February 19, 2025: Where are the missing planets in the universe? Plus, some corals in the Pacific Ocean are fighting back against warming seas, and microbes fill the air we breathe. —Andrea Gawrylewski, Chief Newsletter Editor | | | Artist's illustration of asteroid 2024 YR4. Alejandro Miranda/Alamy Stock Photo | | | • Bird flu update: Three new human cases, millions of dead birds in poultry flocks, and outbreak inspectors fired. | 3 min read | | | Presidential policy impacts on science: | | | imageBROKER.com GmbH & Co. KG/Alamy Stock Photo | | | Corals in the eastern tropical Pacific Ocean have some tactics for adapting to warmer ocean waters, marine biologists have found. Some corals swap out their algal symbiotic partners for more heat-resistant ones. Other corals use rows of tiny hairs on their bodies to "fan" away excess harmful oxygen released by algae that are stressed-out by warm waters. And certain baby corals can modify their own metabolisms to withstand the warming waters. Baby corals are particularly important for conservation efforts because they can travel between reefs to potentially integrate heat-tolerant genes into new locations. Why this matters: In the last two years, sea-surface temperatures have been at record highs around the globe, which has led to disaster for corals. Last year, scientists declared that Earth's corals were undergoing their fourth mass bleaching event on record. "A mass bleaching event is, by definition, a mass mortality event," Terry Hughes, a marine biologist at James Cook University in Australia, told Scientific American in 2024. "The reality is that we are losing literally billions of corals on the world's coral reefs."
What the experts say: If researchers can coax corals to adopt heat-resistant algae or if they activate genes that can deal with heat stress, it raises the corals' chance of surviving future ocean heat waves. "You need to grow corals that are more likely to survive than the corals that died before," says University of Miami marine biologist Ana Palacio. | | | As of February 14, astronomers have observed 5,834 confirmed exoplanets in 4,356 planetary systems. But in this catalogue of alien worlds, there is a noticeable lack of planets of certain sizes and characteristics–namely planets slightly bigger than Earth, around 1.6 to 1.9 Earth radii. Planets the size of Neptune with short orbits around their suns are also strangely absent from the roster.
Possible explanations: When young stars light up, they release extreme UV and x-ray radiation. Planets in close orbit of these suns are bathed in this radiation and their atmospheres burn off, losing mass, in what is called photoevaporation. Another possibility is that, as young planets of a certain size age, they burn off the energy within them that built up as they formed, and with weaker gravity and less insulating gas, they cook away their atmospheres from below as they cool over hundreds of millions of years. Other possibilities: the rapid boil-off of planetary atmospheres during formation, or collisions with other planets.
What the experts say: A tangled combination of these factors may contribute to the dazzling array of exoplanet types. "Our solar system, once thought to be the blueprint for all planetary systems, now stands as just one of countless possibilities—a unique configuration in a cosmos teeming with variety," writes Dakotah Tyler, an astrophysics Ph.D. candidate at the University of California, Los Angeles. | | | Science, Quickly host Rachel Feltman sat down with science writer Carl Zimmer to discuss his new book Air-Borne: The Hidden History of the Life We Breathe. The air around us is "remarkably full of living things," Zimmer says, "And some microbes can travel remarkably long distances." The scientific debate early during the COVID pandemic over whether the virus was transmitted through the air sparked Zimmer's investigation into how much we know about the air around us. Watch the full video, or listen to the podcast, here. | | | • After breaking a bone, the scientific evidence shows that walking around after two weeks helps fractures heal better, writes health columnist Lydia Denworth. Rather than limiting movement, pressure on healing bones aids repair. In the first stages, "a healing tissue called callus forms first, which then turns into bone," she writes. "The right amount of load or movement ... is critical to this process. Too little results in no callus; too much prevents the bone from knitting back together." | 4 min read | | | • A Czech dam project to protect endangered river species was stalled by bureaucracy for years. The beavers in the river built the dam themselves. | The New York Times | • Enter any zip code into this interactive tool to reveal where more than $300 billion of the funds went for infrastructure and renewable energy under the Inflation Reduction Act. | Grist | • An ambitious biotech company bioengineering salmon promised to revitalize an Ohio town. The project fell apart and the town was left holding the bill. | ProPublica | | | A recent sampling found more than one million virus- and bacteria-like particles afloat in outdoor air. Slightly smaller, but still impressive numbers, are found indoors. With every breath, we intake thousands of microbes, and expel just as many on exhalation. Some of these are viruses that can make us sick, but scientists now believe many of the organisms in the air are crucial to our good health. Close your eyes and breathe deeply, my friends. | Thanks for reading Today in Science. Send questions and comments to: newsletters@sciam.com. See you tomorrow. | —Andrea Gawrylewski, Chief Newsletter Editor | | Subscribe to this and all of our newsletters . | | | | Scientific American
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