Q: What would happen if the earth suddenly stopped rotating?

— Roy Arvio | Chicago, Illinois

It wouldn’t be good. At the Equator, the earth’s rotational motion is at its fastest, about a thousand miles an hour. If that motion suddenly stopped, the momentum would send things flying eastward. Moving rocks and oceans would trigger earthquakes and tsunamis. The still-moving atmosphere would scour landscapes. But not to worry: Such an event would require the same amount of energy stored in the momentum of everything on our rotating planet, says Jim Zimbelman, a geologist in the Center for Earth and Planetary Studies at the National Air and Space Museum, and no physical mechanism on earth can supply that.

Q: Were there ever monkeys native to North America?

— Jim Skvorc | Dolores, Colorado

It appears not. Monkeys appeared in Africa during the Oligocene era, which ended 23 million years ago, and then in South America just a few million years later, says Emily Early, a research associate of the National Museum of Natural History’s Human Origins Program. But until about three million years ago, North and South America were separated by an ocean, and even after the Isthmus of Panama formed, the tropical forests where the South American monkeys had evolved did not exist farther north. Some populations may have tried moving northward, but not in large enough numbers to take hold.

Q: Was there an Ellis Island equivalent on the West Coast, some central processing place for immigrants?

— Edwin Crammer | Sunrise, Florida

Yes: Angel Island Immigration Station in San Francisco processed about a million immigrants, most of them from Asian countries, from 1910 to 1940. But it wasn’t like Ellis Island, where immigrants from Europe were greeted by the Statue of Liberty and generally passed through in hours. Angel Island was built primarily to enforce the Chinese Exclusion Act of 1882, which barred almost all immigrants from China, and the center subjected new arrivals to intense interrogations and invasive medical exams. Some 175,000 Chinese were detained there, sometimes for years, and many of them wrote poignant notes and poems on the walls, says Theodore S. Gonzalves, a curator at the National Museum of American History. A fire destroyed the administration building in 1940; it wasn’t rebuilt. Lower immigration rates, improving U.S.-China relations and repeal of the Exclusion Act in 1943 meant Angel Island was no longer needed.

Q: Who was the first person commemorated on a U.S. postage stamp?

— Wallis Kelner | Rockville, Maryland

Benjamin Franklin, the first postmaster general, and George Washington appeared on the five- and ten-cent stamps, respectively, when national postage stamps made their debut, in 1847. Before that, letter recipients were expected to pay the postage. But social reformers saw affordable postal service as the “social media of the 1830s and 1840s,” says Daniel Piazza, curator of philately at the National Postal Museum, and pushed for upfront payment. Stamps stemmed post office losses on unpaid letters, leading to cheaper rates and more letter-sending.

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