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BEAUTIFUL: A cloud of dust and gas ejected from the Boomerang Nebula.
NASA/Associated Press
BEAUTIFUL: A cloud of dust and gas ejected from the Boomerang Nebula.

Milky Way compass

Science | Planetary nebulae surprise by aligning themselves along the galaxy’s plane

Issue: "Bright or rotten idea?," Oct. 5, 2013

“The heavens declare the glory of God, and the sky above proclaims his handiwork,” Psalm 19 asserts. The latest mystery from the heavens involves the arrangement of beautiful gas clouds emitted by collapsing stars. Discovered in the 18th century, these stellar displays were misnamed “planetary nebulae” because of how they looked in early telescopes.

Some planetary nebulae are known as butterfly nebulae because their gas clouds flare out only at the poles of the host stars, giving them an appearance like a butterfly or hourglass. Now, astronomers studying our galaxy, the Milky Way, have discovered that butterfly nebulae tend to be unexpectedly aligned with the plane of the galaxy. Viewing our flying saucer–shaped galaxy on edge, many of these nebulae would look like hourglasses lying on their sides, rather than pointing at random angles. They are more likely to be aligned if they are located near the galaxy’s central bulge.

The surprising pattern occurs even though individual nebulae lie light-years apart and were thought to have unique histories. The astronomers, who wrote about the phenomenon in Monthly Notices of the Royal Astronomical Society, believe an extinct magnetic field in the Milky Way arranged the butterfly nebulae in their current configurations. Other types of planetary nebulae, which have an elliptical shape, do not exhibit the same alignment. All visible planetary nebulae are thought to be no more than 10,000 years old.

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Baby rate

Ron Jenkins/Fort Worth Star-Telegram/MCT/Getty Images

A four-year drop in the American birth rate has finally leveled, according to preliminary data from the Centers for Disease Control and Prevention. The agency says the 2012 fertility rate stood at exactly 63 births for every 1,000 women ages 15 to 44, just slightly lower than the year before. It follows a sharp 9 percent decline in the birthrate between 2007 and 2011, which demographers attribute to the recession.

The American fertility rate may be at its lowest in history (reliable recordkeeping only began in the 1920s). The rate dipped drastically during the Great Depression and peaked in the ’50s, at about double the present rate. U.S. women today expect to have 1.9 children over their lifetime. That figure is slightly below the population’s replacement rate, absent immigration.

The CDC said births among teens and women in their 20s also fell to record lows, while births rose among women in their 30s and early 40s. The preterm birthrate declined, but the rate of babies born to unmarried women—about 2 of every 5—was unchanged. —D.J.D.

Submersed giant

Illustration courtesy IODP

The Earth’s largest known volcano is hiding where you can’t see it—underwater. Researchers studying a 400-mile-wide seamount in the Pacific Ocean, once thought to have been formed by several magma vents, say the feature is actually a single, gigantic volcano. Spreading out over 100,000 square miles, the extinct volcano, named Tamu Massif, rivals Nevada in size. It is much larger than the previous volcano record holder, Mauna Loa in Hawaii—although Mauna Loa is taller.

Tamu Massif is part of a plateau called the Shatsky Rise, about 1,000 miles east of Japan. The scientists reported their discovery in Nature Geoscience. —D.J.D.

Daniel James Devine
Daniel James Devine

Daniel is managing editor of WORLD Magazine and lives in Indiana. Follow Daniel on Twitter @DanJamDevine.


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