Could Volcanoes Power Our Planet? And More Questions From Our Readers

Could we use volcanic energy as a power source? Henry C. Petersen | Granite Bay, California

There is certainly a lot of energy when a volcano erupts—and I do mean a lot. As an example, the thermal energy released during the 1980 eruption of Mount St. Helens was enough to power the entire world for about two and a half days. Unfortunately, we cannot capture that energy. But we can capture some of the geothermal energy from magma cooling underground. In places where cooling magma is close enough to the Earth’s surface, we can drill wells and then circulate the hot water to either heat buildings directly or generate electricity. Areas with active volcanoes—Iceland, the United States, New Zealand, Indonesia, Mexico, Japan, Kenya—tend to be places that have geothermal power. —Ben Andrews, director of the Global Volcanism Program, National Museum of Natural History

What’s the minimum number of geese needed for an aerodynamic advantage? Jennifer Harvey | Sandpoint, Idaho

Even two geese flying together can benefit from aerodynamics. They can switch their positions, taking turns helping each other by creating air currents. When a flock has three or more members, it can form a V, where each bird helps the birds behind it by creating an upward force of air called “upwash.” This dynamic has no maximum number—it’s more a matter of the need for geese to maintain contact within their flock. It’s harder for larger flocks to stay together, as anyone who’s traveled in big groups can tell you. —Sarah Luttrell, researcher of birds and vertebrate zoology, National Museum of Natural History

What was the landscape like around the Great Pyramids when they were built? Craig Westbrooke | Albany, California

Much has changed in the 4,500 to 4,600 years since the Great Pyramid, the Great Sphinx, the Pyramid of Khafre and the other monuments at Giza were constructed. This was at the beginning of a drying phase that began about 5,000 years ago, so rainfall probably was much greater than in today’s desert climate, and the annual floods of the Nile, now mostly suppressed by the Aswan Dam, were typically much higher. The monuments were constructed on the very edge of the Giza Plateau overlooking the Nile River and well above its floodwaters. I do not know of any studies that address the appearance of this area at that time, but the natural vegetation might have been grassland or shrubland. Given the religious and political nature of the site, it may have been landscaped to enhance the visual impact of the monuments. —Neal Woodman, research associate, National Museum of Natural History

What was the reason for using an “f” instead of an “s” in old typefaces? Seth Boyes | Spirit Lake, Iowa

The letter resembling the “f” was really the long “s.” (Unlike an “f” it had a crossbar only on the left side.) The long “s” was used in cursive handwriting and, when the printing press was invented in the mid-15th century, it carried over into printed texts. The round “s” we use today was reserved for the ends of words. By the late-1700s, the long “s” fell out of favor, it is assumed, to assist a growing population of middle-class readers who found the letter confusing and to make things simpler for the typesetters themselves. —Joan Boudreau, curator of graphic arts, National Museum of American History