1. Can Rocks float? A. 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.
2. Can Rocks grow? A. 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.
3. How much space dust falls to Earth each year? A. Estimates vary, but the USGS says that at least 1,000 million grams or roughly 1,000 tons of material enters the atmosphere every year and makes its way to Earth’s 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.
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