Immense floating structures could become humanity’s home, harnessing the power of stars. But, Peter Ray Allison writes, building them will be a colossal challenge.
The supermassive black hole is 40 million times as massive as the sun and powers a quasar that existed 700 million years after the Big Bang.
The asteroid zoomed by Earth at a perfectly safe distance of around 1.8 million miles (2.9 kilometers).
Images show surprise changes to the spacecraft as it interacted with the atmosphere.