Readers ask about exoplanet heating sources, combating climate change and COVID-19

cover of May 9, 2020 magazine issue

Warming up

Auroras inject extra energy into Saturn’s a­tmosphere, which may make it hotter than expected, Lisa Grossman reported in “Auroras could heat up Saturn” (SN: 5/9/20 & 5/23/20, p. 12). The same process could take place on exoplanets, scientists say.

Reader Jeremy Schwartz wondered if scientists consider heat sources other than stars when evaluating an exoplanet’s habitability.

A planet can get heat from its star, from the radioactive decay of elements within rocks inside the planet, from gravitational interactions with a moon or maybe even from auroras, Grossman says. Scientists can measure only one of those things for exoplanets: The heat they get from their stars. “From Earth, there’s no way to know how much g­ravitational or radioactive heating an exoplanet gets. It took a spacecraft flyby to figure these things out for Pluto,” Grossman says. “Until we can send a probe to an exoplanet, we won’t know how else it might get its heat.”

Sharing responsibility

Individual actions, including eating a plant-based diet and using renewable energy, can create ripple effects that reduce carbon emissions, Christie Aschwanden reported in “Reducing your emissions” (SN: 5/9/20 & 5/23/20, p. 34).

Reader John Tilson thought the story placed responsibility for combating climate change on individuals instead of on manufacturers. “We as consumers are always made to feel it’s our fault,” Tilson wrote. “I suggest we blame and fix the source of the problem.”

The intention was to show things that consumers can do, not to lay blame at their feet. “There is a shared responsibility and capacity to address climate change for various actors,” says Diana Ivanova, a research fellow at the University of Leeds in England who has studied emissions-reduction options. “Quantifying the carbon footprints of consumption does not mean that consumers are the sole actors with responsibility. Instead, if industry cleaned their activities and governments adopted strong climate policies, this will reduce the carbon footprint of consumers.”


Science News reporters Tina Hesman Saey, Aimee Cunningham, Jonathan Lambert and Erin Garcia de Jesus are f­ollowing the latest research to keep you up to date on the coronavirus pandemic. The team is answering reader questions about COVID-19.

“China recently reported in JAMA Network Open that [the coronavirus] was found in semen,” reader Larry Busack wrote. “Does this indicate that embryos could be created that are infected or that have the virus as part of their DNA or RNA?”

Researchers in China detected the coronavirus’s genetic material in semen, but the team did not determine whether infectious virus was present. There’s no evidence that the virus can infect sperm or eggs, or that semen can transmit the virus to another person.

That said, it’s possible virus bits could become embedded in an embryo’s genetic material if a virus’s RNA or DNA makes it into sperm or an egg. That’s how human DNA has become riddled with remnants of past viral infections. Researchers can use the viral “fossils” to understand how long humans and our ancestors have been infected with certain types of viruses. Not all viruses can infiltrate the DNA of sperm or eggs, however, and the ones that can rarely do. There are no known coronavirus fragments in human DNA.