NASA says ice coverage is increasing in Antarctica. How is this possible with global warming?

Kimmis Brady | Santa Ynez, California

As global average temperatures rise, not all parts of the planet will see the same effects, says Andrew Johnston, geographer at the Air and Space Museum. Some areas can even see cooling periods. Last year, the warmest on record, Antarctica had the most ice coverage it’s had in 30 years. Yet the Arctic Ocean is losing ice cover almost three times faster than the Antarctic is gaining it. Possible causes for the temperature differences involve changes in snowfall, winds and ocean circulation patterns.

What is the origin of the term “Jim Crow era” or “Jim Crow laws”?

Karen Kegg | Santa Barbara, California

Jim Crow was a fictional character developed in the late 1820s by the white entertainer Thomas D. “Daddy” Rice, who said he was inspired by an elderly black man singing a song titled “Jump Jim Crow,” says Bill Pretzer, senior history curator at the National Museum of African American History and Culture. After Rice became internationally known for performing the dimwitted, enslaved black character, “Jim Crow” became a derogatory term for African-Americans. In the 1870s and ’80s, it was applied to anti-black laws and practices in the South. The phrase “Jim Crow law” appeared in print as early as 1892, in the New York Times.

Did any pre-Columbian Native American tribes dig wells?

Dennis Perry | Soda Springs, Idaho

Yes, Native American peoples dug wells thousands of years ago, according to Dennis Stanford, anthropologist at the Museum of Natural History, who helped excavate a well in New Mexico dating back some 13,500 years—the oldest well found in the Americas. Evidence of pre-Columbian wells has been found elsewhere in New Mexico and in Texas.

I’ve read that the earthworm is not indigenous to the United States. Is that true?

Molly Chatterton | Shaftsbury, Vermont

No. Earthworms are native to the United States, says Melissa McCormick, ecologist at the Smithsonian Environmental Research Center, but the earthworms in some northern parts of the country (including Vermont) aren’t indigenous. Thousands of years ago, glaciers that covered North America and reached as far south as present-day Illinois, Indiana and Ohio wiped out native earthworms. Species from Europe and Asia, most likely introduced unintentionally in ship ballast or the roots of imported plants, have spread throughout North America.

Science fiction movies often show spacecraft with flames shooting from their engines. Is that possible, given the lack of oxygen in space?

Jeffry Harris | Rancho Santa Margarita, California

Actually, it is. The flame that comes out of the engine nozzle is the result of the combustion of liquid fuel (typically kerosene or hydrogen) and liquid oxygen stored in tanks in the spacecraft, says Tom Lassman, curator at the Air and Space Museum. Combustion produces thrust, which propels the craft and is visible as a bright flame.

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