 1913.