Readers are curious about dark matter, plastics’ effects on pollination and Percy’s selfies

Let’s talk neutrinos

Two dark matter experiments have spotted signs of neutrinos knocking into atomic nuclei in their detectors. The finding portends a future obstacle for the detectors, Emily Conover reported in “ ‘Fog’ invades dark matter experiments” (SN: 8/24/24, p. 12).

These detectors scan for dark matter’s interactions with the nucleus of a xenon atom. Reader Robert Walty wondered how that could work. Doesn’t dark matter interact with normal matter only through gravity?

So far, scientists have detected dark matter only through its gravitational interactions with normal matter. But the mysterious substance could potentially interact through other forces, Conover says. It is possible dark matter might interact via the weak nuclear force, for example. “That type of interaction is what these detectors are looking for,” she says.

Walty also asked how a neutrino, which is much smaller than a proton, could slam into an entire atomic nucleus.

“Subatomic particles aren’t like billiard balls of different sizes bouncing around. Instead, they act like waves,” Conover says. If a particle’s wavelength is longer than an atom’s nucleus, it will interact with the nucleus as a whole, rather than with an individual proton or neutron. In the case of a neutrino hitting a nucleus, the interaction actually occurs through another particle, called a Z boson, which the neutrino exchanges with the nucleus. If the Z boson’s wavelength is big enough, the whole nucleus will recoil as one.

Pollination and plastics

The electrostatically charged wings of moths and butterflies could draw pollen out of nearby flowers without the insects needing to land on the blooms, Anna Gibbs reported in “Pollination via static electricity” (SN: 8/24/24, p. 13).

Reader Michael Skinner asked whether that static could also attract microplastics and interfere with pollination.

Unfortunately, the answer is probably yes, says ecologist Sam England of the Natural History Museum in Berlin. Microplastics tend to be electrostatically charged, so they would likely be attracted to pollinators with the opposite charge, he says. The materials could also possibly mess with pollination, since they “are known to interfere with many different biological processes in plants,” England says. But this has yet to be tested, so the magnitude of these potential effects are unknown.

Portraits of a rover

NASA’s Perseverance rover has found its first possible hint of ancient life on Mars, Lisa Grossman reported in “Mars rover finds a major surprise” (SN: 8/24/24, p. 6).

Readers asked how the rover, nicknamed Percy, snapped the photo of itself featured in the story.

Percy’s “selfies” are actually a team effort. The rover’s WATSON camera is primarily designed for close-ups of rocks and captures only small parts of a scene. So engineers on Earth direct Percy to take dozens of photos of itself from various angles. Image processing engineers then use software to clean up and assemble the shots into a complete image.