X-rays on the skies
National Capital Astronomers, Nov. 10 meeting

The National Capital Astronomers will gather Saturday for a presentation on dark matter, galaxy clusters and what X-rays can reveal about these cosmological wonders. Michael Loewenstein, a research scientist at NASA’s Goddard Space Flight Center and an astronomy instructor at the University of Maryland at College Park, will lead the talk. The event, free and open to the public, will be held at 7:30 p.m. at the university’s astronomical observatory. The club also holds monthly stargazing sessions between April and November, opportunities worth marking on your 2013 calendar.

They might have been giants
“Once & Future Giants,” by Sharon Levy

“We live surrounded by the ghosts of giants.” So begins Sharon Levy’s book, which dusts off the fossils of mastodons that once foraged in Manhattan, mammoths that once thumped down L.A.’s Wilshire Boulevard and bear-size beavers once found in streams across North America. “Once & Future Giants,” new in paperback, delves into the history of “megafauna” extinctions and examines the role that humans played in wiping out many of the Ice Age’s large-animal species.

Despite long-held assumptions that blamed a warming climate for the giants’ decline, Levy found that new research points to human culpability through hunting (which Levy refers to as “overkill”) and habitat destruction.

Why should we care about these ancient extinctions? “Twenty-first century people need to understand the mammoth and the saber-toothed cat, not to raise musty bones from the dead but to help keep alive what wildness we still have with us,” writes Levy, pointing to elephants and polar bears as examples. Research shows the greatest risk to megafauna today isn’t hunting or habitat destruction, thanks to conservation efforts. Rather, it appears to be climate change, which threatens humans — regarded by some scientists as modern megafauna — as well as wild animals.

Maggie Fazeli Fard