NASA scientist’s terrifying warning asteroid ‘we know nothing about’ could wipe out city

She told a major science conference there are around 25,000 such asteroids measuring more than 140m in diameter, but we only know where about 40% of them are. Dr Fast said small objects were “hitting us all the time” and experts are “not so much worried about that”. Asked what keeps her up at night, she said: “It’s really the asteroids that we don’t know about.

Article source: https://www.express.co.uk/news/science/2171695/nasa-scientist-asteroid-space-warning