Why Are Starfish Shaped Like Stars and More Questions From Our Readers

You asked, we answered

One of this issue's questions is about the starfish's namesake shape. Illustration by Melissa Washburn

Q: Why are starfish shaped like stars?

— Bonnie Hao | Beijing, China

Scientists can’t pinpoint exactly why starfish evolved to have radial symmetry, with arms—usually five, but as many as 40 in some species—growing from a central axis. However, Dave Pawson, emeritus senior scientist at the National Museum of Natural History, notes that the arrangement confers certain advantages on the animals (which, lacking a backbone, aren’t technically fish). At the tip of each arm is an eye that can detect changes in light intensity, and on the bottom are tube feet that enable it to move in any direction. Several species of starfish can regenerate an arm lost to a predator or an accident, and a few can even regenerate a new central disc from a severed arm, as long as a fragment of the disc remains with the arm.

Why were teachers colleges called “normal schools”?

— Lisa Frank | Los Angeles

Thank France; the phrase is derived from “école normale,” which was used for institutions designed to instill standards of pedagogy and curriculum in teachers-to-be, says Debbie Schaefer-Jacobs, associate curator in the Division of Cultural and Community Life at the National Museum of American History. America’s first state-sponsored normal school opened in Massachusetts in 1839, at the urging of public-education champion Horace Mann; it is now Framingham State University. More arose through the mid-19th century, in parallel with the development of public schools, then called “common schools.” By the 1930s, however, most normal schools were calling themselves “teachers colleges.”

The night skies of the Northern and Southern Hemispheres have different constellations. Can you see that difference as soon as you cross the Equator?

— Ethan Johnson | Washington, D.C.

No, says Rebecca Ljungren, an astronomy educator at the National Air and Space Museum. The differences become more apparent as you get farther from the Equator (or closer to the North or South Pole). Depending on the time of year or your latitude, you can still see many of the same constellations in either hemisphere. At the Equator, you can see all parts of the sky if you’re patient. The Southern Cross and the North Star will be really low on the horizon and hard—but not impossible—to spot.

I’ve heard that all kinds of artists used to live at Carnegie Hall. Is that true?

— Cynthia Yount | Fullerton, California

It is. Shortly after the hall was built, in 1891, two towers containing 170 rental studios were added. They provided the hall with an additional source of income and artists a place to live and work. Through the 20th century, the residents made up a remarkably vibrant community of musicians, dancers and painters, says Jennifer Cohlman Bracchi, a reference librarian at the Cooper Hewitt, Smithsonian Design Museum. Among the better-known tenants were Leonard Bernstein, Marlon Brando and the fashion photographer Bill Cunningham. The last renters were evicted in 2010 as the Carnegie Hall Corporation moved to renovate the towers into spaces for archival storage, teaching and rehearsal.

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