March 15, 2012
Readers questions continue this month with some really intriguing queries. Can you identify a bird just by its feather? The aptly named Carla Dove, a Smithsonian ornithologist weighs in on that one in the video above. And speaking of our fine feathered friends, another reader wonders why it is that birds all seem to want to hang out near electrical transformers? From dinosaurs to telescopes to gemstones, you asked and we found the answers.
Are there any paleontological discoveries, such as dinosaur bones, left to be made in the United States?
Susanne Ott, Bern, Switzerland
There sure are. This is such a large country, and there are so many areas yet to be searched, that we may not run out of finds for several lifetimes. Just think: We have found only about 2,000 species of dinosaurs for the 160 million years they were alive on Earth. Given that a species lasts only a few million years, we must be missing many thousands of dinosaur species. The most promising places are out West, where it’s drier and paleontologists can get access to fossil-bearing rocks.
Matthew Carrano, Paleontologist
Museum of Natural History
How much artistic license do scientists use when they portray astronomical features detected by radio telescopes?
Jeanne Long, Atlanta, Georgia
A lot, actually. Radio-telescope images differ from the images captured by the Hubble Space Telescope—while Hubble images are recorded in the visible wavelengths of light we see in rainbows, radio telescopes record electromagnetic radio waves sent out by distant galactic objects. They detect what our ears might pick up if we could hear the universe. (Luckily, we can’t, or the world would be a jumbled mess of rumbling sounds.) Based on the intensity of the radio waves, astronomers plot signal strengths and assign different colors to them.
Although it would be handy and logical, there is no set convention to those color assignments. Scientists choose different colors to bring out specific details or molecules found in the image. (If you do a quick Google image search for the Trifid Nebula, you’ll see images with different color representations of the same object.) Is it fair to randomly assign different colors to objects in space? To astronomers, that’s not an issue. They are simply trying to isolate data. And the truth is, the human eye is not sensitive enough to pick up the true colors of these objects anyway. So, the next time you see a breathtaking picture from space, thank a scientist for putting it all together.
David Aguilar, Astronomer and illustrator
Smithsonian Astrophysical Observatory
Is it true that the Smithsonian is still cataloguing items from Charles Wilkes’ United States Exploring Expedition?
Kevin Ramsey, Washington, D.C.
That expedition returned from its four-year exploration of the Pacific in 1842 with an immense trove—hundreds of fish and mammal specimens, more than 2,000 bird specimens, 50,000 plant specimens, a thousand live plants, some 4,000 ethnographic objects, such as Fijian war clubs, Samoan fish hooks and New Zealand baskets. But no, the Smithsonian is not still cataloguing them. That job largely fell to the scientists who accompanied Wilkes, and they completed it, well, expeditiously. The collection was exhibited in the Patent Office Building in Washington, D.C. for several years, before it came to the Smithsonian.
Pamela M. Henson, Historian
Smithsonian Institution Archives
Did Mathew Brady really take all the Civil War photographs that are credited to him?
Patrick Ian, Bethesda, Maryland
No. By 1861, Mathew Brady was one of the best-known photographers in America, with portrait studios in New York City and Washington, D.C. While his staff handled day-to-day operations, Brady provided the creative vision and marketing expertise that made his studios famous. When the Civil War began, he assembled and outfitted teams of photographers and sent them into the field to ensure that his cameras would be present to produce a visual record of the conflict. Although Brady traveled periodically to battlefields and encampments, the Civil War photographs that carry his credit line were typically made by his cameramen. The look of the portraits produced in Brady’s studios—such as those featured in the National Portrait Gallery’s new exhibition, Mathew Brady’s Photographs of Union Generals (March 30, 2012-May 31, 2015)—reflected his aesthetic even when he was not present for the portrait session.
Ann M. Shumard, Curator of Photographs
National Portrait Gallery
Why do birds like to congregate around electric transformers?
Luis Tewes, Palm Beach Gardens, Florida
While the ever-growing electrical grid spells trouble for most species of birds, some have incorporated human structures into their lives. Power lines are a flight hazard to many species, but they also provide elevated perches, particularly in open country where there are few natural alternatives, for sit-and-wait predators, such as bluebirds, shrikes and small raptors. Many species use electric lines to rest or monitor their territories; and flocks of blackbirds and starlings and other birds gather on wires before they join large communal roosts. Power-line poles and towers and their attendant transformers provide additional support and protection for flocks and larger species, such as raptors. A few species even commandeer power poles and transformers as nesting sites. Transformers may produce some heat, which may explain why some birds like them. The monk parrakeet, introduced from Argentina, nests and roosts around transformers and has expanded into some pretty cold urban areas.
Birds’ use of power equipment illustrates their impressive adaptability, but awareness of high-voltage electric currents is not in their DNA. While a bird can perch on a high-voltage line in complete safety, as soon as it makes secondary contact with a conductor that leads to a ground, it will be fried. Large birds taking flight or producing “streamers” of fecal material often complete the circuit to their demise. Fecal build-up, gnawing (by parrots) and nesting material can short out lines or transformers, leading to massive power outages. Bird mortality might be reduced, and electrical service might be more reliable, if we had a better-designed grid.
Russell Greenberg, Wildlife Biologist,
Migratory Bird Center, National Zoo
In aserated (or “starred”) gemstones, such as the ruby and sapphire varieties of corundum, what is the average amount of rutile per square millimeter? And how many asterated gemstones does the Smithsonian Institution have?
Davis M. Upchurch, Fletcher, North Carolina
In synthetic asterated corundum, about 0.1 to 0.3 percent titanium oxide is typically mixed with the aluminum oxide. That gives you a ballpark idea as to the fraction of rutile (which is usually given as an amount per cubic millimeter). The Museum of Natural History has about 50 asterated gems in its collection, including, 21 specimens of corundum. We add new ones sporadically, and we’re always on the lookout for different or better examples.
Jeffrey Post, Curator of Gems and Minerals,
Museum of Natural History
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