Only a small handful of objects are known to pose a serious threat to Earth, and the gigantic asteroid Apophis is one of them. Scientists are now re-evaluating its potential to strike our planet in 48 years, owing to improved observations of the problematic asteroid. Observations made earlier this year from the Subaru Telescope in Hawai’i are providing astronomers with a better sense of how the Yarkovsky effect is influencing the orbital path of asteroid 99942 Apophis. This effect is like a built-in propulsion system for asteroids, in which trace amounts of leaking radiation can alter an object’s momentum in...