Asteroid 3122, named after Florence Nightingale, will reach its peak brightness tonight (Thursday August 31 into Friday September 1).
But the asteroid will actually be closest to Earth at 8:05 a.m. ET (1pm BST) tomorrow (Friday September 1), according to NASA.
The asteroid will come as close as 4.4 million miles (7 million km) to Earth but NASA has confirmed that it will not hit our planet.
Paul Chodas, manager of NASA’s Center for Near-Earth Object Studies, said: “Florence is the largest asteroid to pass by our planet this close since the NASA program to detect and track near-Earth asteroids began.”
The asteroid, which is an incredible 2.7 miles (4.4 km) in size, last came this close in 1890. It will not skim so close again until after 2,500.
Astroid Florence will be more difficult to see at the point when it comes closest to Earth because it will be daylight.
Sky & Telescope magazine says the best time to see the asteroid with a telescope will be late this evening when it is high overhead.
Senior editor Kelly Beatty said: "Despite some interference from moonlight, 3122 Florence should be fairly easy to spot in even modest backyard telescopes.”
Alternatively, you can watch a live stream of Asteroid Florence above tonight.
Watch the Virtual Telescope Project live stream from 8.30pm BST (3.30pm EDT) to see the Asteroid Florence 3211 close encounter.
Robotic telescope service Slooh is also showing a live stream of the Asteroid on its website at 2am BST (9pm EDT).
If you miss the asteroid tonight, you have still got a chance of seeing it over coming nights.