How Do Scientists Record Sounds From the Sun? And More Questions From Our Readers

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Sun Illustration
Oscillations originating deep inside the sun become detectable only on the surface. Illustration by John Hersey

Q: I understand that scientists record noises from the sun, but I thought sound didn’t travel in a vacuum. How do they record these sounds?

— Frederick Vogt | Grand Rapids, Michigan

You’re right: Sound waves cannot travel in a vacuum. But scientists who study the dynamics of the sun’s interior convert other kinds of signals into audio files, explain the National Air and Space Museum’s David DeVorkin and Shauna Edson. Oscillations originating deep inside the sun become detectable only on the surface, at which point scientists use optical, spectroscopic and radio instruments to measure the phenomena. Those readings are then converted into sound waves to help the scientists analyze and find patterns in the data.

Q: The National Museum of Natural History features a giant prehistoric millipede. Why is it so much bigger than today’s millipedes?

— Anonymous

There are two hypotheses to explain why this land-dwelling myriapod, which measured over six feet, thrived some 300 million years ago, says Conrad Labandeira, curator of fossil arthropods at the National Museum of Natural History. Gigantism also affected protodonatan dragonflies, which were predatory aerial insects and had wingspans approaching 30 inches. One explanation for gigantism in both land and aerial arthropods at that time was the absence of predators. The other explanation is the higher concentration of oxygen in the atmosphere—140 to 170 percent higher than levels today. The latter explanation would have given these arthropods greater respiratory efficiency than their modern counterparts that, in turn, led to larger sizes.*

Q: Why do American drivers sit on the left side of the car and drive on the right side of the road?

— Michael Reed | Allegan, Michigan

In 1792, on its newly established turnpike, Pennsylvania required buggy or wagon drivers to keep right. About a decade later, New York became the first state to mandate right-hand travel on all public highways. As automobiles became more common at the turn of the 20th century, safety proponent William Phelps Eno wrote the world’s very first traffic code, adopted by New York City in the early 1900s. For the first decade or so of the automobile era, many cars had the steering wheel on the right-hand side. Historians believe that’s because it was easier for drivers to keep an eye on ditches and the sides of narrow bridges they might be crossing, says Roger White, curator of road transportation at the National Museum of American History. That changed with the Ford Model T, which moved the steering wheel to the left. The 1909 brochure cited two benefits: letting a passenger exit at the curb and giving the driver a better view of oncoming traffic. Other automakers were inspired to follow suit when the Model T quickly became the best-selling car of the era.

Q: Why do male lions have manes growing around their ears? What does this mean in the animal kingdom?

— Jeaneth Larsen | Mitchell, South Dakota

It could be for protection, mate selection or both. Male lions fight other lions, hyenas and other smaller predators for territory, food and the right to stay in the pride, explains Craig Saffoe, curator of the Great Cats area at the National Zoo. Their manes, which are very thick and extend to cover their necks, provide crucial protection, almost like medieval chain mail. Also lionesses may be attracted to healthy manes, and may even have preferred colors. The mane may serve a similar purpose to the tail feathers male peacocks use to attract mates.

It’s your turn to Ask Smithsonian.

*Editor's Note, February 25, 2020: In an earlier version of this piece, we incorrectly referred to the six-foot-long arthropleurids, the so-called “prehistoric millipedes,” as insects. Instead, extinct arthroplelurids and modern millipedes are classified as myriapods. Both myriapods and insects are subgroups of arthropods. The story has also been expanded to talk about protodonatan dragonflies.

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