The Cosmic Watchdog

Location, location

Scientists launched a rocket from Svalbard, Norway, that measured Earth’s ambipolar electric field for the first time. The weak field may control the shape and evolution of the upper atmosphere and may contribute to Earth’s habitability, astronomy writer Lisa Grossman reported in “At long last, scientists detect Earth’s hidden electric field.”

Reader Jayant Bhalerao, a college physics instructor, found the story useful in class: “We will share it with our students, so that they can appreciate how things they are learning in the textbook have real-life applications.”

Bhalerao also wondered why scientists chose Svalbard as the rocket’s launchpad. “Is there perhaps a scientific reason, or is it just infrastructure?”

To measure the ambipolar electric field, the rocket needed “to measure the escape of Earth’s atmosphere at the poles, where some of the planet’s magnetic field lines are open,” Grossman says.

“Earth’s magnetic field is kind of like a bar magnet, with field lines running from the North Pole to the South Pole in big closed loops. In these loops, charged particles are kept contained to Earth’s vicinity,” Grossman says. But at the poles, some field lines shoot out into space, allowing charged particles to escape. “The only launchpad that’s far enough north to reach that open magnetic region is the one in Svalbard,” she says.

Measuring mergers

Scientists are becoming increasingly optimistic about the possibility of detecting primordial black holes. If they exist, these ancient black holes born just after the Big Bang may shed light on the mysteries of dark matter, freelance writer Elizabeth Quill reported in “Black Hole Dawn.”

Cosmologists hope to spot signs of primordial black holes by studying black hole mergers, especially those with bizarre features, such as unexpected masses and spins.

Reader Michael Cross asked how scientists determine those black hole properties.

Scientists can observe black hole mergers through gravitational waves, which provide all sorts of information about the colliding bodies, says senior physics writer Emily Conover. As black holes spiral inward and merge with each other, scientists can detect “the patterns of waves, how strong the waves are and how frequently they oscillate. They also look at how those patterns compare between multiple detectors,” Conover says. Black holes with different masses or spins “will give different patterns of waves.”

Tip of the hat

Reader Philip Korb shared a note of appreciation for the January issue.

“Your new expanded and glossy magazine is dazzling. Beautiful … and with even more in-depth reporting. The AI in Medicine article was comprehensive, the human navigation article confirmed what using GPS has demonstrated, and the role of guano in creating the American empire fascinating,” Korb wrote. “Science News is an invaluable contributor to American life.”

Korb’s wife, Sandra Wolf, M.D., started reading Science News as a child, back during its newsletter years. Wolf has maintained the subscription for decades, sharing it with Korb when they married.