What is the Daily Rainfall on Earth and More Questions From Our Readers

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Illustration by Cassandre Montoriol

Why do some flowers bloom only at night?
Marcia K. Sicree
Boalsburg, Pennsylvania

A flower’s shape, color, scent, pollen and nectar are adapted to attract a very specific pollinator; flowers that open at night do so to attract nocturnal creatures, such as bats, moths and rodents. The botanical term for the movement of leaves and petals in response to darkness is “nyctinasty.”
Barbara Faust
Horticulturist, Smithsonian Gardens

What is gravity like at the center of the earth?
John Crumpacker
Silver Spring, Maryland

The earth is nearly a perfect sphere; at its center the gravitational force is equal in every direction. Therefore you would feel weightless—provided you could survive the scorching temperatures and crushing pressures there.
David Kipping
Planetary scientist, Harvard-Smithsonian Center for Astrophysics

How do people living in the Arctic, with so few edible plants, get vitamin C to prevent scurvy?
Vivian Davis
Surrey, British Columbia, Canada

The traditional diet of Inuit living in the Canadian Arctic was relatively rich in vitamin C. Caribou, whale and seal meat, especially the liver, skin and brains, have lots of it; so do the berries—blueberries, crowberries, redberries and cloudberries—that grow in summer and fall. However, many Inuit families no longer eat the diet of their ancestors, preferring processed and manufactured foods from the south. One result is high rates of diabetes in young people.
Stephen Loring
Anthropologist, Arctic Studies program, National Museum of Natural History

Is it true that the money James Smithson donated to the United States was deposited in an Arkansas bank that went broke, and that Congress appropriated money to replace it?
Omar D. Smith
Russellville, Arkansas

No. After the Smithson bequest was received, in 1838, the U.S. Treasury invested it in the bonds of several states. When the Smithsonian Institution was created, in 1846, the bonds had not yet paid up, so the Treasury swapped the bonds for Treasury funds. Most of the bonds later paid out to the Treasury in full, so the funds were not lost.
Pamela Henson
Historian, Smithsonian Institution Archives

What is the average daily rainfall on earth, and how do you find that
Mark Jones
Philadelphia, Pennsylvania

The average global rainfall is a little over two millimeters (.08 inches) per day. This global average includes heavy tropical rains and vast arid deserts. The joint U.S.-Japan Tropical Rainfall Measuring Mission satellite has been measuring rainfall since 1997, and other satellites have since been included in a system to measure global precipitation. Other efforts have used networks of land-based gauges.
Andrew Johnston
Geographer, National Air and Space Museum

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Illustration by Cassandre Montoriol

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