Q: We’ve successfully sent humans to the Moon, and there’s talk of sending people to Mars. How about Venus?
—Alan E. Wright | Salt Lake City
Landing on Venus is challenging enough for robotic missions, says Bruce Campbell, a senior scientist at the National Air and Space Museum. The temperature at the planet’s equator averages 880 degrees Fahrenheit and the atmospheric pressure is 90 times the pressure on Earth. While there are no imminent plans to send people to Venus, scientists are eager to learn more about Earth’s neighbor, says Campbell, who recently led a team in mapping a large part of Venus’ surface. For instance, if Venusian rocks formed in the presence of water, that might suggest the planet was once able to support life. Learning more about how Venus’ evolution diverged from Earth’s may help us understand how other planets formed.
Q: Do kangaroos have bellybuttons?
—Robert Roesch | Louisville, Colorado
They do not. Nor does any marsupial, explains Steve Sarro, curator of the small mammal house at the National Zoo. One defining trait of marsupials is that they’re non-placental, which means there is no umbilical cord delivering nutrients. Instead, the fetus is suspended in a yolk in one of the mother’s two uteruses for about a month. Then the joey uses its strong arms to climb from the base of the birth canal into its mother’s pouch, where it nurses and continues to develop for several more months. During this time, the joey grows hair, opens its eyes and pokes its head out to see the world for the first time. Eventually, it starts to wander outside of the pouch and strengthen its muscles, but will jump back in if it feels frightened. Mothers often have two joeys in a row: one outside of the pouch but still nursing, and another inside the pouch.
Q: It takes so much effort to keep our teeth healthy, but ancient teeth have survived inside skulls long after other body parts have decayed. Why is that?
—Erik Bailey | Vallejo, California
When teeth are buried and left alone, they’re durable and resilient, says Douglas Owsley, head of biological anthropology at the National Museum of Natural History. Also, pre-agricultural humans generally had less tooth decay than modern ones do because their diets contained less sugar. Anthropologists can get a lot of information from the condition of these ancient teeth, such as how people prepared their food, and which other groups on the globe shared their DNA.
Q: When did the war of 1914-18 begin to be called the Great War?
—Jack Rayl | Springfield, Missouri
Almost as soon as the conflagration began. The Canadian magazine Maclean’s noted, “Some wars name themselves. This is the Great War” in October 1914. Winston Churchill broke with British nomenclature when he called the conflict “the World War” in 1927, says David Ward, a senior historian emeritus at the National Portrait Gallery. Most British people stuck with “the Great War” into the late 1940s, calling the more recent global conflict “the War.” In contrast, Time magazine started using the terms World War I and World War II in 1939, before the United States entered the conflict.
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