NASA
A huge space rock named Florence, roughly 4.4 kilometres across, whizzed past Earth at a relatively close 7 million kilometres on 1 September. It is the biggest asteroid to fly near Earth in more than a century.
Astronomers discovered the asteroid in 1981 and named it for Florence Nightingale, the founder of modern nursing. Based on a reconstruction of its historical orbit, astronomers have determined that this fly-by is the closest Florence has come to Earth since 1890. It’s also the biggest asteroid we’ve seen pass this close to Earth since NASA began detecting near-Earth asteroids in 1995.
The rock is highly reflective, as asteroids go, so it was bright enough to be visible in small telescopes for several nights. Astronomers also studied it from Puerto Rico and California using radar imaging. It travelled through the constellations Piscis Austrinus, Capricornus, Aquarius and Delphinus.
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If a rock the size of Florence hit Earth at the speed of the meteor that exploded over Chelyabinsk, Russia, in 2013, it would excavate a crater 55 kilometres across and 1 kilometre deep, and cause catastrophic effects for Earth’s atmosphere and ecosystems.
Luckily, it won’t reach any nearer than 18 times the average distance between Earth and the moon, and it won’t get this close again until after 2500.
Read more: If an asteroid hit London only 3% of deaths would be from impact
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