A large asteroid is to pass Earth on Friday, coming within miles of our planet.
Florence - named after Florence Nightingale, the founder of modern nursing - has been tracked by Nasa employees since the 1990s.
It was first discovered in 1981 by an employee from the Siding Spring Observatory in Australia.
The rock measures three miles wide, which makes it the largest asteroid to come close to the planet in recent times.
It is due to fly past Earth at a distance of 4.4 miles later in the week.
Nasa is due to test options for a planetary defence system in the event an asteroid comes onto a collision course with the planet.