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Scientists have used human stem cells to mimic the earliest stage yet of embryo growth. Multiple research groups independently report that they grew balls of cells that look like human blastocysts, which form about 4 days after an egg is fertilized by sperm. These experiments offer a window into a crucial time in human development and an opportunity to better understand pregnancy loss and infertility without experimenting on human embryos.
NASA’s InSight spacecraft has revealed the size of Mars’s core by listening to seismic energy ringing through the planet’s interior. InSight’s measurement, taken from the Martian surface, suggests that the radius of the Martian core is 1,810–1,860 kilometres — roughly half of Earth’s. That’s larger than some previous estimates, meaning the core is less dense than had been predicted. The only other rocky planetary bodies for which scientists have measured the core are Earth and the Moon. Adding Mars will allow researchers to compare and contrast how the Solar System’s planets evolved.
Three previously unknown strains of bacteria have been discovered growing on the International Space Station. All are members of the Methylobacteriaceae family, involved in nitrogen fixation and plant growth. Researchers suggest that the three new strains, and a fourth that was from a previously known species, could one day help to cultivate crops in space or on Mars.
Features & opinion
Social-media platforms should reward users for reliable, accurate and trustworthy posts, argues cognitive neuroscientist Tali Sharot. “As a neuroscientist who studies motivation and decision making, I have seen how even trivial rewards strongly influence behaviour,” writes Sharot. She points to Sweden — where drivers were offered prizes for obeying the speed limit, and average speed was reduced by 22% — and outlines how a reward system could overcome the appeal of sharing misinformation.
In 1871, the Ke Au Okoa newspaper documented a major hurricane, including the exact time that flooding occurred and the changing wind directions. It’s one example of how the islands’ Hawaiian-language newspapers, which once numbered more than 100, offer a detailed historical record of extreme weather in the region. Language researcher Puakea Nogelmeier uncovered the data as part of a project to translate more than one million pages of newspaper archives. His team then collaborated with meteorologists to bring the information to light, eventually influencing climate legislation in the state.