Asteroid 2019 OK, a space rock that’s been described as being the size of a football field, almost struck the Earth this past month. Why did all of our automated detection telescopes miss it until it nearly hit? Near-Earth asteroids like 2019 OK move fast, so telescopes look for dots of light that change position quickly from image to image. But you can’t spot an asteroid that way when it’s coming straight at you.

At the joint meeting of European and American planetary scientists held in Geneva last month, I felt bombarded by a blizzard of new data and ideas coming at me. The small asteroids being explored by Japanese and American spacecraft are tossing off debris in a completely unexpected way, adding to the challenge of manoeuvring towards their surfaces to collect a sample. A comet is approaching the Sun on a hyperbolic orbit, moving so fast that it clearly is not a part of our solar system – the second such object to be seen in two years. An Earth-like planet has been found in the “habitable zone” of another star.